Porsche 914 EV Conversion

Update to Azure Dynamics DMOC Information

2009-12-20T11:26:00.000-08:00

I've been receiving several requests this past year for the FTP site that contains the information on the Azure Dynamic DMOC445 controller.

I just received word from Azure Dynamics that they posted all this relevant information online here:

http://www.azuredynamics.com/products/force-
drive/TractionMotorswithDigitalMotorControllers.htm

Have a great Holiday Season!

Cheers,
Tim

Saying Goodbye to my 2007 Dream Project

2009-02-08T15:41:00.001-08:00

I contacted someone who expressed interest in purchasing the 914 a few months ago and that contact came through for me.

Here's my parting shot with Dan, the new 914 EV owner. Dan has worked with a Bradley GT EV before, so he knows the ropes. I'm sad to see the car go, but I've got the Civic-EV and it does very well. I'm still active on the 914ev Google Group answering questions, so I'm not completely disconnected.

Farewell 914EV... I learned more than I ever expected.

Best wishes to all doing EV conversions.

Cheers,
Tim

Time to sell the 914

2009-02-03T22:01:00.000-08:00

It's time to sell the electric 914. It's been a fun road, but I have three cars now (as a single guy) and only a 1-car garage in the middle of the city. The car has been good to me and made the electric Civic project go so much faster. I've learned much and shared many experiences with other people converting 914s. The car has been a major hit at EV shows and with friends.

Having just finished the Civic-EV, I realize that I need a car that seats more than just two and holds more than just a small bag in the trunk.

You can see more information on the car at the EVAlbum entry:

http://www.evalbum.com/1137

Please contact me at the e-mail listed at the link above in case you're interested.

Many best wishes to everyone,
Tim

Bypassing theCharger

2009-02-03T18:41:00.000-08:00

Since my battery voltage never gets above the cutoff point for the Zivan charger bulk phase, I made a special charging cord with a timer built into it. If I leave the Zivan in low-current mode, I only pull 12 amps, which is less than the 15 amp rating of the timer.

Since I know how many amp-hours I pull from the batteries during my commute, I can generally pick a good timer setting to get the batteries close to full without "boiling" them too much. I think this will work out fine until I replace the batteries or sell the car.

Not ironically, I've been having problems with the charger on the Civic-EV not getting out of bulk-charge mode too, so I built a second timer-cord for that car too.

Battery Degradation

2008-12-31T07:52:00.000-08:00

Ugh. I think my battery pack is slowly dying after 8600 miles and 1.5 years.

My Zivan charger alarm has gone off for the past week and I finally looked into it. Apparently the alarm is indicating a timeout that the charge cycle is taking too long for the capacity of batteries that I have. If I charge overnight, I wake up in 40 degree weather and the pack is very warm, around 80 degrees with vigorous "boiling."

After doing some analysis yesterday, it looks like the batteries are not getting past the initial "bulk" charging phase. The charge curve in my Zivan dumps maximum current onto the batteries until the voltage reaches 171.6 volts and then holds it there until the current dies down before putting a final equalizing charge on it. I found that the whole pack during bulk charge never gets above 170 volts, even after several hours of charging. It seems like the plates are sulfated enough to reduce their capacity and reduce the "gassing" voltage significantly.

After contacting Zivan tech support, they said that lead-acid batteries typically get 400 deep cycles or 800 half-cycles at best. If my average trip is 20 miles between charges and I have 8600 miles on the car, that means about 430 half-cycles. This seems a bit low to me, but since this is my first EV, perhaps I treated the batteries poorly the first time around.

With the significant gassing happening, the front luggage compartment also has some acid rust under the front box (similiar to the "hell hole" in the original 914 engine compartment). I'm a bit disappointed, but it's been a good run.

On a side note, I also blew a fuse yesterday after cleaning out the rear trunk because I pushed two of the fast-on connectors together under one of the tail light assemblies. If your fast-on connectors under the tail lights don't have heat-shrink tubing around them to prevent shorts, I hightly recommend that you add it. It only takes 15 minutes and will save a lot of headaches.

Happy New Year

Fixing the Aux Battery Killer

2008-10-17T19:10:00.000-07:00

I took the time today to research the 914 wiring diagrams and find the annoying connection that leaves my tail light on after I turn off the ignition switch.

If you remove the front dashboard cover and look under the steering column, you should see two connectors. Remove the right one as shown above.

On the rear of the connector should be three wires colored grey, grey/red and grey/black. Snip the grey one and seal BOTH ends with heat-shrink tubing or end-wire crimp. After cutting this wire, you will no longer have the feature that turns on your tail lights when you leave the turn signal lever activated. It's important to protect both ends because one is tied directly to the 12V battery through a fuse and the other gets 12V when you turn the tail lights on. You don't want either of these touching any part of the grounded chassis.

I really hope I'll never kill my 12V battery again by leaving on the turn signal. Other critical functions (like the emergency flashers) still work fine.

Okay, back to driving and finishing up the open-source Civic project. Best wishes to all.

Quirky Porsche Features Killed my 12V Battery

2008-10-14T19:22:00.000-07:00

The Porsche 914 has a bunch of "distinctive" features that make it different from many other cars. One is the hand-brake being on the left side of the driver's seat (enabling a "racing start"). Another quirk is that if you leave the turn signal on after removing the ignition key, your tail light on that side stays on. This has the unfortunate side effect of draining your 12V battery.

I've left my turn signal on before, but the combination of the LED tail-lights and the deep-cycle accessory battery kept the car alive. Well, today my 12V battery died. I was able to "jump-start" the car by using my 12V fan-power transformer to activate the DC-DC converter relay. This enabled the DLS-45 DC-DC converter to quickly charge the 12V battery off the main pack. Unfortunately, the 12V battery had drooped down to 3.2 volts which is a very bad sign.

I ran out this evening and purchased a 12V AGM battery to replace it. The non-spill properties of this new battery will also prevent acid splash from hurting the front of the trunk.

For the future, I'm going to find that dang wire (it's in the electrical diagram) that enables the "leave light on when turn signal activated" feature and cut it. I'm also thinking about drilling a
small hole in the side of the DC-DC converter relay so I can easily "jump-start" my 12V battery by simply inserting a non-conductive pin to force the relay arm closed.

The adventures just keep coming. Best wishes to all in the process of their EV conversions.

Cheers,
Tim

Just passed 6000 miles and fixed PakTrakr Issues

2008-09-14T13:07:00.000-07:00

Two quick updates for the 914 EV since I've started working on the Civic-EV:

First, I just passed 6000 EV miles and the car is still going strong.

Second, the PakTrakr system has been acting up and reporting battery failures. At first, this really worried me that my battery pack wasn't doing well. Many first-time EV builders burn out their pack early.

Upon further inspection, the PakTrakr was reporting failures on batteries that were adjacent to the fusible links in the rear battery box and the front battery box. I tried an experiment by moving the PakTrakr battery wire from one side of the fusible link to the other. This should have theoretically caused no change because the fusible link should have no resistance. I was a bit amused to find that the "failing" battery jumped to the battery attached to the opposite side of the fusible link.

This experiment tells me that the fusible link has enough resistance to confuse the PakTrakr into thinking that a battery is failing. It shouldn't be too surprising since 200 amps going through 10 milli-ohms will cause 2 volts of drop, indicating a bad battery. The bolts on the fusible link metal had loosened up a bit and I suspect they had corroded as well, since the "fuse" is a different metal than the copper bar. I added Noalox anti-corrosion compound to the ends of the "fuse" metal and tightened down the fuse bolts to hopefully fix the problem.

Until something else major comes up, most of my efforts will be over at the Civic-EV blog.

Cheers, Tim

Switching Gears and Moving On

2008-04-07T20:37:00.000-07:00

With almost 3000 miles of cheap, reliable operation, I think it's time to move on to something that will help more people do their own conversions. I really appreciated the high-quality parts and detailed instructions provided by Electro Automotive with their 914 kit. I would like to see the same thing done for a more modern, practical vehicle for much less cost.

You probably won't see much more activity on this blog in the upcoming months as I focus on developing an open-source EV kit for a '92-'95 Honda Civic. I invite you to come along for the ride over at civic-ev.blogspot.com

Thanks to everyone who has offered their support and knowledge during the 914 conversion. I hope this blog has helped many people convert their own 914s and save them time.

Cheers,
Tim

Going back to CAMP914

2008-04-05T11:39:00.001-07:00

Yesterday was fun. I drove the electric 914 back out to Camp914 where I originally purchased the car and drove it away as a gasoline vehicle. Craig was happy to see me and took several pictures. Since the round-trip drive was 44 miles and included several long hills, I charged up for an hour out at camp just to give myself a bit of breathing room. Overall, the car handled the freeway and hills well.

Here's the 914EV charging up at Camp914.

Camp 914 is a fun place with many 914s as well as other Porsches and classic cars.

On a slightly more frustrating note, the LED flasher still isn't behaving the way I like it to, so I took it apart again to see if I could adjust the resistor values. I tested the unit by hooking it up to a 12V SLA battery and applying varying resistances to the output terminal to simulate different light-bulb loads. In my haste, I tried to unsolder a resistor while the battery was still attached and I fried the circuitry (oops!). I guess experience varies proportionately with equipment ruined. I ordered another flasher and put the original one back in the car along with two incandescent bulbs to give it enough load to operate.

I've mentioned before that I'm working on an open-source EV kit. Today I drove out to the U-Pull-It wrecking center and took a bunch of pictures of '92-'95 Honda Civics to see how I could design battery racks for them. The 914ev blog might be winding down as I put more time and energy into the open-source project with its own blog. I'll keep y'all posted as this gets going.

Cheers,
Tim

Going to the Portland Better Living Show

2008-03-29T07:35:00.000-07:00

Yesterday was a long day. I spent over seven hours on my feet at the Portland Better Living Show displaying the 914. My throat was hoarse at the end of the day from answering the same questions many times. Overall, people were very interested and I'm hoping a few will show up at the next OEVA meeting.

Many thanks to Gary Graunke (who set this whole thing up), Ken (forgot his last name) and Joe Williams (on the left) for hanging out with me during the nine hour show. Joe and Ken will take care of the booth today and I'll finish up the last six hours tomorrow.

On a side note, I purchased a DVD from Bob Bath regarding his CivicWithACord project. He's documented much of the work needed to get a fifth generation ('92-'95) Civic converted to electric. This is one of the prime candidates for the open-source vehicle conversion kit I'd like to work on, so there's lots of information to leverage.

Installing LED Lights and Fixing the LED Flasher

2008-03-21T12:34:00.000-07:00

I received a shipment of 3-watt LED lamps and a low-load flasher relay from superbrightleds.com yesterday. The bulb bases were the same, so replacing the bulbs was easy. I ordered the CF13GL-02 LED flasher relay, which is a plug-in replacement for the Porsche 914 relay and responds to the much lower current pulled by the LED lamps.

After installing everything, I found out that the LED flasher was able to detect such a low bulb current, that it was stuck in the "on" mode (relay clicking) all the time. I measured 3 MegaOhms between the bulb output terminal and ground, even with all the lights turned off. I'm guessing this probably comes from leakage through grease or other leaky paths in the system.

Soooooo, I guess it's time to reverse-engineer yet another component that doesn't work...

Here's my dining room table with the test setup. I drew out the schematic of the LED flasher and got the datasheet for the PNP transistor that was activating the circuit.

Here's the modified flasher relay. Without going into too many details, I replaced one resistor and shunted one terminal to 12V with another resistor so that the input ignores loads with a higher resistance than about 200K ohms.

I'm a bit discouraged that people are selling this relay knowing it doesn't shut off in a real automotive environment.

Addendum: Here is the partial schematic for the LED flasher with suggested hack to fix the flashing problem with a leaky terminal.

Ah well, I'm happy with the results, and the flashing LEDs look great.

Cheers,
Tim

2000 miles and counting

2008-03-06T19:47:00.000-08:00

I broke 2000 miles with the 914 EV this week. The car has been running smoothly with no complaints. One of the "features" of the 914 is that the turn signals come on (but don't flash) if you leave the turn lever in the "left" or "right" position, even when the ignition is turned off. This presents the dilemma of running down the 12V battery while the main pack is charging. If the 12V battery is dead, you need a small 12V battery (9V would probably work) to activate the DC-DC converter relay to bootstrap the 12V charging process.

The PakTrakr with the series 100 ohm noise-reduction resistor has eliminated all the spurious error alerts. I took a serial log of all the batteries during my commute (graph below) and found battery #11 (the second battery in the front compartment) to be drooping slightly more than the others. I noticed that it tended to have more acid around the battery caps on top of the battery and it's fluid level was lower. The accuracy of the PakTrakr is only 0.1V so the voltage droops look like sharp steps on the graph.

UPDATE: Roger asked me to explain the graph above in a little more detail. The PakTrakr logs voltage for each battery and then dumps it out a serial port in .csv (comma separated) format for MS Excel. I captured the above graph from the chart that MS Excel generated. The batteries are 8 volts apiece and the serial port dumps tenths of a volt (scale on the left edge). This graph displays voltage for all 18 batteries (each is a "series) in the system. As I drove to work with acceleration and regeneration, the voltage on the batteries varied. The batteries with reduced health or capacity will tend to droop lower during heavy acceleration and spike higher during regenerative braking due to higher internal resistance or lower energy capacity. As I mentioned earlier, I found that series #11 on the chart was consistently at the lowest value during heavy acceleration periods, so I suspect that battery will have some issues sooner than the others. I topped off its water to increase its storage capacity a bit. You'll also notice that the "steady-state" voltage at the end of the chart is lower than at the beginning, showing that the pack has gone through some discharge during the 15-mile commute.

I'm getting more involved with the OEVA club. If I don't get elected co-chair next Thursday, I'm going to start an open-source EV conversion kit sub-group within the OEVA. I even have a lawyer friend who is willing to assist with some of the open-source gotchas involved in such a project. Researching my motivations and how much I'm willing to throw myself into this will definitely be important.

Have a great weekend everyone.

Fixing PakTrakr Signal Integrity

2008-03-01T21:05:00.001-08:00

Well, I played around tonight and looked at some of the PakTrakr signals on the oscilloscope and found some noise on the data line going between the PakTrakr "remote" modules. It looks like each PakTrakr remote has three wires coming out of them:

Black - zero volts from that module
Red - 11-12 volts from that module
Green - 3.3 volt signal that sends a pulse train every second (pulses to zero volts)

The signal on the green wire had significant over and undershoot on it, so I thought of ways to take the edge off the signal.

Here's my experimental setup. I added series 100-ohm resistor to the green wire going into the PakTrakr module and all the noise cleared up. The messy serial output from the display module cleaned up too. In the picture above, the wire from the rear PakTrakr remote is the gray wire coming up from the lower right corner. I have some alligator clips and an o-scope probe tied into the mess and insulated with masking tape (what hack job). The alligator clips allow me to insert various series resistors with the green wire. Again, 100 ohms seemed to do the trick nicely.

I gave feedback to Ken Hall at PakTrakr.com so hopefully he can incorporate this into his future designs. The only other thing that bugs me about the PakTrakr is that the modules seem to be made of teflon. No tape I've tried will stick to the back of them. I'll probably end up attaching Velcro with epoxy or something.

One more problem (hopefully) solved...

Playing with PakTrakr

2008-03-01T19:05:00.001-08:00

Many months ago, I installed a PakTrakr (www.paktrakr.com) to monitor the state of my batteries and it's been acting rather flakey. The PakTrakr consists of several serially connect "remotes" which drive a "display" unit in the driver compartment. The voltage displayed shows the pack voltage and is supposed to monitor the state of each battery and the State-Of-Charge (SOC) for the pack too.

In short, the voltage displayed jumps around quite a bit. The different in voltage jumps correlates closely with the voltage being monitored by an individual "remote" unit, so I'm guessing that the communication link is bad. I contacted Ken Hall at PakTrakr.com and he suggested adding EMI suppression cores to the links between the "remote" units to cut down on electrical noise. So, I collected a bunch of spare EMI cores from a local computer recycling center and wrapped the remote cables around them. I also put dielectric grease on the connections to see if that would help with corrosion and connectivity. The result: The noise problems got far worse and the PakTrakr display doesn't register anything meaningful.

It's possible the dielectric grease messed up the connections, so I'll try removing the EMI cores and see if I still have the problem. This is not a critical part of the car, but it would be nice to measure the state of the batteries. It turns out that the Zivan charger is doing a reasonable job of over-charging the flooded batteries to keep them balanced. I've only had 50 millivolts of difference between the highest and lowest voltages when I get home from work after 16 miles of driving, so I think the pack is still doing okay. I hope this pack lasts 2-3 years while the costs of lithium batteries come down.

On a slightly non-914ev related note, I'm going to be running for a co-chair position within the Oregon Electric Vehicle Association. If I don't get elected, I'd like to start an open-source EV kit that uses all local businesses to manufacture the custom car parts with freely available designs. We'll see what this year has in store...

Cheers,
Tim

Charging Up on Roadtrips

2008-02-24T13:17:00.000-08:00

I'm considering taking the car on some slightly longer journeys this summer and don't want to be caught out in the middle of nowhere with a dead battery, so I ran out and purchased a Honda generator that can charge the car for four hours to get a few more miles out of it, if necessary.

I tried firing up the generator with a little gas and it didn't go into overload with the Zivan charger at the 60% (12 amp) setting. The generator puts out 1600 VA (technically 13.3 amps), but the charger has a power factor of 90, so 12amps/.9 is actually 13.3, which puts the generator at its rated capacity. I figure four hours of charging starting with the battery at 80% DOD will be acceptable for another 20-30 miles. I might also be able to pull off the freeway and find a plug-in at a gas station, but this would work anywhere.

New Brakes and Local Lithium Supplier

2008-02-23T16:41:00.000-08:00

I took the 914 back to A&P Specialties yesterday to upgrade the front brake calipers with ones from a BMW320i. The brake pedal definitely feels different. I can push it a lot farther towards the floor and the pads seem to bite quite a bit more. I hope this will help with any emergency braking I might have to do.

Given the sluggish acceleration of the vehicle, I started looking into lighter batteries. Apparently, I can purchase Lithium-Iron-Phosphate (LiFePo) packs from Electric Wheels in Salem, just an hour south of here for the whopping low price of $12,500 for a 100Ah/144V pack. It would take about a 1000 pounds of the weight of the car and the pack would last many times the life of the lead acid batteries. I think I'm going to let the existing pack go out and reconsider these new batteries in a year or two. Things might get really interesting with so many new electric vehicles coming out.

Magazine Article and 914 EV Wiki

2008-02-12T19:47:00.001-08:00

I ran out to Barnes and Noble today and picked up the March issue of Sports Car Market magazine. My 914 was featured on page 38 along with John Benson's 914 DC conversion! I hope Electro Auto doesn't get even more swamped by the publicity. I'm glad these EVs are getting coverage so more people can see what's possible.

For those of you who have converted your own 914 to electric, I encourage you to contribute to the Electric Conversion page of the 914 Wiki at RoadGlue.com:

http://www.roadglue.com/wiki/index.php/Electric_Conversions

I spent most of last Saturday culling data from the 914 EV blog sites and writing the Wiki page so that others could get their questions answered and get technical assistance when they ran into problems.

I've commuted to work the past two days and the "smoothing out" modifications I mentioned a few posts ago work really well. With the transmission fixed, the DC/DC fixed and the DMOC445 smoothed out, I'm starting to relax and really enjoy the car. (Got that EV Grin again...)

Federal tax law doesn't let me get a rebate from the feds because the car isn't a fully qualified conversion; however, I applied to the State of Oregon to get the state rebate of $750. It's better than nothing. The federal rebate on qualified vehicles (all hybrids at this point) is up around $2000, I think. Maybe for 2008, at least the Tesla roadster will get on the list. Their first production car (not a prototype) just came out a few days ago.

Reflections on Converting a 914 to an EV

2008-02-09T16:13:00.000-08:00

Many things have passed through my mind over the past year and a half while converting this vehicle. I'd like to capture some of the good and bad things to help keep other people from falling into the same holes as I did. Here goes (in no particular order):

Things That Went Well During the Conversion

The 914 AC kit from Electro Automotive is a good one. The parts are high quality and the instructions take the user through the process step by step.
I received much support and encouragement from everyone around me. This included the folks at the Oregon Electric Vehicles Association, the motor control engineers at my work (HP), the communities at 914world.com, the other 914 EV conversion folks (Thanks to Randy, Ross, Roger, Matt, Paul, and many more...) If you do your own conversion, tap into all these resources whenever you have an issue. Most people are very happy to help.
I had all the suspension, alignment and brake work done at a local shop called A & P Specialties run by Alan, who was also very supportive.
The conversion car came from camp914.com and had very little rust and good structural integrity. Craig at Camp914 was also very supportive and let me swap parts when I needed something small to get the non-EV portions of the 914 working.
I modified the wiring in the original 914 AC kit (as suggested by Paul Jorg) to turn on the regen when the brake lights came on instead of controlling regen by releasing the accelerator pedal. This made the car much easier to drive (similar to an ICE vehicle). Azure Dynamics is going to add this rewiring to their future DMOC controller wiring diagram to help other EV conversions.
Given the huge support from the OEVA community, I was able to borrow a "real" crimper to attach all the lugs to the 2/0 gauge welding cable. This made the job much easier and I feel the crimps are much better connections.
I had a switch added to the Zivan NG3 charger which turns it down to 60% power, allowing me to plug into any 15 amp 115VAC socket at work and at friends' houses. I highly recommend sending your Zivan charger to the US support folks for this modification. It only cost me $60.
Adding a "real" battery monitoring system like the PakTrakr was key in monitoring the state of all the batteries. Support for the PakTrakr was excellent despite some of the noise in the system which caused spurious readings. One might consider using the EVision system from MetricMind too.
Writing a blog using blogspot.com was great for many reasons. First, I was able to keep track of my progress. Second, other folks could learn from what I had gone through. I often refer people back to specific pages when they have questions about their own conversions. Third, it greatly increased visibility to the online community and I'm hoping it raised awareness of EV conversion issues. The feedback I received from people was excellent. I even received a few posts from Mike Brown at Electro Automotive, the designer of the kit.
I really enjoyed working with Beth Silverman at Azure Dynamics. The AC24 motor and DMOC445 controller system are highly configurable. The AC motor also provides regenerative braking for free, which also aids in stopping the car with the heavier battery weight. It was easy to capture logs of system behavior, e-mail them to Azure Dynamics and get a good technical response back in a day or two. Beth and the Azure engineers saved me countless hours of debugging time by analyzing these logs and pinpointing problems with my setup.

Things That Didn't Go Well During the Conversion

I was rather disheartened by the uncertain delivery times of kit parts from Electro Automotive. The critical parts needed to complete the car took eight months for delivery. It's not the eight months that bothered me, but the claim by ElectroAuto that it would only take two months and then not communicating the delay to me. I still haven't received several of the non-critical parts such as gauges, hydrometer and some other things. If you order a kit from Electro Auto, make sure you have patience in waiting.
Most of my support for this kit came from other members of the EV community. This was rather disconcerting considering that my kit was the first 914 AC kit to ever be completed. I received minimal support from ElectroAuto and received most of my documentation from other 914 AC kit members who passed it to me "on the sly." I've heard of at least two other people who received their kit parts but no 914 AC instructions. They ended up asking me for the directions after receiving no response from ElectroAuto.
I'm not entirely sure why, but ElectroAuto shipped #2 gauge cable with the AC kit instead of the standard 2/0 gauge cable that came with the earlier 914 DC kit. The AC kit still pulls 300 amps and benefits greatly from the much thicker cable. If you get #2 gauge cable, go to your local welding shop and replace it with 2/0 gauge. The small expense of $150 will extend your range and power greatly. You can even cut a few strands off the edges of the stripped cable and jam on the #2 gauge lugs to save cost.
The transmission on the original 914 was bad and rattled the car violently. In my enthusiasm (read hubris), I tried to rebuild it myself. This is a job requiring special tools and expertise. If I had to do it again, I would definitely send it out for rebuilding by someone else or just purchase a newly refurbished 914 transmission. The old one sold nicely. The folks at 914world.com have a member named "Dr. Evil" who does rebuilds for a very reasonable price. I bought a refurbished one for $850 shipped and sold the old one for $250.
I should have joined an online community of 914 owners at the beginning. There were several issues with the original car that I could have saved loads of time on (especially the transmission) by asking other (non-EV) 914 experts. It also provides an excellent place to buy and sell needed parts far more cheaply than other online sources. The online support for the 914 is very good, especially the technical articles at Pelican Parts.
The AC24 motor from Azure Dynamics is significantly underpowered for the 914 AC kit. It's acceleration at zero RPM was less than half the original ICE engine and half of that (at zero RPM) of the Advanced DC 9" motor in the 914 DC kit. If I had to do things over, I might seriously use the DC kit. The first question everyone asks me about the 914 EV is "how fast is it?" Most people seem to want want greater range, but are not willing to give up starting torque for it, especially for a Porsche. Azure Dynamics is trying to address this with the newer AC24LS motor which has 15% more power, but I don't know if that'll be enough. In short, paying $4000 more for the AC kit and getting half the power was frustrating.
The CCPower C400 DC/DC converter kept dying on me. There was virtually no support from the supplier and I ended up reverse engineering the whole unit (since a new one was $400) and worked with the power-supply engineers at my job to fix it. The unit still failed to work properly and I ended up replacing it with an Iota DLS-45 unit which sells for $135 and is commonly sold at the EVParts.com site for electric conversions. It also fits in the same space as the CCPower unit and puts out 50% more amps with no noise (the CCPower unit squealed and buzzed). The customer service at Iota Engineering was very prompt and answered all my questions quickly. Having said that, another 914 AC customer has reported zero problems with his CCPower unit, so I might have just had a bad unit.

General Themes During the Conversion Process

Converting a 914 to electric is a group effort. As mentioned above, I received support from the 914 community, the EV community, my co-workers, and many friends. People feel connected when they can contribute to another person's success and I found no end to help for this project. Get connected with the online 914 community at 914world or 914club.com as well as with your local EV community.
Converting a 914 to electric is a process. There will be many unexpected problems, especially with a 30+ year old car. The AC kit had never been completed before and the instructions were a bit sketchy. I had to remind myself several times that I'm doing this for enjoyment and to take many breaks to keep from getting frustrated.
Converting a 914 to electric is a hobby. The phrase "There's a fine line between a hobby and insanity" comes to mind. This hobby will cost you far more than any amount of money you will save in gasoline when driving it around. The cost of the kit is roughly equivalent to eight years of gasoline. If you want a fuel efficient or no-gasoline vehicle, it'll probably be cheaper to buy one already made. There are also many avenues (Porsche clubs and EV clubs) that let you enjoy things vicariously without having to blow $20,000 on your own kit.
Understand your motivations and your motors. I purchased the kit as a no-gasoline commuter car solution. Most people want their Porsches to go fast, not long distance. The DC kit is better for a fast car, the AC kit better for smoother driving and (possibly) longer range, although that has yet to be proven.

As stated from day 1 in the title of this blog, all this information is meant to help others in considering their own conversions and getting through the process. Despite having made several "less than shining" comments about Electro Automotive, they are still a great company and nobody else makes a quality product like they do. I perceive them to be simply overloaded given the enthusiasm surrounding electric vehicles these days.

I wish everyone well in their path towards EV-dom.

Smoothing out the DMOC acceleration/braking

2008-02-09T15:47:00.001-08:00

One of the annoying behaviors of the motor system in my AC 914 kit is that the default DMOC445 parameters causes the acceleration and braking to have oscillations. In physics speak, the application of the positive or negative torque happens so quickly that the system is underdamped. The step function of the torque perturbs the mass of the car and it oscillates for a bit before settling down, primarily in first gear where the motor has the most influence on the acceleration and deceleration of the car. These oscillations can put extra stress on the drivetrain and cause general annoyances with the passengers.

So, I took the car out into the neighborhood with the laptop hooked up and started playing around with the EEX???TorqueSlew parameters listed in the DMOC445. The original parameters are:

EEXTorqueSlew: 985 Nm/s
EEXUnloadTorqueSlew: 985 Nm/s
EEXBrakeTorqueSlew: 477 Nm/s

When I floor the accelerator in first gear, the car oscillates (EEXTorqueSlew) and then oscillates again when I quickly release the accelerator (EEXUnloadTorqueSlew). Similarly, when I apply the regen brakes in first gear, the car lurches forward and oscillates (EEXBrakeTorqueSlew). When I release the regen brakes, the car oscillates as well(EEXUnloadTorqueSlew again).

After some messing around, I finally settled on the following values:

EEXTorqueSlew: 209 Nm/s
EEXUnloadTorqueSlew: 388 Nm/s
EEXBrakeTorqueSlew: 239 Nm/s

These new values slow down the rate that torque is applied or removed in the system. With the new values, I can accelerate and regen-brake in first gear without any oscillations but still get relatively quick response from the pedals. In fact, the reduced EEXBrakeTorqueSlew allows me to up the MaxBrakeTorque variable to 60 Nm/s for better braking without having the passengers lurch forward. This is very important due to the weakness of the 914 manual brakes combined with the additional 800 pounds of battery weight.

At this point, the last major thing to fix on the car is upgrading the front brake calipers to BMW320i parts to improve braking. Beyond that, I'm just trying to get out as many thoughts as I can before just commuting with the vehicle and enjoying it.

I've started an 914 Electric Conversion Wiki at the URL below. Please contribute to the Wiki as you can. The Wiki is a shared resource as opposed to an individual blog, so I'm hoping we can save people time by putting our collective brains together and helping people move forward in converting their 914s to electric. I'm hoping this will also save us all some time in that we don't have to answer the same questions over and over to new people considering 914 conversions.

http://www.roadglue.com/wiki/index.php/Electric_Conversions

Thanks to everyone for their support on this project.

Cheers,
Tim

New Tranny Fluid, Battery Filler and EV Toolbox

2008-02-08T13:14:00.000-08:00

I tied up a bunch of loose ends today on the 914EV. I replaced the transmission fluid with the synthetic Royal Purple fluid from ElectroAuto. The transmission seems to spin more quickly and run quieter, but that is a highly subjective assessment. I'll know more by the end of next week.

I tried using an automatic battery filler from NAPA to fill the batteries, but the nozzle kept jamming and the weight of the water in the tank wore out my arm muscles. To help with the situation, I ran out to Fred Meyer and purchased a one-gallon pressurized garden sprayer. If I adjust the nozzle correctly, it sprays water into each battery cell chamber without splashing and also disturbs the surface of the acid so I can more clearly see the acid level. Since the weight of the water is resting in the main tank, I can more easily fill up the 72 cells (4 cells x 18 batteries) without my arm getting tired.

I also purchased a plastic toolbox for the trunk filled with most of the stuff I listed in this prior blog entry, just in case I had problems out on the road. This box wedges nicely between the DMOC445 controller and the right wall of the trunk so it doesn't move around.

I found quite a bit of water in the rear trunk during these rainy days, so I added the weather-stripping that I had never installed from the original ElectroAuto kit. This picture shows the weather stripping on the bottom edge of the trunk lid just above the silver PORSCHE letters.

The last project for the day is adding loc-tite to the bolts on the steering wheel. They keep coming loose with road vibration and I'd rather not end up with a steering wheel in my hands without the ability to steer.

Cheers,
Tim

DC-DC Installed and New Brake Parts

2008-02-07T22:15:00.000-08:00

In was eager to get the new DC-DC converter installed so I left work a bit early and got to work so I could still drive the car to breakfast with my girlfriend tomorrow morning.

Here's the mostly final installation. The wiring is a bit messy because I had to cut all the tie-wraps off from the original setup. I just wanted to try this out for awhile before taking the time to clean it up. The DC-DC converter fits rather nicely in the old space.

Here's a closer view of the top of the Iota DLS-45 converter. This is the slightly older model (I guess the shop was clearing them out). The newer version is the M series and is even smaller and has no heatsink fins on the sides. This version had mounting tabs that fit well with the bolt holes from the original kit. The right tab hole lines up with the bolt in the upper right corner of the battery box. The left tab hole was very near the upper left bolt that held the old DC-DC on, so I just drilled a hole and used the original screw. I didn't want to hassle with the bottom two tabs, so I lined the whole back of the converter with Velcro and it isn't budging!

Okay, the first test drive with the new converter was very successful. I turned on all the lights, including the fog lights and drove around for about 20 minutes. The 12V voltmeter in the center console never dropped below 12 and stayed at 13 volts most of the time, even with the headlights on. The new converter is dead silent. There is no squealing or buzzing like the old one. One additional advantage is that the input is really a rectified 115V AC input that I can plug into the wall in case I need to recharge the 12V battery with an external source instead of the main pack. So far, I'm very happy and will report back in a week or so if there are any problems.

The next big problem I'm working on is improving the brakes. With the added weight of the batteries, the vehicle is very difficult to stop, especially on downhills at stoplights. One common way of improving the braking on the 914 is to upgrade to BMW 320i front brake calipers. The later model 914s ('73 and later) need to have the 320i calipers machined for proper spacing.

I purchased the pre-machined calipers above from the classified section over at 914world.com. I highly recommend joining 914world.com or 914club.com to ask all non-EV questions about the 914. People have been very helpful and supportive in figuring out all those quirky bugs in a 35 year old car. One of the more difficult parts to find were the steel brake lines. These lines are from Schucks Auto Supply part number PAE312. They need a "European" bubble flair end to fit the calipers. Most auto parts stores carry these; however, the difficulty was in picking the correct ones since most places are not familiar with the 914 brake upgrade. I'll probably call Alan at A&P to get these installed in two weeks or so when I have a free Friday.

Good Night.

New DC-DC here and Tranny Fluid Too

2008-02-06T21:26:00.001-08:00

I let out a major sigh of relief today when the new Iota DC-DC converter showed up today along with the synthetic transmission fluid that ElectroAuto said they would send me. I'll start the installation tomorrow after finishing my third week of commuting to work. I've been biting my nails over the past few weeks, living in fear that my 12V battery would suddenly run out on the freeway in the rain as I drove with my headlights on.

Here's the Iota DLS-45 12V power supply. EVParts.com sells it as a DC-DC converter for many of their electric vehicle conversion kits. It cost me $130+shipping and is spec'ed to put out 45 amps, which should be very adequate for running all the 12V accessories in the car. It's a bit larger than the CCPower C400 DC-DC converter supplied with the kit, but it still fits in the same space and can be plugged into a 115V AC outlet for charging the accessory battery offline. EV conversion kits have you make a three-prong plug with the hot and neutral tied to the main battery pack to supply this converter.

I just got an e-mail from Randy today describing how he saved a bunch of current by replacing all his bulbs with LED ones. The LED bulbs require a modification to the flasher circuit due the greatly reduced load. I'll post that when I get the details from Randy.

I also received three quarts of Royal Purple synthetic gear oil from ElectroAuto. The stuff I have in the transmission seems to work fine, but I suspect this will provide less resistance to the electric motor. With the lack of torque, I'll try several things to improve the performance.

A few days ago, I also received an e-mail from Beth Silverman at Azure Dynamics. She mentioned that there is a slightly longer version of the AC24 (called the AC24LS) that puts out 15% more torque and is only an inch longer. If you get the 914 AC kit, you might seriously consider getting this upgrade, although I don't know the additional price. My gut tells me that if the AC motor ever dies, I might just replace it with a 9" DC motor to get a bit more power since distance isn't as critical to me, although the regenerative braking is nice. Just the cost of the DMOC445 controller is the same as a 9" DC motor, motor adapter and Curtis controller.

Opinions and Rants

2008-01-28T20:05:00.000-08:00

I lost much sleep last night obsessing about how I could fix the DC-DC converter and, as a result, I was very tired and had an irritable day. For those of you who have read my blog entries in the past, you know I've blown up the internal FETs of the DC-DC over five times and spent countless hours reverse-engineering the circuit with experts at work to see just what could possibly be wrong with the system.

I find out this morning from Ross Cunniff (who also recently completed the 914 AC kit), that he has had ABSOLUTELY NO PROBLEMS with his CCPower DC-DC converter. I guess I've been working with a faulty unit for the duration. Since I finished the first kit, Electro Auto didn't want to replace my unit because they wanted me to find out more information before I simply blew up another one. In my opinion, technical support from CCPower was crappy at best. They didn't respond to my e-mails and their response to Electro Auto was along the lines of "there's nothing wrong with our DC-DC converters, it's your problem. We've been doing this for 20 years and know far more than you do."

This frustration led me to do some searching on the internet for other DC-DC converters today and I found one on the EVParts website called the Iota DLS-45. This puts out 45 amps of current instead of the CCPower's 30 amps and costs a third as much. It's slightly larger than the CCPower C400, but still fits in the same space on the front of the battery box. Out of sheer immature emotional spite, I don't want to see another CCPower DC-DC in my EV. The technical support person at Iota was extremely responsive and provided accurate information. I ordered one and it should be here later this week. The added output current should also provide some extra amps for powering a 15-amp 12-volt cabin heater if this cold weather keeps up.

Since I'm on an irritable roll now, I came up with some additional rants about improvements to the 914 AC kit from Electro Auto that I think would be good:

Why not go with the Iota DLS-45 DC-DC if it puts out more amps and costs less?!
If EA provides upgraded suspension parts to handle the extra weight of the batteries, they should also provide upgraded BMW 320i machined calipers to improve braking too. I don't think I could stop this heavy car quickly enough in an emergency situation. The rear shock absorbers also don't have any adjustment to them, so the back end of the car sticks way up in the air.
The Azure Dynamics AC24 motor fits nicely into the chassis, but is way underpowered for the weight of the car. It provides less than 50% of the original ICE power. The 9" DC motor from ElectroAuto's kit 20 years ago provided more torque. This is a Porsche for _____'s sake! Why can't the AC55 motor fit?
Given their lack of response and technical support, ElectroAuto should provide a list of online resources that people can go to for help in 914 conversions. There are many from the 914ev Google group to the 914club.com and 914world.com groups as well as the EVDL.
ElectroAuto scrimped and shipped 2 gauge cable with the AC kit instead of 2/0 gauge cable, possibly thinking that the AC kit would pull less current. It still pulls 300 amps, similar to the DC kit and greatly benefits from the thicker gauge welding cable.
Despite being listed as part of the kit, ElectroAuto provides no hardware (i.e. bolts, nuts, hood pins, etc...). I actually didn't mind purchasing my own hardware, but I had no idea where to get some of the more obscure items. EA should have provided part numbers or sources to buy these extra items at.
I think ElectroAuto should maximize the capability of the internet to help its users and help reduce it's own level of tech support. Provide more FAQ sheets and have an online forum or group so that people doing the conversions can help each other instead of relying on Mike or Shari to answer every single question. I suppose the 914ev Google group is good for this, but having a pointer to it would be helpful.
ElectroAuto should sending out instructions and drawings in .PDF instead of AutoCad .DXF format and MS-Word. Not only would it help everyone viewing it, but it would also protect ElectroAuto's original digital documents. A .PDF print driver is free off the internet.
Helpful hints to the user such as "make sure you rebuild your transmission" and "keep your flywheel when you get rid of the engine" would be most useful.
My biggest beef with ElectroAuto that's tainted me from day one is their lack of accuracy in reporting delivery times. If they had told me directly that first parts would arrive in eight weeks and the remainder of the kit would take an additional six months, I would have groaned but ordered it anyway knowing the wait ahead. This would have allowed me to plan my time accordingly. In reality, I never got a straight answer when parts would arrive and waited anxiously for months expecting parts to show up. I don't see why telling the truth would hurt in this case.

Despite the above rants, the basic kit is good. The quality of the parts is high, especially the battery boxes.

Enough flaming for today. If I can get through the week and get the new DC-DC from Iota soon, I should be back in business. I can actually drive the car without the headlights for quite a while, but with the headlights on, the DC-DC can't take the load and the 12V accessory battery completely drains after 30 minutes.

Grrr.

DC-DC Overcurrent Malfunction

2008-01-27T21:04:00.000-08:00

It's good to get the extra transmissions out of my garage. I guess it's poetic justice that the guy who bought my side shifter from the original car is going to give it to Jeff at Rothsport systems for a rebuild, the same guy who didn't work on it for 2 1/2 months when I gave it to him.... The buyer of the tail shifter transmission is also in the process of doing an electric vehicle conversion, so he asked a bunch of questions about my project.

I've been noticing that my auxiliary battery seems to drop in voltage significantly as I commute to work. After some experimentation today, I found that under a moderate load of 8 amps or so, the DC-DC eventually stops working and fails to charge the 12V battery. I was misled a few times because when I turn off the key for awhile and turn it back on, the DC-DC starts working again for about 30 seconds before stopping.

At light loads the DC-DC keeps working, so I can charge the 12V battery if I just turn on the key (to close the DC-DC relay), but don't turn on any accessories or start driving (thereby pulling current from the motor controller). For the moment, I charge the main pack at work and turn on the key for about an hour before I have to drive home to recharge the 12V battery.

Here are some current values I measured coming from the 12V battery (without the DC-DC in operation) from various accessory loads:

key off - 10 mA
key on (motor controller idle) - 700 mA
parking brake flashing light - pulses of 300 mA
parking lights - 3.7 amps
parking lights and headlights - 9.4 amps
parking, headlights and fog lights - 17.3 amps
left and right turn signals - pulses of 3.3 amps
backup lights - 3.1 amps
parking, headlights and backup lights - 12.3 amps
brake lights - 3.3 amps
CD player - 1.0 amps
climate control fan (low) - 2.8 amps
climate control fan (med) - 4.5 amps
climate control fan (high) - 6.7 amps
defroster (hair dryer) relay - 200 mA

As you might suspect, I'm irked by the DC-DC still not working, but it's probably my own doing given the modifications I made to the controller. I guess it's back to taking the thing apart and adding an increasing load to see when it fails. Argh.

Watt-Hour/Mile ratings and Selling the Trannies

2008-01-25T13:27:00.001-08:00

I dropped off the 914 with Alan at A&P today to upgrade the brake cylinder and do a front end alignment. Brett, a local guy, is going to purchase my two leftover transmissions and Curt from Salem is visiting today to see the car (hopefully back from the shop).

In the meantime, I took some approximate readings from my ammeter and voltmeter as I drove on flat roads this past week. Overall driving at 20mph tends to pull 30 amps at 140 volts. Driving at 60mph (flat road only) pulls 90 amps at 135 volts. This averages out to around 205 Watt-Hours per mile. Paul Jorg asked for this info, so hopefully this is what you were looking for. I suspect that the fluid resistance in the transmission consumes quite a bit of power.

Although I hate to admit it, there's still a faint screeching sound that comes from the transmission when I spin the input shaft with the electric motor. The sound goes away after I drive a block or so, which leads me to believe that the transmission fluid isn't getting into all the bearings it should. The rather frigid mornings probably aren't helping the situation either.

First Day Commuting with the New Tranny

2008-01-22T18:44:00.001-08:00

Today was the first day on the freeway with the new transmission. Other than watching my amperage, I didn't have any issues and the car drove just fine.

Many thanks to all the people who have offered their support during this long wait to get a working transmission. I'm happy to see all the other 914 EVs out there.

On Friday I'll be re-aligning the front end for better steering and replacing the brake cylinder. I have some machined BMW 320i calipers coming in a few weeks to upgrade the stopping power. I'm also thinking about replacing all the rear bulbs with LED lights to save on 12V current. I might possibly purchase a 12V 20Amp heater for the cockpit, but I don't want to stress out the DC-DC converter too much and a 300 weight polar fleece jacket seems to work fine.

The hair dryers do very well in defrosting/defogging the front windshield. The only thing I forgot to do initially was to open the windshield vents by moving the fan lever halfway to the right. Otherwise, the hot air from the hair-dryers doesn't make it up to the windshield (oops).

I might splurge over the next year and purchase an EVision system from Metric Mind to really get a grip on the battery state of charge, but the installed PakTrakr might do just fine. I need to be careful of "feature creep when installing a bunch of new toys on the EV.

I'm in the process of figuring out if there are any tax breaks at the federal and state level for the car. I also still have two leftover transmissions sitting in the garage that I'm trying to get rid of.

I'm really happy to get the 914 on the road given rising gas prices and the economy tanking at the same time. 2008 will prove to be a very interesting year. Best wishes to all.

Up and Running Again!

2008-01-17T22:56:00.001-08:00

My friend Rick and his girlfriend Holly were gracious enough to come over and help me finish putting the transmission back into the car. We worked from 7pm-10:30pm and finished the job.

Here's Rick and I under the car re-attaching the CV joints and getting covered with grease.

Here's Rick and Holly in the working vehicle. We drove the vehicle around the block and the transmission was very smooth. I'm very grateful to Greg Robbins for shipping a transmission in such good shape. No vibration up to 5400 RPM. Big thanks to my friends for all their support during these frustrating times with the transmission.

Tomorrow is my day off and I plan on testing different RPM values above 5400, logging some data with the Pak Trakr and seeing how the car handles.

I'm rather tired to show my relief and enthusiasm in getting the car back up and running. I still need to upgrade the brake cylinder to 19mm and get a front end alignment to help with the tough steering.

Things are looking up. If it works well over the weekend, I'll commute to work on Monday. Hopefully the cold weather won't kill the car. Cheers and Good Night.

Yay! Less Vibration!

2008-01-16T19:50:00.001-08:00

Rather serendipitously, my friend Jonathan dropped by this evening and we joined the transmission to the electric motor and spun it up. I was quite relieved that spinning up the new transmission to 5400 RPM produced little, if no vibration.

We were a bit nervous when we heard a minor squeal inside the transmission case. We then put the transmission into first gear, allowing the fresh transmission fluid to flow from the bottom shaft onto the gears on the top shaft. That caused the squealing to subside.

Here's the transmission mated to the motor. Note the rubber bands on the clutch fork to prevent it from crashing into the spinning flywheel. Jonathan is holding a piece of cardboard over the license plate because the reflection really screws up the light measurement system in my camera, especially when taking pictures at night.

Tomorrow, my friend Rick will help me re-attach everything. For now, I came home exhausted from lack of sleep over the past few nights and I don't want to risk putting this baby back together with only half a brain. I'm "cautiously optimistic" at this point that things might actually work.

Next up: hooking things back together. Good night.

New Tranny Here - Salvaging Cracked Parts

2008-01-15T21:59:00.001-08:00

The newly rebuilt transmission from Greg Robbins showed up via UPS today at 95 pounds.

Here is the plastic tub that it was shipped in. The tub doesn't look like UPS treated it very well.

Another view of the tub. The fiberglass straps are broken, the lid is totally cracked in pieces and most of the corners are dented in.

Here's the transmission removed from the plastic tub in my front hallway with plastic peanuts everywhere. At first glance, everything looks to be in order.

Another side view of the transmission. Pretty clean! The gears feel good and solid if I rotate the input shaft and output couplings.

Oh no! Upon closer inspection, the side-shift support looks like it suffered a rather harsh fall. Note the large crack near the upper left of the picture. The bottom edge of the support looks pretty beat up too, possibly from dragging on the ground. The material inside the crack is very clean, leading me to believe that this was probably caused by UPS, although there was plenty of padding in the bottom of the plastic tub.

Another look at the crack on the side-shift support. I didn't want this liability on the transmission, so I replaced the cracked support with the one from my existing tranny.

I never thought I would have three transmissions in my small garage. I've moved several necessary parts from my original transmission to the newly rebuilt one (on the left), to make it functional.

Tomorrow, I plan to fill it with transmission fluid and see if it bolts to the motor reasonably.

Man, I reallllllly hope this works....

Rebuilt Transmission Coming Tuesday

2008-01-11T14:47:00.000-08:00

I just received an e-mail from Greg Robbins that he shipped a rebuilt transmission to me via UPS and it should arrive next Tuesday! The UPS tracking number concurs with this.

This will be a good time to get back into the swing of things since my girlfriend Krista is starting classes next week and the holidays are winding down. Working in the garage is a bit slow since it's cold and rainy, but I should be able to get things put together.

I want to issue a big thanks to all the folks at 914world.com that expressed support and advice in my pursuit to fix the transmission. The electrical plug-in station at work has been lonely over the past few months and I'll be psyched to get the car back on the road.

About a month ago, I sold my old '94 gasoline Saturn wagon and purchased an '03 Subaru Outback. It's much more comfortable and handles the snow quite well (went snow-shoeing twice), but it's got significantly lower gas mileage (about 26 instead of 32). With gas prices going up, I'm even more eager to fire up the 914.

I'm glad to see Ross Cunniff and Matt Kneipper get their AC 914 conversions on the road as well.

May all have a Happy New Year.

Cheers,
Tim

Snatching the Transmission Back

2007-12-21T13:10:00.000-08:00

Well, I'm back to square one again on the tranny. Rennsport Systems kept my transmission for over two months and didn't work on it. I asked the good folks over at 914world.com about the situation and most people suggested that I was waiting far too long and paying far too much for what I was doing. Two folks highly recommended I go out to the Rennsport shop without calling ahead of time and just take the transmission back, just to be sure they didn't start working on it as I drove over.

So that's what I did. Jeff at the shop was gracious enough to give me back the transmission (and the extra-parts tranny) without any questions. They seemed completely stressed out due to the extreme backlog of work, anyway.

I'm in the process of trying to buy a rebuilt tranny from one of the 914world folks, so I hope that pans out. My other option is to have "Dr. Evil" from 914world rebuild a transmission for me for $1500.

My gut feel, not based on any fact, is that a different transmission won't have the same resonant problem as this one does; however, it may come with its own problems. Stay tuned as the saga continues...

Still waiting for the Transmission

2007-11-25T22:52:00.000-08:00

Well, it's been over a month since I've posted since the holidays are here and I'm still waiting for the transmission to get back. I talked with a guy at Rennsport Systems last week and he said he'd see what was going on and get back to me. Still haven't heard from him. I'll try again tomorrow.

On a more positive note, Ross Cunniff got his 914 AC kit running recently and Bob has been making progress on his BMW 325i performance EV (see links at right).

I also had a phone interview with a journalist named Kristen that I met at NEDRA who's writing an EV conversion article for the February issue of SportsCarMarket.

In the meantime, I'm helping other folks using the AC kits with the Azure Dynamics controller get their systems working. Best wishes to all the EV conversions in progress.

Hair Dryers Installed

2007-10-21T15:30:00.001-07:00

I took a few hours today to get the small hairdryers installed.

In order to have a convenient switch to activate the hairdryers, I hijacked the defroster knob switch. I was lucky enough to have this option on my car. The wires from the defroster knob sit in their own plastic tube, so it was easy to find the yellow/red wire going towards the center wiring column of the car under the clutch pedal. This wire provides 12V when activated, just the thing I need to fire up the 12V DC relay.

Here's the travel hair-dryer attached to the heater intake on the passenger side of the car. The coupling is just short enough to let the hairdryer not interfere with the hood spring. The pipe clamps make the whole thing very snug.

Here's the DC relay mounted on the firewall just behind the middle battery box above the foot pedals. I used two 10-32 rivnuts to bolt this thing in. The two hair-dryers are tied into the terminals on the left. The negative battery cable is on the lower right (black wires) and the upper right comes from the positive battery post in the fuel compartment with an inline 10 amp blade fuse.

Remember the yellow/red wire from under the dash in the top picture? It's tied into the top coil terminal on the relay here. Since the chassis of the car is ground, I simply tied the bottom coil terminal to the mounting bolt (small blue wire).

For testing, I started with one hair dryer on the "low" setting with 5-amp fuse. It ran well (albeit loudly) and provided a slight warming into the cockpit. If I put the hairdryer on "high," the 5-amp fuse blows immediately. The hairdryer is very loud on "high" so I put both hair dryers on their "low" settings and used a 10-amp fuse. I suppose in desperate move to heat the cockpit, I could put in a 20-amp fuse and run one hair dryer on "high" since the high setting pulls about 15 amps. I'll try the "low" settings for now and see how it goes.

Next up: experimenting with an optocoupler to capture voltage for the "fuel gauge"

Serial Port and Hood Pin

2007-10-19T15:06:00.000-07:00

Today was a bit slow. I received some AMP pins in the mail that fit the special connectors on the DMOC445 controller. To make the serial port more robust, I crimped the pins onto the ends of the 16-gauge wires and inserted them into the 8-position connector that came with the DMOC.

Here's the finished connector. It's far more reliable than the simple sockets I had soldered to the end of the cable. See this post for the prior implementation.

I also took a little time to install the hood pin that I got from Schucks yesterday. Drilling a rectangular hold through the engine compartment lid was very tricky. I covered up most of the rough edges with the plate that comes with the hood pin. At least it's a lot nicer than the block of wood I was using before.

Just for grins, I fitted one of the hair dryers to the passenger side heating duct and plugged into the wall outlet to see how well it would heat the car. It's rather loud, but produces a light stream of warm air. I wouldn't use this to fully heat the car, but it'll probably make a decent defroster.

Dedicated Charging Outlet and Hairdryer Coupling

2007-10-16T20:44:00.001-07:00

After sleeping for 14 hours last night, I think I'm somewhat recovered from that nasty cold. I dropped by Parkrose hardware after work and picked up some stuff to install in the EV.

Since I have a gas range, I replaced the 240V breaker for the non-existant electric range with a 20-amp 120V breaker dedicated to charging the 914 EV.

I purchased two small travel hair dryers over the weekend and found some plumbing couplings that seem to fit quite well on both the hair-dryer and the heating system input. I forgot to bring the relay to the hardware store, so I'll probably get the electrical connectors tomorrow and install the system over the weekend.

I also ordered some of the custom sockets that go inside the 8-pin DMOC connector so that the serial port will be much more of a permanent installation instead of just sort of dangling out of the controller.

Big thanks to Ross Cunniff for pointing out that hood pins are available at the local auto-parts store. I searched high and low for these at the regular hardware store but didn't think to look in the "bling" (ahem, I mean performance) section of the auto store.

Running the AC24 at High RPM - maybe not

2007-10-15T18:39:00.000-07:00

I'm still big-time sick today, but recovering quickly. In my efforts to understand the torque of the AC24 motor a bit more, I looked at the datasheet online at Azure Dynamics:

http://www.azuredynamics.com/pdf/AC24%202007.pdf

Hmm, it looks like the optimal operating point is really around 4500 RPM and torque drops off quite a bit at higher revs than that. In my frenzy to go on the freeway in first gear, I didn't really look at the operating characteristics of the motor. Also spinning the input shaft of the transmission above 4500 RPM continuously might wear it out sooner. Oh well, back to bed to recover...

Initial Fuel Gauge Driver Schematic

2007-10-13T11:38:00.000-07:00

Since I'm stuck indoors today to recover from a sore throat, I put together the following schematic to drive the fuel gauge based on the pack voltage.

(Click to enlarge the image)

With the exception of the 4N25 opto-isolator, which I salvaged from a dead UPS, all parts are available at Radio Shack. I hope to implement this soon. Comments and feedback are welcome.

Finishing the Serial Cable and Testing the Fuel Gauge

2007-10-12T18:14:00.001-07:00

I had a bit more time today to work on some other small projects.

Here's the 914 patiently waiting for its rebuilt transmission from Rennsport Systems. It'll be awhile since Rennsport won't start on the rebuild until November.

Up until this point, the serial cable from the DMOC445 AC controller to the passenger seat was routed along the outside of the car. I cleaned this up today by taking out the two seats, pulling forward the upholstery in front of the firewall and drilling a hole for the serial cable. For some reason, I had an extra cap-plug left over from the kit, so I used it to protect the cable from the sharp metal edges. The cable now runs neatly behind the seats and into the central armrest.

I got really upset when putting the seats back in because I dinged the paint near the door handles with the sharp edges from the seat rails. I'll patch this up with touch-up paint, but I'm still frustrated with my clumsiness. Working in this small single-car garage is a challenge.

I also started researching how to drive the fuel gauge with the voltage on the batteries. The fuel gauge reads the resistance of the fuel sensor which varies from zero ohms (full) to 75 ohms (empty). I verified this by shorting out the sensor circuit and putting 75 ohms in the circuit. The system pulls 100 milliamps at zero ohms and 50 milliamps at 75 ohms.

For you electrical engineers out there, I'll probably implement a circuit with a 4N25 optoisolator to measure the voltage on the main battery pack and drive the fuel gauge with an op-amp controlling current through a transistor in emitter-follower configuration. I'll post the schematic here after I get it up and running. There's also a fuel-empty light that I can drive if the battery voltage gets too low or the voltage droops because I've accelerated too long and drawn down the main pack voltage. Any suggestions on how to make this circuit work are welcome.

I started getting a sore throat today, so I'm going to bed early and will probably take it easy tomorrow by working on the fuel gauge circuit. I'd really like to get the hair dryers installed soon so I can drive in the colder weather.

Cheers and good night...

Finishing the Rain Gutter for the Engine Compartment

2007-10-12T18:03:00.000-07:00

The major project of the day was finishing the rain gutter under the engine compartment lid. The original gutter was too deep and interfered with the rear battery box. As described in a previous post, I purchased a piece of ABS plastic from TAP plastics and bent the edges to make a rain catch.

Here's the plastic that I bent a few weeks ago. ABS plastic has the nasty property of deteriorating quickly in sunlight, so I spray painted it with three coats of Krylon black satin paint to protect the plastic. I also drilled holes where the lid mounting bolts were and cut out the bottoms of the drain wells on either ends.

Here's the plastic installed on the underside of the engine compartment lid. There are three bolts on the top edge that hold it on. The bottom edge is held on by sliding it under the horizontal support beam. I used silicone caulk to seal the three bolts to prevent leaks.

Since the new rain gutter sits much higher than the old one, I added some cheap 99 cent funnels from the hardware store and cut them so that the top was level with the ground. The larger funnel input area also allows the downspouts on the gutter plastic to be slightly off center in case I goofed up a bit.

Here's the engine compartment lid re-installed. I also cemented two small rectangles of plastic under the mesh to either side (see small red C-clamps) to help drain rain away from the circuitry in the engine compartment.

After the cement on the small side pieces was dry, I was able to close the hood as shown above. ElectroAuto still hasn't delivered the hood pins and I suspect that I'll never see them at this point, so I'm still using a small square of plywood to hold the lid shut.

Giving up the Tranny to a Higher Mechanic

2007-10-10T10:17:00.000-07:00

After receiving admonishment from two mechanics about driving around with a resonant frequency, I dropped the transmission out of the 914 and gave it to the experts at Rennsport Systems this morning for a precision overhaul. This is the fourth time dropping the motor/tranny, so I was able to do the whole process in less than an hour. Giving up the tranny was an ego battle for me because I had spent so much time rebuilding the transmission in the first place.

Rennsport deals with racing Porsches, so I suspect I insulted their intelligence when I said the electric motor only puts out 72 ft/lbs of torque and rattled at a "low" RPM of 5400. Anyway, my time is getting more valuable these days and I just want this thing working. They said they'd get to it at the start of November. I've got hairdryers and a fuel gauge to work on in the meantime, possibly even an MP3 player...

On the Road Again

2007-10-08T19:31:00.000-07:00

I started commuting to work again today. I think the transmission is making slightly more noise than before but otherwise the car is fine. The RPMs are limited to 5300 RPM, so I won't have any resonant activity. I'm really happy that the tachometer is hooked up. It really helps me keep tabs on what happens to the motor/transmission at different speeds under different driving loads. It's also much easier to watch than the speedometer hidden behind the right edge of the steering wheel.

The car also seems to be unaffected (so far) by driving in the rain. We'll see how long that lasts. I do have issues if I get in the car all wet from running through the rain, since my body heat evaporates the water and fogs up the windshield. Turning up the vent fan on full helps quite a bit, but having the hair dryers will definitely help.

I called Rennsport Systems to ask for a transmission rebuilt quote and they suggested budgeting between $2000 and $3000 for parts and labor (Ouch!). Alan at A &P quoted about $425 for labor plus parts (better). I could also get a transmission off e-bay for about $375 plus shipping. With the spare parts I can salvage from the second transmission, I'm thinking that having Alan do a rebuild would be the best thing.

My plan is to drive the car for a week, show it off at the EV meeting on Thursday and take it in to Alan on Friday (if he has time) to upgrade the brake cylinder and align the front end. We can chat about the best direction for the transmission from there.

Perhaps I'll work on the fuel gauge in the meantime.

Thoughts at the End of the Day

2007-10-06T17:41:00.000-07:00

Well, the car is all back together again. I really can't say it's any better than before; however, I've learned a tremendous amount in the process. After balancing the flywheel twice, adding rubber grommets, replacing the transmission mounts and putting in a new pilot bearing in, I still can't get the vibrations to go away or diminish much.

Given that the second transmission didn't vibrate much at all, even over 7000 RPM, I'm really suspecting the existing transmission has a bent shaft in it or something. There's definitely 10 mils of runout on the input shaft, but I didn't think that would be a big deal. If I look back over my transmission rebuild at the link here, I remember that the bearings in the transmission were shattered. I never really understood why and just replaced the bearings. Perhaps one or both of the shafts were bent already and caused the bearings to break. I'm also guessing that running the transmission through its natural resonant frequency several times over the past week wasn't good for it either. I might be able to salvage a straighter shaft from the second transmission, but I don't know if they are different between the side-shifter and the tail shifter version. The next step is to drive around a bit more and see what happens. Perhaps the transmission will fail, but who knows.

Since the RPM gauge and indicator lights are working, I'm thinking about driving the fuel gauge with an opto-isolated circuit from the 144V pack. It needs opto-isolation so that there are no connections between the 144V system and the 12V system. I'll post that circuit if and when I get it working. Best wishes to all the other EV folks working hard out there to get their cars running.

Replacing the Pilot Bearing

2007-10-06T09:50:00.001-07:00

I purchased a new pilot bearing for the flywheel to see if replacing it would help with the rattles.

Flywheel - it's what's for dinner! I've found during my transmission rebuild that heating up components in the oven (200 F) sometimes helps with removing the bearings, so I heated up the flywheel prior to replacing the pilot bearing. I also put the new pilot bearing in the freezer to make it smaller.

Here's the heated flywheel, clutch side up. I put a 9/16" socket on the pilot bearing and placed a steel block over that to even out the pushing forces. After a few good whacks, the bearing popped out.

Here's the re-installation. Again, I put the new bearing in the freezer to help it go into the hot flywheel easier. I first tried to line the new bearing up and used the steel block to keep it straight while I tapped it in. I used the 9/16" socket again to finish the job.

I searched online to see which way the bearing went in. The one comment I found online said that it didn't matter; however, if I look at the bearing, one side is clearly wider to present the needle rollers to the incoming shaft. I chose to install the bearing with the embossed text on the rear (non-clutch) side to see if that would help.

Getting the Tachometer and Lights Working

2007-10-06T09:02:00.000-07:00

After receiving an updated .css file (ccShell config file) from Azure Dynamics for the DMOC445, I was able to access the EE1SpeedoDiv variable. After setting this to a non-zero value, I attached a scope to pin 25 of the main DMOC connector and (yay!) got a pulse train corresponding to the RPM of the motor.

Here's the pulse train on the oscilloscope. It has a 50% duty cycle and swings the full 12V range. This makes it ideal to drive the 914 tachometer.

Since pin 25 wasn't one of the original wires brought out of the wiring harness by Electro Automotive, I had to modify the DMOC445 connector. This proved to be easier than I thought. Since I had modified the regenerative braking system to not drive the brake lights, I had three extra wires left over. I'll use these to tap into DMOC monitoring functions to drive the tachometer and the red/green indicator lights on the dash.

Here's the main DMOC connector removed from the DMOC. To open up this connector, I used an icepick to lightly bend aside the two small black holding tabs on either end. It was then relatively easy to pop off the red cover.

Here's the same connector with the red cover popped off. You can see the pins that were previously installed by Electro Auto. If you use an ice pick to pry apart the two holding tabs under any pin, that pin will release and slide out the back of the connector.

With my prior modifications, I didn't need the blue, yellow, black/yellow or brown/blue wires, so I pulled them out of the connector and put them back in to new places. Note that your colors may be different from mine. I kept the black/yellow line at pin 19 to act as a ground. I put the blue wire to pin 11 (the READY led) and the yellow wire to pin 34 (the FAULT led). The brown/blue wire went to pin 25 (SPEEDO_BUF) to drive the tachometer.

Now, I was concerned that the tachometer would pull way too much current and possibly short out the DMOC driving signal, so I created a simple 555 timer circuit to drive the tach input signal (black/purple wire in the main wiring harness). The 555 timer doesn't drive that hard and I didn't see any degradation in its output signal. Given that, I simply tied the SPEED_BUF signal from the DMOC directly into the tachometer input wire and (voila!) the tach started working!

Here's the tachometer at around 2600 RPM. I had to adjust the EE1SpeedoDiv parameter inside the DMOC so that the tachometer matched the ISR2Hertz RPM value shown on the laptop. My calibration value for EE1SpeedDiv was 70, but that might vary with different gauges.

Next up was tying the READY and FAULT output lines into the green oil light indicator and red generator light indicator. The original kit doesn't use the red light and the green light is simply grounded. The READY/FAULT output signals on the DMOC are unbuffered 3.3V digital logic outputs. Since the indicators on the dash already have one side tied to the 12V supply, I simply used a 2N2222 transistor (buy a pack of them at Radio Shack) to drive the two indicators. The 3.3V DMOC signals drive the base of the transistor through a 1K ohm resistor. The collector is tied directly to the indicator light and the emitter is tied to ground. When the signal goes high, the transistor turns on, pulling current down through the indicator bulb.

Here's my simple test setup. I just used simple alligator clips to attach everything. By trying different resistor values, I found a reasonable base drive resistor empirically that doesn't load down the DMOC signal but still provides enough current to turn on the transistor.

After making the test circuit, I took a breadboard from Radio Shack and soldered all the components together with some quick-connect solder connectors. The circuit worked fine and the two dashboard indicators now show all the codes that were listed in a previous post.

Here's a simple schematic to show how the transistors and tachometer are hooked up. Click to enlarge the image.

Next up: replacing the pilot bearing in the flywheel and putting the whole thing back together.

Trying a Different Transmission

2007-10-05T18:14:00.000-07:00

Last week Craig at Camp914 offered to lend me another transmission to see if I had vibrational issues.

I drove out to Camp914 this morning. I wish to express much gratitude to Craig for letting me borrow this spare tranny. Since it's an older tail-shifter and many of the external pieces are missing, he even gave it to me.

Here's my test setup again. The working transmission is tied to the motor at left and resonates at 5400 RPM.

Here's the alternate transmission. Again, I don't have the clutch friction disk installed, so the only thing that the flywheel is touching is the input shaft inside the pilot bearing.

The moment of truth: After spinning up the system past 7000 RPM, I got no vibration whatsoever. Rats, there must be something up with my own transmission. I suspect that there's something up with looseness in the transmission shafts or perhaps rattling in the pilot bearing. I got a new pilot bearing yesterday so I'll see if that helps. It looks like this is an isolated case and not everyone will have this resonance. I wish all the other 914 AC kit owners luck.

Just for yucks, I pulled out the lower transmission fluid plug on the second transmission. The lower plug has a built-in magnet to pull out all the metal shavings floating around in the fluid. This plug was completely packed with metal shavings. One of the common hacks you can do if you have a disposable second transmission is to put the bottom plug from the second transmission in the top hole of the first. That way you have two magnets pulling metal shavings out of the fluid for you. This plug also had a hex head on it (instead of a hex depression) which makes it much easier to unscrew when you need to replace the transmission fluid. I think I'll keep it...

Next up: Getting the tachometer and warning lights on the dash tied into the DMOC445 controller.

Note: Ross Cunniff is burning the midnight oil over at http://volt914.blogspot.com/
to try and get his 914 AC done this weekend. I wish Ross the best in getting the second 914 AC kit on the road!

Getting Expert Advice on Resonance

2007-10-01T19:43:00.000-07:00

After spending most of yesterday researching machine resonance, I chatted with one of the mechanical engineers at work today about the resonance problem. After drawing a picture of the motor/transmission assembly, it became rather obvious to both of us that we have the equivalent of a vibrating violin string. The motor/transmission is attached to the car somewhat rigidly at both ends. The main excitation mass in the system is the flywheel, which sits very nicely right in the middle of the structure. At the natural resonant frequency of the system, the tiny vibrations from the flywheel shake the center of the assembly up and down, just like passing a violin bow over a string.

Since the natural frequency of the system is sqrt(stiffness/mass) and mass is rather hard to change, he suggested adding stiff support bars to the bolts on the adapter plate and bolting the other ends of the bars to strong parts of the car chassis. This would increase the stiffness factor and raise the resonant frequency. This is similar to placing your finger in the middle of a vibrating violin string and having the frequency jump up an octave. The string still vibrates, just at a much higher frequency.

He did lend me an accelerometer which I tied to my analog oscilloscope to measure the three degrees of motion on the motor housing. I didn't get very accurate measurements because I didn't want to hold the system in resonance for too long, but it was good to see that the system underwent 5-6 Gs (5-6 times the force of gravity) during its oscillation at resonance.

On a slightly different note, I also probed the encoder signals inside the position feedback box attached to the DMOC445. In case I can't get a speedometer signal out of the DMOC, I just might risk tapping into the position encoder. It seems like a much easier idea than adding an opto sensor on the flywheel. The pulses coming out of the position box are close to a 50% duty cycle and we get 64 pulses per revolution of the flywheel. This is not surprising since the EE1EncoderPulses variable in the DMOC445 is 64.

At this point, I'm thinking of giving up and just limiting the RPM to 5400 and looking at ways to add support bars to the motor adapter plate later. I just want to get this thing going again.

Cheers,
Tim

More Resonant Experiments

2007-09-30T19:48:00.000-07:00

My friend Rick dropped by tonight to run the accelerator cable and monitor the RPM on the laptop while I put my hands on the motor/tranny to get a better feel for what's going on. We ran the motor with the transmission attached for weight without the clutch friction plate. I also put the transmission in first gear to guarantee that the input shaft was not turning and contributing to any vibration.

I short, we experienced a classic resonance in the system as described well in the following link:

http://www.dliengineering.com/vibman/resonance.htm

The motor/transmission behaved just like the amplitude graph in the link above. We got a resonant frequency at 5450 RPM and the vibrations remained but at a much lower amplitude above that, all the way up to 9000 RPM.

One funny thing to note is that without the clutch friction disk in the system, there is very little play in the clutch fork. If I pull it towards the rear of the vehicle, it tries to depress the clutch, but I don't have the strength with my hand to move it. Just for yucks (DON'T TRY THIS AT HOME KIDS!), I lightly pushed it towards the front of the vehicle and it hit the face of the clutch pressure plate while it was still spinning! Yikes! Against my better judgement (engineers try these things...) I used the clutch fork to monitor the status of the flywheel while the system hit resonance by verrrry lightly touching the spinning clutch. During normal operation (say 3000 RPM), I felt a uniform depth all the way around the clutch. During resonance, the face of the clutch seemed to oscillate rather significantly with the "beats" of the resonance. See the following link:

http://www.dliengineering.com/vibman/beats.htm

Just to get a good comparison, I removed the transmission again and got no vibration from 0-8000 RPM (just motor, adapter, flywheel and clutch pressure plate).

As before, I'm a bit confused about what to do at this point. I'm imagining that Azure Dynamics didn't take into account that the system would have the cantilever of a transmission attached to it, especially a Porsche 914 transmission. I believe that Electro Automotive didn't prototype this motor/tranny configuration, so they probably didn't bump into this issue.

Craig out at Camp914 said he had a spare 914 transmission sitting in his garage that I could borrow to see if a similar mass causes the same issue. I'll probably borrow his transmission and see if I get the same result. If so, there's probably not much I can do except limit the RPM of the system to 5300 RPM and take the performance hit. If his transmission works fine, I might talk to him about swapping it. My doesn't leak a drop of fluid and shifts quite well after the rebuild.

Even with lots of damping devices such as new motor mounts, running the system through its natural resonant frequency is a really bad idea since the system will probably fail quickly. I'll be posting a question to the 914ev discussion list to see if anyone else has spun up their system.

I still might borrow an accelerometer from work tomorrow and log a bunch of data with the audio input on my laptop. Using the audio inputs on the laptop to capture a .wav file and then running an FFT with audio software on the file would definitely show some interesting stuff.

Just another side note: I believe the resonant frequency was actually at a lower RPM with the original flywheel before I had the teeth and backside ground off, so I would think others would hit this too.

Doing Vibration Research

2007-09-30T09:31:00.001-07:00

At the suggestion of Paul J, I started doing research on vibration analysis today. There are several online tutorials regarding vibration analysis. I'm currently reading this one:

http://www.dliengineering.com/vibman.htm

This paragraph taken from the "Natural Frequencies" section is somewhat noteworthy:

'The multitude of spring-mass-damper systems that make up a mechanical system are called "degrees of freedom", and the vibration energy put into a machine will distribute itself among the degrees of freedom in amounts depending on their natural frequencies and damping, and on the frequency of the energy source. For this reason, the vibration will not be uniformly distributed in the machine. For instance, in a machine driven by an electric motor, a major source of vibration energy is residual imbalance in the motor rotor. This will result in a measurable vibration at the motor bearings. But if the machine has a degree of freedom with a natural frequency close to the RPM of the rotor, its vibration level can be very high, even though it may be a long distance from the motor. It is important to be aware of this fact when evaluating the vibration of a machine -- the location of the maximum vibration level may not be close to the source of the vibration energy. Vibration energy frequently travels great distances along pipes, and can wreak havoc when it encounters a remote structure with a natural frequency near that of its source.'

Based on the paragraph above, I suspect that the AC motor is providing a small excitation around 5500 RPM and that is causing major vibrations out in the extremities of the transmission. The transmission mounts are original and cracked, so replacing those might help a bit.

One of my coworkers said he would let me borrow an accelerometer to attach to my oscilloscope. I'll probably take him up on the offer and see what I can find.

Resonant Frequencies

2007-09-29T15:27:00.000-07:00

After successfully spinning the flywheel and pressure plate at 9000 RPM, I felt confident that things were looking good with the motor. I re-installed the clutch friction disk and bolted on the transmission. After spinning up the system, it started rattling and skittering across the floor around 5500 RPM. Geez. This is a royal pain.

After pondering this a bit, I tried the following experiment: I unbolted the transmission, removed the friction disk inside the clutch that attaches to the transmission shaft and bolted the transmission back on. After revving the motor up to 5500 RPM, whole thing still vibrated.

So, by just spinning the motor, flywheel and pressure plate at 5500 RPM, I get no vibration. By simply attaching the mass of the transmission (again, no friction plate in the clutch), I get vibration. Resonant frequencies anyone? I'm guessing that the added mass of the transmission brought down the resonant frequency of the system from above 9000 RPM down to 5500 RPM. There also may be some loose parts in the transmission that resonate at 5500 RPM and cause the assembly to vibrate.

I'm somewhat uncertain what to do at this point. I can put the car back together, program the AC motor controller to limit my RPMs so I never get into the resonant zone, and drive on with reduced performance. The other option is to find a new transmission (or borrow one) and see if it has the same resonant problems. Given all the effort and money I put into this transmission, I'm not looking forward to dealing with another one.

I suppose I could try adding some resonant dissipation material (like a dynamat) to as many places as I can on the motor/tranny to dampen things out. I don't know if materials like this would be able to dampen things enough. I'm probably going to sit on this for a bit... Rats.

Hub is back but EE1SpeedoDiv is not there

2007-09-28T17:44:00.000-07:00

Today had some ups and downs. I got the adapter hub from Electro Automotive back today. I installed it on the motor shaft and, to my delight, it had less than 1 mil of runout and wobble! That's how the hub is supposed to work. I put the flywheel and clutch back on and spun them up to 6000RPM without much vibration, so things are looking better.

Before I mated the motor to the transmission, I wanted to try out the SPEEDO output on the DMOC445 that Beth at Azure Dynamics talked about in the previous post. I was really happy to hear that there's an RPM signal I could tie into. So, I got out the oscilloscope and tied it to pin 25 (SPEEDO_BUF) on the DMOC445 and spun up the motor.

Wait a minute, there's no pulses coming out. The signal is at ground. Azure said it was a push-pull circuit. The documentation said it was an open emitter output (implying a transistor that pulls up to 12V). Perhaps I didn't properly set the EE1SpeedoDiv variable in the controller. Okay, fire up the laptop and tap into the DMOC --- There's no variable remotely close to the name EE1SpeedoDiv! Argh! It's too bad that it's late Friday since the folks at Azure have already gone home, but I'll fire off an e-mail anyway and see if Beth will respond on Monday.

In the meantime, I have a (hopefully) working adapter hub and I can put the car back together and drive it. Perhaps I'll run down to Radio Shack and get an infrared emitter/receiver pair of LEDs to see if I can generate my own RPM pulses. I get frustrated when my hopes are dashed based on expectations. I guess that's just human. Ugh.

An E-mail from Azure Dynamics about the DMOC445

2007-09-21T09:27:00.000-07:00

I recently sent off an e-mail to Azure Dynamics, the maker of the DMOC445 AC motor controller in the 914 kit. I asked how I could tap into the motor encoder signals to create an RPM signal for the tachometer on the dashboard. It turns out that the DMOC controller already has a PWM (Pulse Width Modulated) output that can be used for this. There are also some LED signals that display system status without having to use the serial port.

I would like to express my sincere appreciation for all the tech support that Azure Dynamics has provided. Beth Silverman, the support person, has been very quick to respond with whatever information she can provide from the controller designers. Here's the e-mail:

9/21/07

Hi Tim, inserted below in blue are our answers to your questions. I understand you've been communicating with Randy Pollack; is it ok if I pass your questions on to him along with our answers?

Thanks

Beth Silverman

*******************

From: Tim Kutscha [mailto:tim_kutscha@yahoo.com]
Sent: Monday, September 17, 2007 8:34 PM
To: Beth Silverman
Cc: tim_kutscha@yahoo.com
Subject: Re: tapping into the encoder signals to drive the RPM gauge

Hi Beth,

I hope you had a good two days off last week. Thanks for the info on the SPEEDO_BUF output on the controller. Since this wasn't listed in the Pedal_Controlled_DMOC445_User_Manual_v3.pdf file, I didn't think it was active. From your e-mail, it sounds like the SPEEDO_BUF output is active on my pedal-controller DMOC.

Feature is active on both pedal and CAN controlled

From one document it says the signal is 12V open-emitter. I'm guessing its a PWM (pulse width modulated signal) that pulls an external resistor up to 12V through a transistor. Is this true?

SPEEDO_BUF is push-pull 12V, and it is a frequency modulated signal.

Is the SOC_BUF signal also active on my DMOC445? What is the format of its output? PWM? Does it get its state from the battery voltage or does it require the amp-hour counter to be attached?

Not active

Do the amp-hour counter input/outputs work? If so, do you sell a device that I can connect to them?

Not active; we do not sell amp-hr meters.

Do the BRAKE_PEDAL,BRAKE_LO inputs work? If so, what is the proper potentiometer to attach to them?

Not used

Is there any customer useful behavior on the ANAIN3/LED_OVERTEMP, ANAIN2/LED_MALFN, NONISO_ADIO1, NONISO_ADIO2, ANAIN1 or ANAIN0 signals?

LEDs are 3.3V (unfused outputs). If an LED is connected to it, a current limiting resistor is needed.

LED0: Fault-Signal on pin 34:

- (________): off = no fault

- (_______x): one short blip = motor overheating

- (_____x_x): two short blips = controller overheating

- (___x_x_x): three short blips = motor and controller overheating

- (_x_x_x_x): continous blink = not implemented

- (xxxxxxxx): continous on = powerstage fault

LED1: Ready-Signal on pin 11:

- (________): off = controller disabled (pin 8 = low; or pin 8 = high and pin 30 = high)

- (_______x): one short blip = controller enabled, but pre-charging

- (_____x_x): two short blips = controller enabled & pre-charged, but interlocked

(for example due to gear-selector being in forward at powerup)

- (___x_x_x): three short blips = N/A

- (_x_x_x_x): continous blink = relay closed, but power-stage in fault state

- (xxxxxxxx): continous on = ready (relay closed, power-stage disabled or enabled)

The car is basically running at this point and I'm try to activate as many gauges as I can. Thanks for all your time on this.
Have a great week!

Tim

----- Original Message ----
From: Beth Silverman
To: Tim Kutscha
Sent: Monday, September 17, 2007 10:26:05 AM
Subject: RE: tapping into the encoder signals to drive the RPM gauge

Hi Tim, sorry, I was out Thurs and Fri. Are you already using the DMOC output signal -- it can be adjusted with the parameter called EE1SpeedoDiv ?? It doesn't work with all speedos/tachs, but we have had luck with the Siemens VDO "Cockpit" series, 85mm. Please see

http://usa.siemensvdo.com/NR/rdonlyres/2B56C91E-EE58-45C6-9A1B-DB89524EA0DC/0/ProgrammableSpeedometer.pdf

Regards

Beth Silverman

*************

Getting the Heater Relay and Sending Back the Hub

2007-09-19T19:50:00.001-07:00

Rats. After putting the adapter hub from Electro Auto onto the motor shaft no less than twenty times, I'm pooped. I tried filing down several different faces of the hub to get the runout and wobble down and failed. It's going back to EA tomorrow morning for a new one. I'm thinking that attaching the flywheel shouldn't be this hard.

The flywheel and clutch assembly has been balanced by two different shops and the second shop said the first shop did a fine job, so I'm pretty sure it's not the flywheel.

The bearing on the AC24 motor just behind the adapter hub was squealing ever so slightly when I spun the motor up, so I fear the vibrations might have damaged the motor. Perhaps against my better judgment, I sprayed WD-40 into the bearing and the squealing stopped. I'll contact Azure Dynamics to see if there's a particular lubricant I should use. I thought these things were supposed to be sealed...

On a slightly lighter note, the high-current DC relay for the hair-dryer defroster system came today.

Here's the 125VDC relay. Notice the magnet in the center of the relay. The field from the magnet is used to blow out the arcing from the DC current when the contacts open up. With an AC circuit, the zero-crossings of the voltage allow the arcing to stop; not so with DC current.

Off to package up the adapter hub... (sigh).

Addendum: For those of you who wish to order one of these relays, you can get them from Newark: www.newark.com
Type prd-11dh0-12 in the search box and the relay should display (one leaded and the other lead-free).

Balancing the Flywheel...Again

2007-09-17T17:35:00.000-07:00

I took the flywheel/clutch to Dan Halls Machine Shop this morning and just picked it up half an hour ago. Dan basically said that it was fine. He spun it as fast as the machine would go and it was only out of balance by 2 grams on the flywheel and 2 grams on the clutch pressure plate. Apparently this really isn't a lot for flywheels.

The motor adapter hub from Electro Auto still has 4 mils (thousands of an inch) runout, so I'll try to attack that next. Dan suggested that I try attaching the hub without the shaft key to see if the runout goes away. That way, I can see if I need to modify the inner cone or just the shaft key or its slot.

On a brighter note, I got an e-mail from Beth at Azure Dynamics mentioning that there was an RPM output on the DMOC445 controller that I might be able to tap into and drive the RPM gauge with (given some external converter circuit). There's also an SOC (state-of-charge) output and amp-hour counter inputs that I might be able to try out as well. There's no documentation on these pins, of course, but I'm happy that they're there to try out.

Next Up: fixing the tiny (4mil) runout on the adapter hub...

Those (Not So) Good Vibrations

2007-09-15T18:46:00.000-07:00

Well, it's time to bite the bullet again and see what I can do about the car vibrations. My friend graciously helped me remove the motor/tranny from the car again this morning and assisted with crude vibration measurements.

We removed the motor/transmission from the car and re-attached it to the AC controller wires while on the ground. After spinning up the assembly to approximately 5000 RPM, the whole assembly started vibrating across the floor like those toy footbal players on the vibrating table.
I guess this is good because we can replicate the problem with the unit outside the car.

For those of you who aren't into car mechanics much, I'm going to use the following two terms: runout and wobble. Runout is the change in distance between the axis-of-rotation of a spinning disk and the outer diameter of the disk. Wobble is the change in distance on the front face of a spinning disk near the outer edge.

The next step was to remove the transmission and just spin the motor with the flywheel and clutch assembly attached. This vibrated across the floor as well, but not as strongly. We did notice that the tines on the clutch pressure plate wobbled around. The outer edge of the clutch pressure plate also experienced significant runout during a spin.

This actually concerns me quite a bit. The outer edge of the flywheel looks very smooth with little runout, but perhaps the person who machined off the teeth didn't get the outer edge centered well.

We then took off the clutch assembly and did some slightly more accurate measurements. After spinning the flywheel up to 9500 RPM, we let the flywheel slowly decelerate to zero and took note of the RPM ratings that we felt vibrations at. With just the flywheel, we got vibrational peaks at approximately 1500, 2900, 4400, 6100, and 7400 RPM. As you can see these are all somewhat integer multiples of 1500 with higher harmonics. The largest spread of bad vibrations existed in the 4000-5200 RPM range which correlated with the RPM of the car shaking.

After taking off the flywheel itself, we just spun the motor with the adapter hub on it (see picture below). While the vibrations were much, much less, we still felt measurable buzzing around 1700, 2600, 4900 and 6300 RPM. This is vaguely unsettling that the Azure Dynamics motor would exhibit vibration without any major weight attached. I suppose it's possible that the weight of the flywheel could have hurt the motor shaft bearings at these RPMs, though.
Also, keep in mind that the ISR2Hertz RPM gauge on the laptop from the DMOC controller probably had a 0.5 to 1.0 second delay from actual value to read value, so these RPMs may be off.

Here's the final mess after removing the components from the car. I'm not sure where to go from here since the vibrations got progressively lighter as I removed components. I was able to spin the flywheel and AC motor up to 10,500 RPM without getting major vibrations, but these smaller vibrations might be amplified when the clutch assembly and transmission are attached.

My plan is to take the flywheel/clutch to Dan Hall's Automotive Machine shop and have him rebalance it. (He's the only shop in town with a small enough shaft to fit the VW/Porsche flywheels). After that, I hope to put the flywheel back on in several positions on the adapter hub to see if I can cancel out as much of the runout and wobble as possible.

The current runout measurements on the adapter hub are still 4 mils and the wobble is about 1 mil. Perry Harrington, the machinist who created the Electro Auto adapter hub called me last week and suggested getting a brass hammer and tapping the flywheel on moderately tight flywheel bolts to eliminate the runout. I'll keep y'all posted as I get the flywheel back from the balancing shop...

Keeping the Rain Out

2007-09-15T18:26:00.000-07:00

Since I live in the Pacific Northwest, I get rather concerned that rain entering the engine compartment will cause problems with the electrical wiring. Many other 914 EV'ers have protected their wiring inside conduit boxes and other shields. I just following the ElectroAuto directions and bolted the relays and terminals blocks to the engine compartment wall with wires dangling from them. This is an idea I came up with to help protect the components.

This is the engine compartment cover removed from the car. I still have the downspouts from the original car, but the original gutter that captured rain from this mesh opening was too large and interfered with the rear battery box.

I drove over to TAP Plastics and purchased a 12"x48" piece of black ABS plastic (for $4.00) to make my own rain gutter. The stuff is remarkably moldable with a heat gun. After making some measurements, I heated up the edges to make a lip for the rain to fall into.

The melting process is basically this: sandwich the plastic between two 2x4s, heat up the protruding plastic with a heat gun and use a third 2x4 piece to bend it down. You need to hold it in place for a few seconds otherwise it tends to bounce back to its original shape.

After melting the bottom and left/right edges, I made a cutout to fit around under the metal pieces to give the plastic shelf a downward slope towards the rear of the car.

Here's a closeup of one end of the finished plastic gutter that goes under the engine compartment hood. I heated up the upper right corner that goes over the downspout and used the end of a screwdriver handle to push the melted plastic into the mouth of a jar to create a depression for the rainwater to flow into. I'll cut a 1/2" hole in the bottom so that the water drains into the downspout. The slot at left (along with the barely noticeable horizontal cut) will fit around the metal struts under the compartment lid.

To hold the bottom edge into place, I'll purchase some short 6mm bolts with large heads to attach the plastic to the original gutter mount holes. My friend wisely pointed out to me that ABS plastic decays quickly in directly sunlight, so I'll probably end up spray painting the surface with an oil-base black paint to prevent the plastic from degrading.

Two Week Commuting Report

2007-09-13T21:32:00.001-07:00

Since I don't work Fridays, this is the end of my second week commuting to work fifteen miles each way. Two things have definitely made the car more fun to drive. 1. The batteries are broken in so I have more current to work with and more importantly 2. I've learned some of the tricks to driving the car.

The biggest trick involves starting from a dead stop. Apparently, the AC motor feels like it has more torque at non-zero RPMs (perhaps just a false perception). However, if I start from a stoplight in the same way as a gasoline vehicle (rev the engine and slowly let out the clutch), I can start much more quickly than if I just leave the clutch out and floor the accelerator from a stopped motor. The same thing helps when starting from stopped on a hill.

With the charger plugin at both work and home, the PakTrakr fuel gauge doesn't seem to drop below the 80% mark, so I think the batteries will last a little while. The DC-DC converter is still working fine, so the car is actually quite convenient to drive. I haven't touched my gasoline car in two weeks now.

Sooooo, with everything working reasonably well------ it's time to drop the motor/tranny again and revisit the flywheel vibrations again. (doh!) I called around to several Porsche repair shops and finally found Dan Hall's Auto Machine. Apparently Dan is the only guy in the Portland area that has a flywheel balancer with a small enough mandrill to fit the 914 flywheel hole (1/2 inch or so). While I hesitate to dismantle a working car, I'd really like to rev the motor safely up to 7000-8000 RPM to get more torque and run the car on the freeway in second gear (!).

I contacted Azure Dynamics and asked them how I could measure the RPM on the motor so I could drive the tachometer in the middle of the dash. They strongly recommended against tapping into the encoder signals since they had noise issues themselves with the encoder signals. With the motor out, I'm going to look into RPM kits for electric cars that use spinning magnets on the flywheel with a magnetic sensor to generate a signal. Stay tuned...

A Response from CC Power on the DC-DC

2007-09-11T22:26:00.001-07:00

I just got an e-mail back from Electro Automotive from CC-Power regarding the failed DC-DC converter. I prefer not to comment on it but simply wish to pass it on to others who might have wondered what the manufacturer said. Here goes:

"The converters have been manufactured for over 20 years and we have 10,000+ units operating in South Africa at 120 volts, all using the same build, without any problems.

"The existing current limit system operates on a pulse by pulse basis and shuts the converter off immediately current exceeds a safe level. The method Kutscha is using has been tried and thrown out as it is not fast enough to protect the devices in an over-current situation. It also effects the transient response of the converter, causing the voltage to dip when load is increased and overshoot when load is removed."

"The problems he is experiencing are almost certainly voltage related than high current and are due to his installation, rather than the operation of the converter."

"The converter should be connected directly to the battery terminals. if he is connecting to the controller terminals, the problems of over voltage during regeneration will be much greater."

(okay one comment: no wonder the parts in this unit are so ancient! 20 years?!)
Cheers,
Tim

DC-DC Seems to Work!

2007-09-09T21:10:00.000-07:00

I just drove home from a meeting for half an hour with the headlights on. In the process of driving, the brake lights and turn-signals were also on. This is the first time I've arrived home with the DC-DC converter still working! Yay! I'm going to give it a week and see if anything else causes a failure. In the meantime, I'm going to report my findings to CCPower and Mike at ElectroAuto so perhaps they can modify the design.

Many thanks to all of the analog EE types out there who offered assistance in helping me understand just what the heck was going on with this thing. I've learned a tremendous amount about switching power supplies, shunts, protection circuits and over-current sensors.

If all works out this week, I'd like to start working on two fun things. The first is a simple op-amp circuit that drives the analog fuel gauge to show the pack voltage (maybe swings from 120V to 155V for a nominal 144V pack?). The second is an opto-isolated circuit to capture the encoder pulses off the AC motor to drive the large RPM gauge in front of my nose that doesn't seem to do anything. Let's cross our fingers and hope the DC-DC holds out.

Cheers,
Tim

DCDC Transistor Hack

2007-09-09T15:22:00.000-07:00

After talking with various people and realizing that the over-current circuitry was making the FET gate pulses way too large, I decided to hack the DC-DC converter circuit.

Here's the new circuit (click to enlarge). I swapped out the IRFP350 FETs with IRFP460 FETs which have a higher voltage and current rating. To compensate for the larger gate capacitance and speed up the rise/fall time of the FET gates, I lowered the gate resistance from 27 ohms to 15 ohms.

The biggest hack, though, is tying the nShutdown pin to ground (disabling it) and adding a 2N3904 NPN transistor to bleed voltage off the soft-start capacitor when current is sensed too high. This makes a crude overcurrent sensor that limits the FET gate pulse without all the problems with pulsing the nShutdown pin. I adjusted the "amp adjust" potentiometer and was able to get the FET gate pulse to shrink if too much current was pulled.

Here is the top of the board. I've tied the emitter and collector of the 2N3904 to the leads of the soft-start capacitor. The base of the transistor is stretched to the left and goes down through a hole I drilled in the printed-circuit board.

Here's the back side of the circuit-board. I kept the .01uF capacitor to filter out the pulses on the current sensor and tied the lead of the 2N3904 (coming out through the hole) to the tap on the potentiometer. Note that I cut the trace just below the hole which originally tied the over-current circuit to the nShutdown pin, which I grounded with a large solder blob just to the right of the hole.

For the final test, I installed the unit back in the 914 EV, turned on the ignition and turned on all the accessories. The DCDC seemed to handle the current reasonably well without heating up much. The real acid test will be to drive around at night with the headlights on and see if the DC-DC fails again. Things look promising so far. I'm a bit miffed that CCPower could have solved this issue themselves with a cheap (69cents from Radio Shack, cheaper in bulk) transistor. I'll be driving around after dark this evening and will keep y'all posted.

I Blew it Again! Learning About Soft-Start...

2007-09-08T21:59:00.001-07:00

After studying the oscilloscope waveforms, I believed that the current sense circuit was way too spikey. This is the "amp adjust" potentiometer output in the C400 schematic. I found that the inductive spikes were shutting off the DC-DC converter through the nShutdown pin on the SG3525A and causing craziness in the gate-drive pulse. Soooo, I picked a reasonable (.01uF) capacitor to filter out the current sense waveform and remove the inductive spikes.

Here's the .01uF capacitor soldered to the board across the "Amp Adjust" potentiometer output.

If you compare the voltage spikes in this scope view to the one in the previous post, the inductive spikes are still there, but not as prominent.

Here's the same view under a 7 amp load. Note the gate drive pulse at the bottom of the screen has widened out to 8usec. The inductive spikes are much smaller and don't trigger the nShutdown circuit.

At this point when I apply just over a 14 amp load, the current sense circuit pulses are high enough to trigger the nShutdown pin on the SG3525A. When this happens, I note that the output voltage drops because we are in current limiting mode (good). However, the FET gate pulse is all over the place and the DC-DC converter whines loudly. This is important to remember after you read the next section...

I turned down the current limit to 14 amps and re-installed it in the 914 EV. After powering up the car, the unit didn't blow. I turned on the headlights and the system kept working. I then turned on the fog lights, tail lights, turn-signals and reverse lights. The DC-DC started whining loudly as stated in the previous paragraph. I thought this was good because I figured it was in current limiting mode. However, after a few seconds, the system went silent and, as I feared, I had blown the FETs again.... (sigh).

After taking a break, I read some textbooks and analyzed the SG3525A circuit diagrams once more. I'm going to take a wild guess that this is what happened (for all you advanced EE geeks):

When the unit goes into overcurrent mode, it pulses the nShutdown signal which immediately turns off the output gate drive. This causes the output voltage to lower and the inverting input from the opto-coupler to fall, increasing the duty cycle of the gate-drive. What I find on the oscilloscope in over-current mode is that the PWM output to the gate drive jumps wildly from 0-100%. This clearly puts the primary coils of the transformer into saturation mode and stresses the drive FETs.

After much textbook research, I believe that the overcurrent circuit should quickly bleed voltage off the soft-start capacitor without quickly turning off the output PWM pulse to prevent the PWM pulse from going above a certain limit. What we want is to have the gate-drive pulse change its state smoothly instead of wildly jumping all over the place.

A good example of how this is done is shown at:

http://www.edaboard.com/ftopic153496.html

If you look at the schematic halfway down the page, the overcurrent sensing circuit draws down the soft-start capacitor and doesn't drive the nShutdown pin as in the CCPower schematic.

I'm going to try and alter this circuit with a pull-down transistor and put it into overcurrent to see if the gate-drive oscillates or simply maxes out.

This is one hell of a learning experience, especially for a digital engineer like myself.

Goodnight.

Debugging the DC-DC waveforms

2007-09-08T16:37:00.000-07:00

I spent most of Friday trying to figure out just what was blowing the DC-DC converter.

Here's my full testbench setup. On the upper left, I have a 156V DC power supply. On the lower-left sits a 12V battery to act as an accessory battery. The 30Mhz $400 oscilloscope sits ready. The opened up DC-DC converter is front and center. I have the oscope covered with cardboard to shield out excess light so I can take pictures of waveforms. I actually used the aluminum case for the DC-DC converter as a camera stand so that I could turn off the flash which causes too much glare on the oscope screen.

Here's a close-up view of the 156V power supply. In essence, I took five 31.2 volt power supplies from HP inkjet printers and hooked them up in series. I broke off the grounding pin of all the power cords except the bottom supply so that the output stage could float and allow the series connection. These supplies put out 2.5 amps, so this ought to provide 375 watts of power if I need it for testing.

Okay, here's the first scope trace. I removed the blown FETs and simply measured Vgs at the missing part location. Dimensions are 5us/div and 5V/div. It looks like we have a period of 30us and the power supply for the SG3525A is 12 volts. Without the FETs in place the controller drives both FETs in push-pull configuration at their full duty cycle. There's actually a dead time of about 0.6us between the high states on the gate-drive pulses.

I've just soldered in two IRFP460 FETs (still with no load on the output) and here's what the gate-drive looks like. The pulse from the SG3525A is on the bottom and the actual Vgs voltage at the FET is the top waveform. The IRFP460 part has a larger gate capacitance than the original IRFP350 parts, so the charge and discharge slope doesn't look so great. Perhaps I could reduce the resistance of the gate-drive resistors to help with this. The FETs are still cold with no load. With the FET in place, the drive pulse shortens to 0.9us. Dimensions are 0.5us/div and 5V/div.

Here's where things get interesting. I'm now measuring the drain-source voltage on one of the FETs (Vds) with no output load. Dimensions are 20us/div and 50V/div. Without any load, the voltage swings on the FETs are twice the input voltage (about 312 volts) plus any ringing from inductor kick-back! One of the disadvantages of the push-pull architecture is that the driving transistors need to handle twice the input voltage.

The far left of the screen shows one FET turning off and letting the voltage oscillate. The two high spikes near the right edge of the screen show the voltage across the first FET as the second FET turns on. There's even over-voltage from the inductive ringing. If the input voltage goes up to 170V with charging and regenerative braking, the FETs need to handle at least 340 volts plus the ringing voltage, which is typically even higher... (yikes!)

I've added the 12V accessory battery as an output load and let things settle. This picture shows the gate drive (Vgs) of one FET (bottom left) and the resulting source-drain voltage (Vds) on the opposite FET. Time dimension is 5us/div. Note that the pulses going to the FET gates are 15us apart, causing the snap to a low voltage three divisions into the display. The Vgs pulse is still about 1.2 usec wide.

Here's the same image as above, but with a 7 amp load. The SG3525A is now pulsing the FETs much more often to handle the load. The gate-drive pulses are now 8us wide and the drain-source voltages are clearly jumping from zero volts to 156 volts to 312 volts.

The circuit controlling this pulse width is the opto-coupler feedback going into the inverting input on the SG3525A. As the load increases, the main output voltage tends to drop, telling the 741 op-amp to turn off the 4N25 opto-coupler. With the opto-coupler off, the inverting input for the error amplifier in the SG3525A falls and increases the pulse width. (See schematic in previous blog posting)

What boggles me about this picture is that this DC-DC converter was supposed to put out 400 watts. That's about 28 amps. Just pulling 7 amps causes the gate drive pulse width to increase to 8us which is over half of the available 15us time that they can be on. If I add another 7 amp load, the gate pulse width extends out to its full width of 15us and then the waveforms go a bit nuts. It seems to me that if we run out of controllable pulse width at 14 amps, then the controller has no way of providing anywhere near 28 amps. Hmm....

Another circuit I analyzed was the amperage control circuit. This circuit captures current going through the isolation transformer and converts it to voltage pulses. If these pulses get too high then the SG3525A controller should turn off the FET gate drives to prevent them from overheating. The top waveform in the above picture shows the voltage across the "Amps Adjust" potentiometer with just the 12V accessory battery load. Note that the primary signal shows nice rolling pulses; however, there are sharp spikes at every gate drive transition. These rolling pulses are supposed to control the nShutdown pin on the SG3525A controller. The unfortunate thing is that the actual voltage triggering the nShutdown pin are the voltage spikes. I believe the dimensions are 0.5V/div for the top waveform and 5us/div timebase.

Here's that same picture with a 7 amp load. The bottom waveform shows the FET gate drive pulses widening out to 8us and the voltage on the "amps adjust" pot show a much higher voltage (with much higher spikes too). I really need to get rid of those spikes.

I'm unsure of where to go next. It's clear to me that the 312 volts across the FETs along with the inductive kick-back spikes are running very near to the operating point of the FETs. At high current pulls, the inductive spikes are only going to get worse and tend to blow the FETs. I'm also concerned that a 7 amp load consumes just over 50% of the available pulse width modulation range for the gate-drive pulses, so we just can't supply more than about 13 amps without maxing out.

My first step is to try and reduce the inductive spiking. The only circuit provided for that is the C7/R16 capacitor/resistor pair between the FET drain posts. I found a great article on how to pick these values on the Maxim website here:

http://www.maxim-ic.com/appnotes.cfm/an_pk/3835

I also might add an RC filter to the "amps adjust" circuit to filter out the high-voltage spikes so that the nShutdown input gets a more accurate voltage.

I still haven't heard back from CCpower about this, but I'll give them a few more days. As you might imagine, I'm rather frustrated that I have to debug someone else's design. I'm not sure this component was meant for this application.

Initial CCPower Schematic

2007-09-05T08:05:00.000-07:00

In my efforts to debug the failures of the DC-DC converter, I tried to capture a schematic of the board. I didn't have time to create a component for the SG3525A controller, but all the pin numbers are listed. I replaced the IRFP350 FETs with IRFP460 FETs which have a higher isolation voltage and larger drive current; however, they also have about twice the gate capacitance, which I didn't think of.

Any suggestions for what could blow the FETs up would be helpful (please leave in comments section).

You can get a larger image by clicking on the thumbnail above.
Links to the various parts are:

IRFP350
IRFP460
SG3525A

The failing conditions are when the 12V accessories are drawing a lot of current (25 amps) and the output voltage has sagged down to 12V (DC-DC tries to put out 13.9V).

I'm guessing that as the voltage sags, the output (pin 6) of the 741 op-amp goes low and turns off the LED in the opto-coupler. With the opto-coupler off, the voltage goes low on pin1 of the SG3525A (inverting input to error amp) and increases the pulse widths going to the drive FETs. If the pulse widths are too long, they cause the FETs to stay on too long and saturate the inductors, which causes a high-current spike of +144V that blows the FETs.

Supposedly, the current sense loop voltage that is adjusted by the R8 potentiometer should send a positive pulse into pin10 of the controller to shut down the FETs, but this may not be happening quickly enough.

Initially, I cringed because there were no kick-back diodes in the circuit, but I think that C7 and R16 (2 watt resistor) send any kick-back currents into the opposite inductor when the FETs let go.

Any ideas? Thanks for your input.

Cheers,
Tim

Taking a Break

2007-08-30T22:06:00.000-07:00

These last few days have packed with non-EV stuff, but I did take the DC-DC controller into the lab to see what was going on. First of all, there are no kick-back diodes on the inductors inside the converter. This kinda scares me since pulling on an inductor with a FET and then letting it go tends to create really high voltages (> 600V etc...).

I hacked together a 160V DC power source by simply tapping off the bulk capacitor inside one of our power supplies. It fired up the DC-DC converter, but the whole thing was moving up and down at 60 Hz, it was darn near impossible to look at things with an oscilloscope.

Next week I plan on taking five 32-volt isolated supplies (2.5 amp) and hooking them up in series to form a 2.5 amp 160V supply with a non oscillating ground so that I can probe all the internal nodes better. Fortunately, we use these supplies all the time for our inkjet printers, so there's piles of them around.

In the meantime, I'm e-mailing with Mike at Electro Auto to try and figure this out before he sends me another DC-DC converter to blow. I'm going to try and get by with charging up the 12V battery at the same time as the 144V pack and just running them both down at the same time. During the daytime, this isn't bad since the headlights consume most of the power. I hooked up a .01 ohm resistor to measure current draw from the battery and found that I can pull 30 amps with everything on, but this is rather atypical. Supposedly, the battery can supply 30 amps for an hour, so I should be okay with a 30 minute commute. This is still frustrating.

Remember, it's just a process...

PakTrakr is Online! DC-DC blown again...

2007-08-26T21:42:00.001-07:00

I spent most of yesterday and a few hours today wiring up the PakTrakr system. It's a bit of a pain to disconnect the most negative lead before attaching the display, but that's minor nuisance. It seems to measure pack voltage well; however, the voltage measurement on each battery seems to be slightly inaccurate. The Zivan charger is balancing the batteries well and each of them is within an 8.48V-8.50V range (20mv difference is pretty good!).

I chose to mount the display on the central console as shown above. It doesn't have a backlight but is easy to read during the daytime and the placement makes the buttons easy to access.

I had to greatly extend one of the PakTrakr remote module cables so that the rear battery pack could talk to the remote modules in the front of the car. That involved cutting one of the 3-wire cables on one remote module and splicing in an 8-foot extension of additional 3-wire cable. I added heat-shrink tubing to make the splices clean so they could be pulled through the right-hand heater duct under the passenger-side door.

The system seems to work fine. Having a backlight would be nice, but not necessary. My biggest gripe is that double sided tape seems to have a big problem sticking to the back of the PakTrakr modules, even though they tell you to use it to mount the modules.

On a downer note, the CCPower DC-DC converter blew again (fuse was vaporized and FETs shorted out). I actually caught the system in a working condition just before driving home and found out that it had blown when I got home. The only difference was that the DC-DC converter was under a heavy load on the drive home because the headlights were on.

Based on the circuit inside the DC-DC converter, I suspect that there is a significant amount of current (required from the headlights) going through 144V side. When the FET opens, the current rushing through the inductor causes a high voltage spike (300-400V is not unheard of) that gets added to the +144V side and just wipes out the 500V FET. I'll have to double check to see if the inductive kick-back diode is properly functioning. The CCPower website only has the input voltage of their DC-DC converters listed as 80 volts so, although these are designed for EVs, the underlying design may not be able to handle the higher voltage, especially with spikes from regenerative braking.

In the meantime, I'm using a 12V charger to charge the accessory battery as well. Maybe I can integrate that into the overall charging circuitry when I plug in the car.

Talking with Mike at ElectroAuto

2007-08-25T13:05:00.001-07:00

I just got off the phone with Mike at Electro Automotive. We chatted about the blown CCPower DC-DC converter and the engine vibrations. Since I fixed the DC-DC converter, we agreed that I would try to find out which conditions would cause it to blow again, if it does. It seems that Mike is more of a mechanical person than an electronics person. He graciously faxed me a circuit to generate a tach pulse from an ADC8" or 9" motor, but he didn't really understand the circuit. Unfortunately, the circuit relies on the fan inside the motor interrupting an optical emitter-receiver pair which doesn't exist on the AC24 motor in my vehicle.

He also agreed to provide a new motor to flywheel coupler if I still had engine vibrations. Mike commented that it was probably not the transmission, but probably had to do with the flywheel/clutch assembly. I'll have to do some more experiments to figure that out when I get the time and energy to take the motor/tranny back out.

I also said that I would look into the peak amps that the system draws if I could find a suitable ammeter. I still don't have the shunt or the console gauges since ElectroAuto is still waiting to see what peak amperage it has to deal with. When I told Mike that I easily pulled > 150 amps during acceleration, he seemed a bit surprised.

Apparently I'm the only person with an operational AC kit currently, although several other people are hot on the trail to finishing theirs. Mike doesn't have an AC kit 914 back at the ranch.

Regarding the 8V golf-cart batteries, Mike also mentioned that they tended to either last 3-4 years or die right away (infant mortality). I hope I don't have a batch that demonstrates the "infant mortality" behavior...

Okay, I'm going on a bike trip next weekend and need to get biking gear, so the 914 will have to wait for a bit.

Fixing the DC-DC Converter

2007-08-24T22:28:00.000-07:00

I cringe at the thought of having to send anything back to Electro Automotive for replacement or repair, so I took a chance and dissected the DC-DC converter to see if I could fix it. The company that makes the DC-DC converter is CC-Power in the UK, so I don't think sending it back to them would be timely either.

Here's the DC-DC converter taken out of its black aluminum case. The clips that held the FETs and diodes in place were a bit annoying to take off, but I finally got them with some needle-nose pliers. The circuit is basically a heavy-duty buck step-down converter with a bunch of inductors. The output stage is a transformer in push-pull configuration with two diodes to handle both sides of the coil. An opto-isolator takes the output and transfers a reference current back to the primary stage to regulate the voltage.

To the best of my knowledge, the inductor sitting on the table is directly in line with the +144V and is used to limit inrush current. The transformer coil on the left does the same to the +13.6V side, basically just a series inductor. The transformer coil on the right is the isolation transformer with +144V and +13.6V windings to transfer the current. The two TO-220 case parts on the top are the diodes to rectify the current coming out of the output side of the isolation transformer. The two filter capacitors on the left smooth out the +144V and +13.6V. The two FETs on the bottom edge of the board pulse current into the input stage of the isolation transformer. The rest of the circuit is just integrated circuits to drive the FETs and monitor the output voltage.

Here is one of the two IRFP350 FETs that clearly blew up. If you look closely at the burn marks, there is even a hole blown in the part package. Both FETs had blown and were shorted out. Since the FETs are rated at 16 amps and the fast-acting input fuse was rated at 5 amps, I suspect the FETs sustained damage from a high-voltage spike that went past their 400 volt rating.

The explosion from the FET shown above was so powerful, it even blew a hole in the steel clip that held it against the heat sink. (I'm glad I wasn't around when it blew!).

I went on a quest this evening back to the labstock at my work and found some IRFP460 FETs in the same package. They are rated for 500V and 18 amps instead of 16, so I thought they would be a good replacement. Heck, I might as well at least try since I probably voided the warranty when I opened up the case.

Here is the DC-DC circuit board with the new FET leads sticking out the bottom edge for resoldering. The middle lead is tied to the back of the FET, making it a good heatsink and difficult to solder without creating a cold solder joint.

Okay, I did a quick assembly without heatsink clips and attached the 144 volt pack to the input with a new 5-amp fast-acting fuse, and voila, the DC-DC started working again. So, I went back and did a full re-assembly with putting the heatsink clips back on and attaching the 12V accessory battery. The DC-DC seems to be working fine again. It creates a small whine unlike the blown unit before and it puts out 13.9 volts to charge up the accessory battery.

I have no idea why or how the DC-DC converter blew, but I suspect it will probably happen again given that I've only really driven the car for four days. As long as I check the fuse I'll know if it went bad or not. The red LED on top of the DC-DC converter lights up with a 12V accessory battery attached, even though the unit is blown, so I can't rely on that. Based on an idea from Ross Cunniff, I could rig up an op-amp comparator circuit that lights up the the generator warning light whenever the 12V accessory battery is below a certain threshold. That way I know the DC-DC converter isn't working and I can check it out. The other idea is just to add a green LED to the 144V inside the converter just past the fuse so that I can see at a glance if the fuse has blown. There are many other projects that I'd like to do first though, so for the meantime, I'll just periodically check the DC-DC fuse.

Good Night.

Getting the EV Back to the Shop and Fixing Electrical Stuff

2007-08-24T22:07:00.000-07:00

Just before noon, I drove with the ICE vehicle over to the 914, charged the accessory battery with jumper cables for about 20 minutes, then quickly drove the 914 back home to the garage for repairs. Since the stranded EV was only 2 1/2 miles away, I walked back to the ICE car and drove it home too. Since the DC-DC converter was blown and I didn't want to deal with it, I focussed on some other electrical problems I'd been having.

The first issue is that I get major voltage drops when I turn on 12V accessories like the headlights and the turn-signals. Because the accessory battery is now in the front of the car and tied directly into the fuse block, the actual current path to the ignition switch (and the lights) goes from the fuse block all the way back to the original 12V battery position (see step VI.F.7 in the kit instructions), through a bolt connecting the large red wires, and then back to the ignition switch. The accessories were causing the voltage to drop at the main accessory battery, but I noticed an additional 1.5 volt drop from the wire resistance going to the back of the car and front again.

To fix this, I found the two thickest red wires under the fuse block going to the back of the car. I cut them both near the firewall and used an ohm-meter to figure out which one went to the ignition switch. I then added a yellow 1/4" quick-connect connector on the end of the ignition switch input routed it along the wiring loom and plugged it directly into the fuseblock where the other thick red wire came from. This eliminated the 1.5 volt drop from the long wiring and the 12V system is much happier.

The second issue I wanted to address was the lack of a heater/cooler fan blowing out the ducts. To get at the contacts which turn on the blower motor and fan light, you simply remove the ashtray in the center of the dash all the way (press down on the center clip).

Here's a look into the ashtray hole down onto the electrical contacts (just behind the black/blue and brown wires near the center of the picture). These didn't seem to work at all, or only intermittently. I globbed a bunch of dielectric grease onto the contacts and used a long flathead screwdriver to scrape away all the corrosion and carbon buildup. There was a tremendous amount of dust and other dirt in there that I cleaned out with an old worn-out toothbrush.

After all that scraping (the dielectric grease acted somewhat as a solvent too), the fan operated at all three speeds and the fan light lights when the fan goes on. The next step for the climate control system will be to add hair dryers to heat the cabin. Unless I come up with a better idea, I'll probably tie the hair-dryers directly to the 144 volt system through relays controlled by the rear-defroster pull-knob.

DC/DC converter blown

2007-08-24T10:17:00.000-07:00

Well, I ran out to Radio Shack this morning and got some more 5 amp fuses for the DC/DC converter. After plugging a fast-blow fuse in, powering up the car blows the fuse. I tried a slow-blow fuse and that went too. I then disconnected the 12V battery to see if that was causing a problem and it still blew a fuse.

What's sort of interesting is that these glass fuses didn't just melt and break, they really vaporized and completely coated the inside of the fuse glass with metal bits. It looks like there's a pretty serious short in the DC/DC converter.

The car is still stranded at Krista's place. I brought over jumper cables and tried to charge the battery with my ICE vehicle. The voltage drop across the 300amp jumper cables was 0.8 volts so I'm guessing the 12V battery was mostly dead. Since this is my day off, I might take a risk, charge it up some more and try to crawl home for repairs. The distance is only 2.2 miles and the main 144V pack is happy up around 151V. Grrr...

EV Toolbox

2007-08-24T07:07:00.000-07:00

Before the accessory battery discharge yesterday, I wrote down a list of things to keep in the EV in case there was a breakdown out on the road. I came up with the following items. Any comments for additions or modifications would be welcome.

Emergency Equipment

cable cutters
small fire extinguisher (for electrical fires)

Repair Tools

Haynes manual for electrical diagrams
digital multimeter
wire crimper and extra pink,blue,yellow quick-connect crimps
two battery wrenches wrapped in electrical tape
electrical tape
extra cable lugs and hammer-based crimp tool
medium hammer
LED headlamp
extra fuses (DC-DC converter anyone?)
pre-made 24" battery cable with lugs (from NAPA)
#2 philips/standard screwdrivers
pliers
small utility knife to cut insulation
small 12V SLA battery to bootstrap the system if 12V battery dies

Again, what would you add/subtract/modify in this kit?

Next up: fixing the stranded car, looking at the PakTrakr and getting the heater fan to work.

12V Auxilliary Battery Dies!

2007-08-23T22:01:00.000-07:00

While cruising over to my girlfriend's house this evening, the whole system just shut down on the road. That was a rather scary experience. The hazard signals started flickering and nothing would turn on. After pulling over and checking the voltage on everything, the pack was nicely up at 150V but the accessory battery was down to 10.5 volts. With the key on, the DC-DC converter light was on; however, when I checked the DC-DC fuse, it was blown. Apparently, I've been running down my accessory battery for awhile now.

The car is stranded for the moment until I try replacing the fuse to see what the issue is. Worst case, I can charge the accessory battery with a long extension cord just to get the car home.

Ugh, goodnight.

Commuting...

2007-08-23T09:06:00.000-07:00

Despite the issues with the car, I've decided to start commuting 15 miles each way to work to see how the car does. By not revving the motor above 5000RPM, I can minimize the vibration problem.

The batteries are starting to break in. I'm getting slightly more power on the freeway now and starting from a dead stop is acceptable. I've taken the 914 up to 70mph. It doesn't have the pep that the original 2.0 liter engine had, but I still haven't really cranked up the AC controller and done a parameter analysis.

The car wobbles at 60mph with a low-frequency side-to-side shaking, so I took it into Les Schwab this morning and they found one of the back tires to be significantly out of balance. I'll take it back up to 60mph on the trip home.

In general, I'm pleased with the freeway performance. Although, if I put the car under heavy acceleration for a long period of time, the batteries "brown-out" down to 128V or so and the controller cuts back the power significantly as the voltage drops. Letting up on the accelerator allows the battery voltage to come back up and power comes back. I could adjust the parameter in the AC controller to set the voltage cutoff lower, but I fear damaging the batteries.

I looked at installing the PakTrakr battery monitoring system last weekend; however, the wiring distance between the front and back of the car is longer than the provided cables. Ken Hall (makes PakTrakr) said that I could extend the cables as far as necessary, so I grabbed some 4-wire cable and will be extending things soon.

I've given several people at work rides to show them the technology and everyone has been very supportive.

Next up: More commuting and checking out PakTrakr

NEDRA Pictures

2007-08-17T22:14:00.000-07:00

Going to NEDRA at Portland International Raceway was my first major excursion in the 914 since both the flywheel was balanced and the clutch was properly adjusted. The car handled very well and cruised on the freeway without much problem. I did get up to 65 but kept my speed mostly at 50 to not pull too much current while breaking in the batteries.

Here's the wait in line for the ticket office at Portland International Raceway. I felt proud to not have to waste gas while idling in line.

I spent most of the time answering questions about the 914 so I didn't take too many pictures or see too many races. Maybe next year I'll try it out.

Here's a more serious electric drag racer. As you can see, the original engine compartment up front is fairly barren. The Zilla2K controller sits in the bottom.

Here's looking in the rear window where all the A123 batteries are. There are probably more pounds of high-current Anderson connectors than batteries.

Here's the "purist" control cockpit.

While not a racer, this entry was rather interesting since its electric motor didn't power the wheels...

but it powered a huge fan on the back of the car.

Here's Miles' antique vehicle that he brings to most of the OEVA monthly gatherings.

Miles uses Hawker Genesis batteries to power the antique vehicle. Much lower maintenance than the originals!

This is a Honda Civic Delsol conversion done by Chris Brune who helped me understand how to drive my electric car better using lower gears and higher RPMs.

That's all the photos I took. There were many more vehicles and many fun EV drag races. Just as I left, one EV drag racer had just spun out into the wall. Exciting times indeed.

Grommets Anyone?

2007-08-17T17:07:00.000-07:00

In my frustration to take care of the vibrating of the motor/tranny, I unbolted the motor from the front engine mount and raised it up with a jack. The clearance above the motor is tight so you can't raise it too much. After revving up the motor, it still resonates at 5000 RPM which leads me to believe that there's an issue with the motor to transmission coupling. If the transmission shaft is slightly off center then the whole thing could wobble.

To try and fix this, I put two 1" rubber grommets around the bolts between the front engine mount and the black motor mount. After re-tightening all the bolts and revving up the engine, it still resonates, but significantly less. I can probably deal with this for awhile. We'll see...

Off to NEDRA...

Fixing the Flywheel - Still Vibrations!

2007-08-17T14:31:00.001-07:00

This has been one heck of a week. I took the flywheel into an automotive machine shop to balance along with the attached clutch assembly. In the meantime, I tried to figure out if the real problem was the motor to flywheel adapter from Electro Automotive.

I borrowed a precision dial gauge from a coworker and measured the wobble on the motor adapter. Initially, it had a full 7 mils (thousandths of an inch) of difference in depth. After trying to alter the tilt by tightening down the two screws on the high side first, I got that down to 4 mils.

Turning the outer hub of the adapter had absolutely no effect, so it must be a problem with the inner mating cone. I filed down the motor shaft key and that had no effect. Only using a semi-round file on the inside of the cone (that touches the motor shaft) under where the key rests started to move things out of tilt. After much filing on the inside of the cone, I got the face of the adapter to tilt less than 1 mil, so I was happy with that.

In order to adjust things and remeasure, I purchased a 7-ton gear puller (with posi-lock) from Sears for $70. It worked remarkably well at popping off the adapter from the motor shaft with minimal effort and no possibility of damage to the threads on the inner cone of the adapter. I had to pull this thing off about twenty times to finally get the adapter face flat, so the $70 was well worth the effort.

One person suggested I send the adapter back to ElectroAuto since the cone was flawed. Quite frankly, they aren't responding right now and with NEDRA happening tonight, I was just too impatient to wait (possibly for months) to get a new adapter...

Here's the modified flywheel back from the shop. The backside was slimmed down to reduce weight and the starter motor teeth were removed to save weight as well. The markings in the middle are my own when figuring out the high and low spots.

With the adapter face now within 1 mil of depth, I put the flywheel on in several positions and it's face now moves in and out only 4 mils. That's acceptable for now.

KIDS: DON'T TRY THIS AT HOME. I attached the motor with flywheel up to the AC controller to see if it would vibrate when I got it up to 5000 RPM. By tuning back the torque and maximum RPM in the parameters of the controller, I safely spun up the wheel to 5500 RPM with nowobbling and very minimal vibration. In the picture above, the flash of the camera makes the wheel look still, but the clutch alignment pins on the outer edge are a bit of a blur.

With things balanced, I finally mated the motor/flywheel/clutch assembly back into the transmission. Notice the flywheel has no teeth and has just enough diameter to hold the clutch pressure plate. Also notice the two drill divots in the side of the flywheel that the shop drilled to balance it.

Here's the assembly on the furniture dolly. When I removed this from the car, there was only one 2x4 under the front motor mount. I realized that there is enough clearance to use two 2x4s and it puts the whole assembly closer to the underside of the car when I jack the motor/tranny into place.

Here it is again, ready for insertion. I taped up the shielding on the 3-phase AC cable to keep the end from fraying.

With the assembly rolled under the car, I simply put a jack under each end of the front motor mount and jacked it into place so I could insert the motor mount bolts again. Since the whole thing has to tilt while I attach the rear transmission mounts, I left the nuts on the front motor mount bolts somewhat loose.

Here's jacking up the rear end of the transmission so I can bolt the transmission mounts back into place. Don't forget to tighten the front motor mount bolts when you're done!

After re-attaching all the other wires and mechanical cables, I fired up the AC motor again and spun it up to 5500 RPM. What!!??? The car still vibrates!!

I think I've been barking up the wrong tree for the past few weeks. Since the electric motor is directly bolted to the front motor mount without any rubber engine mounts, I highly suspect that the 914 chassis has a resonant frequency around 5000 Hz and the light vibrations from the electric motor are stimulating it.

I'm taking the car to show off at NEDRA tonight anyway. I never get up to 5000 RPM if I stay in 2nd gear in neighborhoods and 3rd gear on the freeway.

Next up: Finding rubber mounts to add to the system to see if that helps things out. Grrrrr.

Taking a Day off to see the EV Show

2007-08-12T08:48:00.001-07:00

I took the day off to walk around Portland to the farmers market and EV awareness day with Krista. There were probably twenty electric vehicles at EV awareness day. Here are just a few of the more notable ones.

The electrically augmented bicycle. This was originally just a human powered vehicle made in Belgium, but the owner added an electric motor to power the rear third wheel to get up the hills in Portland (of which there aren't many in Belgium).

Here are some cool looking Neighborhood Electric Vehicles (NEVs). They run on 48 volts and the company sells them as a kit for about $3500. With batteries and additional items, the final cost is around $5000. Not bad for something that has a top speed of 50mph.

Here is my (tongue in cheek) arch nemesis John Benson. He built the DC version of the Electro Automotive kit awhile back and challenged me to a drag duel at Nedra next week. Based on my experience with acceleration, he'd toast my AC 914 in the drag race, but I'd win in an endurance race.

Next Up: Tweaking the adapter hub and trying out the PakTrakr

Balancing the Flywheel/Clutch

2007-08-10T16:04:00.000-07:00

Okay, since I take Fridays off, this gives me a chance to take the flywheel into a machine shop for balancing. I took the flywheel and clutch pressure plate to Portland Engine Rebuilders. They basically said that they couldn't balance the flywheel because they couldn't attach their balancing machine to the small center hole. Many thanks to Alan at A&P Specialties (Audi and Porsche repair) for lending me a 1.7Liter 914 crankshaft so I could provide something for P.E.R. to balance.

Here's the crankshaft from a 1.7L 914 that Alan graciously let me borrow.

Here's the crankshaft with the connecting-rods removed.

Here is the crankshaft with the bolted on flywheel. I delivered this to Portland Engine Rebuilders to 1) remove the outer 1/2" of the flywheel (basically the starter motor teeth) and 2) balance the whole assembly along with the clutch pressure plate so everything is stable. Ted, the owner of P.E.R., was very kind and explained the whole process as well as making some suggestions for how to lighten the flywheel without losing strength up at 6000 RPM. Machining the flywheel and balancing should take about a week.

Back at home, I purchased new 10-24 x 1" allen head bolts to re-attach the adapter hub to the AC motor shaft. Since the face of the adapter seemed shallow on the side where the motor key sat, I tightened up the bolts on the opposite side first to try and bring that side deeper to flatten out the face.

Here I'm using a piece of plastic (yes that's a filler plate for the 5.25 inch drive on a computer case) to determine if the face of the adapter is flat. By holding the piece of plastic in the right place and bracing it against non-moving parts, I can turn the motor shaft by hand and hear where the face scrapes the plastic. This second time around I think the adapter is flatter, but still slightly off. I smeared some red loctite on the deeper surface to act as a liquid shim to try and flatten it out more. We'll see what happens when the flywheel comes back.

Next Up: Taking a break for a few days and possibly installing the PakTrakr battery monitor.

PakTrakr Arrives and Adapter Misaligned

2007-08-09T20:45:00.001-07:00

Well, this day definitely had its ups and downs. The PakTrakr battery monitoring system I was expecting early next week actually showed up today.

Here's the PakTrakr still in all its bags. The main display and one battery monitor unit is in the upper-left bag. Three extension battery monitors are in the other three bags. The serial cable in the lower left can hold 2MBytes of log data before dumping it down to a laptop. Each monitor can handle six batteries. My vehicle has 18 batteries, but I chose to purchase a total of four monitors due to the distribution of batteries in the car. This means more cost, but far less wiring and installation hassle.

Okay, on to the gritty part. I dropped a bunch of leftover parts at camp914 today and picked up the 12-point CV joint bolt removal tool from Craig. After removing the CV joints, I rolled the motor/tranny out from under the car and wiggled off the transmission.

After close inspection of the flywheel, it looks like it wobbles about 30 mils (thousands of an inch) which could be causing the problem. I unbolted the flywheel and used a piece of plastic rubbing against the hand-spun adapter hub to see if it was unbalanced. Unfortunately, the adapter hub from ElectroAuto was tilted to one side about 6 mils. This may not seem like much, but this tiny distance gets amplified through the radius of the flywheel up to 30 mils. Just to make sure the flywheel wasn't tilted on its own, I put the flywheel back on rotated approximately 180 degrees. The tilt was still 30 mils and it followed the tilt in the adapter hub, not the flywheel rotation, so now I know it's a problem with the adapter or the AC motor shaft.

After removing the adapter plate and large heavy spacer ring around the adapter hub, I found that one edge of the wedge inside the hub was slightly more depressed than the opposite edge. This is a bit of a relief because it points away from the shaft on the AC motor being bent. I had to use a 7-ton gear puller from Sears (model 104 Posi-Lock) to pull off the adapter hub.

The instructions say that you can remove the adapter by backing out the small allen head bolts and rapping them with a brass hammer. After slightly backing out the bolts, only a few threads were still in the adapter hub, so hitting them with a hammer only broke off the threads. That's why I had to resort to the gear puller. I'm quite surprised that ElectroAuto suggests using allenhead bolts for the hub that are only 3/4" long. The threads are much deeper. Since I damaged the shallow threads, I'm going to mount this again using 1" bolts instead.

Make sure you do NOT put Red Loctite on these small allen-head bolts like it says in the instructions. The flywheel prevents them from coming out and the loctite simply glues the wedge inside the adapter hub tight so you cannot remove it! (my bad)

Here's the mess after I took everything apart.

The object of my frustration: the adapter hub. The left edge of the inner wedge seemed to pull in 6 mils further than the right edge. I'm going to screw in the bolts on the right edge (near the slot) first to see if I can compensate for this tilt.

Next Up: Having the flywheel balanced and lightened at a machine shop.

Biting the Bullet - Book 2

2007-08-08T21:11:00.000-07:00

In my eagerness to balance the flywheel, I unhooked all the mechanical and electrical cables from the motor/transmission assembly and lowered it onto a furniture dolly. Note that I still need to borrow the CV joint bolt remover from Craig at Camp914, so the assembly is just sitting on the floor right now. I'll try to describe the process in a little detail since Joe posted a comment a few hours ago asking for more pictures.

First up was removing all the mechanical cables. The speedo cable came off easily. I put the end in a plastic bag to avoid dirt and grit. The clutch cable (which I had just adjusted) took a bit more time and I saved the nuts and stop-wedge in a plastic bag. I had to thread this through the engine mount so it wouldn't interfere with the motor coming down. The shift linkage came off much more easily since I had greased it up and the throttle cable came off too since it was wrapped around the motor.

For the electrical stuff, I first popped off the reverse light wiring and tie-wrapped it out of the way. Next came the grounding strap (don't forget that!). The hardest wiring was the speed sensor wiring from the motor.

The picture above shows the speed sensor box opened up. I had to carefully unscrew the wires on the bottom and feed them through the small entry hole and then through the two-inch hole in the wall between the engine compartment and the rear luggage compartment. I also tie-wrapped these in a plastic bag to protect the ends.

After disconnecting a copper bar on the battery pack and pulling off the plug on the Zivan charger (caused sparks before), I carefully unbolted the three thick cables coming from the AC controller. After feeding this thick cable down through the hole in the luggage compartment floor, the assembly was free to lower.

I didn't want to go through the hassle of lowering the whole car to lower the motor/tranny, so I took a different approach. First, I put the rear of the car up on six-ton jackstands. Then, I removed the rear tires to give myself more space to work.

Since I have two floor jacks, I put one under each end of the front motor mounting bar. With the jacks pressed against the bar, I could remove the mounting bar bolts and slide a furniture dolly under the motor. I had to slide the dolly forward quite a bit and put a 2x4 across the end so that the other end of the dolly didn't crush the clutch cable bracket when it was lowered. I then slowly lowered each of the floor jacks on each side little-by-little until the motor mount sat on the 2x4. I had to remove the white cups from the floor jacks so that the raising surface was low enough to get the motor mount arms on to the furniture dolly.

With no more weight on the floor jacks, I moved one around to the rear of the car under the transmission and put slight upward pressure on the tranny. With this slight upward pressure, I could remove the bolts from the rear transmission mounts without much trouble. I then added two more 2x4s to the furniture dolly and lowered the floor jack until the bottom of the transmission just forward of the clutch pulley bracket dropped onto the 2x4s.

Here's the lowered motor/transmission. Note the single 2x4 on the front of the dolly holding up the motor mount. The rear 2x4s are just under the transmission. I still have to get a CV joint bolt remover tomorrow from camp914 to take off the CV joints. Note the ground strap dangling off the top rear of the transmission. After I remove the CV joints, I'll jack up the car higher on the jackstands and roll the motor/transmission out the back.

Note the blue reverse switch wire in the upper left of the picture, the grey speed sensor cable off to the left and the thick black AC controller cable on the left. (Click on the picture for a larger version)

I performed all the above work in about two hours. This is far faster than the 1 week it took me to lower the engine/transmission in the first place. Things go much faster when you do them the second time. I'm a little surprised at how much I've learned in this process.

Next up: finding a CV joint bolt tool, removing the flywheel and balancing the whole thing.

Swallowing my Ego

2007-08-07T13:28:00.000-07:00

Over the past few days, I've gone through the four stages of acceptance regarding the rather noisy vibration that the car undergoes when I rev the motor above 3500 RPM.

Denial: "My new electric car is wonderful and it doesn't really rattle above 3500 RPM."

Anger: "Why the hell does my car vibrate and rattle about 3500 RPM???!! It's not supposed to do that! Can't the Porsche folks make a good flywheel? Can't ElectroAuto make a good adapter coupling?"

Negotiation: "This would be sooooo cool to show everyone at EV awareness day and to show my friends. Maybe I can just drive around and keep the RPMs under 3000 for a week or two until I figure out the best path forward.

Acceptance: "Okay, I remember when I installed the flywheel that it didn't go on completely straight (only a few hundredths of an inch off...) and this could really screw up the electric motor bearings and the transmission. I better bite the bullet now and deal with this so I can get on the road more quickly."

I'd like to thank Mark the mechanical guy I met through an OEVA member and my co-worker Steve (retired mechanical engineer and AutoCross enthusiast) for beating some sense into me about this. I'm an electrical guy, after all. (Can't we just reboot it?)

Next up: A character building experience involving removal of the transmission and repositioning the flywheel, if it's possible.

Shifting Fixed and Charger Outlet Installed

2007-08-06T21:32:00.001-07:00

Things just keep getting better and better with this car. I did some experiments this morning with operating the transmission and found that my clutch wasn't fully disengaging. After adjusting the clutch to fully release this evening, the car shifts MUCH better and I don't grind gears anymore! What a relief!

I also took this evening to finish up the wiring for the external charging outlet on the front fender of the car. This means I don't have to open the hood to charge the car.

The instructions call for cutting a 1 7/8" hole. Sears only had a 1 3/4" hole saw, so I cut the smaller hole and then used a grinding wheel to grind off the plastic threads on the outlet insert down to 1 3/4". I believe the fit to be much more solid.

I also didn't have a 9/16" drill for the power cord hole, so I used a 1/2" drill and greased up the cable with silicone spray so that it would easily slip through the slightly smaller grommet. The silicone spray also helped get the cord through the weather seal on the backside of the outlet insert.

After rummaging around in my leftover parts from ElectroAuto, I also found a temperature sensor for the Zivan NG3 charger, plugged it in and tie wrapped it to the inside of the front battery box.

I just sent an e-mail to a local guy who has helped a few folks out with mechanical issues on their electric vehicles. I'm hoping he will be able to help me with my flywheel balancing issue. Craig from camp914 suggested I take the flywheel/clutch assembly to a shop for balancing too.

In preparation for EV awareness day in Portland this coming weekend, I plan to label all the components so I can better explain things to interested people.

Several folks have asked about 0-60 time, range and top-speed specifications for this car. I haven't really pushed it yet, and probably don't intend to, but I'll capture more data over the next few weeks.

Test Drive to Work

2007-08-05T11:25:00.000-07:00

Since traffic is really light on Sunday morning, I drove to work (15 miles away) and back to see how the 914 would handle.

Shifting was a real pain on city streets since the electric motor changes RPM very quickly during acceleration or regeneration. The RPM stays constant when I "coast" unlike a gasoline engine which tends to slowly drift back to "idle." This makes synchronization of the gears rather difficult.

As expected, power was rather lacking on the freeway. It took me 30 seconds to get up to 60 mph. After analyzing the AC controller logs, it turns out that I only took the motor up to 3000 RPM and it is spec'ed at 12000, so maybe I'll try a lower gear next time to get more torque at the wheels. I just have to get used to the concept of driving at higher RPM, since I got better gas mileage by keeping the RPMs low on my old car (which is 19 years newer than the 914 :).

If my ammeter from West Marine is correct, then just cruising takes about 50 amps and every time I accelerate even slightly, the current goes up over 200 amps. I'm not sure how much current these golf cart batteries are designed for. The battery voltage sunk from 152 volts at rest down to 132 volts after awhile during heavy acceleration. The controller cuts current to the motor if the voltage drops, so I definitely lost power on the uphill exit ramp off the freeway. I think people experience cognitive dissonance when they see a little red Porsche sports car being the slowest car on the road.

I'll be happy to e-mail anyone logs from the AC controller if you'd like to parse the data with Excel to see how the controller behaves. If I can capture a screen, I might even post a picture here.

My First EV Video

2007-08-03T14:31:00.000-07:00

My friend Pete dropped by for lunch today with his video camera and we captured a four-minute video of the electric car in action as well as a description of the various parts. This is rather unrefined, so enjoy...

Hacking the Regen System and Fixing Acceleration

2007-08-01T19:20:00.000-07:00

Well, today was a good day. I got word back from Azure Dynamics after they analyzed my acceleration logs and they pointed me to the EE2NoAccelBat variable. Mine was set to 136 volts. It turns out that if the voltage coming from my batteries fell into the 136 to 149 volt range (EE2NoAccelBat + EE2AccelRamp = 149), then the controller would linearly limit the power going into the motor down to zero when the voltage reached 136.

With a 144V nominal pack, at moderate current draws, I was getting major power loss. Azure recommended setting EE2NoAccelBat to 127, so that this "scale-back" range was a more reasonable 127-140V. This made a HUGE difference in acceleration performance as my battery voltage rarely drops below about 138, even drawing 120 amps.

In other words: READ THE FRIGGIN MANUAL (RTFM) and understand all the graphs

The car was still rather difficult to drive with the regenerative braking happening when I released the accelerator. In a comment to a prior blog entry, Paul J suggested that I try using the brake light signal from the brake pedal to activate the regenerative system. With my driving frustration, this seemed like a good idea.

This change actually reverses the function of the regen relay. In the original kit instructions, the regen relay turns on the brake lights when the AC controller is in regen mode. With the PaulJ brake mod (I might just call it that...), I remove the regen relay and use a similar (normally closed) relay to activate the regen function when the brake lights come on.

Again, this involves purchasing a normally closed relay so that when the brake lights come on, it opens up and lets the regen circuit activate on the AC controller.

This worked like a charm! The car is soooo much easier to drive because it behaves much more like a gas powered vehicle. That is, you push the acclerator to go and press the brake to stop. The relatively weak brakes are augmented strongly by the regen function of the AC controller, so the brakes are actually much more responsive, despite the heavier car. I recommend this alteration to anyone using this kit!

A final task was to mount the ammeter that I had been using for experimental purposes. Until I get the cool looking dials from ElectroAuto, I just shoved the ammeter in the place where the engine temperature gauge was. I had to break off two of the long mounting pins so it would fit in the hole, but this will work until I get something better.

On another really bright note, I contacted the facilities manager at HP about having a plug-in at work for charging my vehicle. I had contacted him last October and he said he would get around to it. Much to my delight, the work actually happened without him telling me and there's a plug-in (with an Electric Vehicles Only sign!!!!) just outside my building!!! Yay!!! I'm sure this is all part of HP's plan to look more "green," but I'm still ecstatic that I don't have to walk halfway around the site just to plug in my vehicle. Here's a picture:

I've pushed really hard these past few days to get the car going. The Oregon Electric Vehicle meeting is tomorrow and EV awareness day is August 11th. Also, the NEDRA races are on August 17-18, so if I'm really lucky, I'll try to get the car to these events. The test drive with the improved acceleration and "PaulJ Brake Mod" makes the car feel much more road worthy.

Off for a quick test drive and then to collapse. Cheers!

Hacked Serial Cable Details and Bad Relay

2007-07-31T19:07:00.001-07:00

A few people asked me about how I hacked together a serial port since AC kit people will need this in order to configure the controller correctly.

I basically took three 16 gauge wires (smaller would be fine) and soldered on crimp sockets at the end of each one. I also added heatshrink tubing so that adjacent signals wouldn't short out. The picture above shows the three wires plugged into the top three pins on the 8-pin connector on the controller. Yellow is Txd(controller to PC), blue is Rxd (PC to controller) and brown is ground.

Here's a view of the heat-shrunk ends with the sockets crimped and soldered on.

To connect to the PC, I got a female DB9 connector with solder cups. The solder cups were designed to handle 20 or 22 gauge wire, so I had to trim down the 16 gauge wire to fit into the cups. Txd to the PC goes on pin 2, Rxd goes on pin 3 and ground goes on pin 5. All connections were soldered to solder cups in the top row.

From there, I just used a long male-female 9-pin serial cable to connect to the male DB9 on the back of the PC. Again, if you use HyperTerm, the settings are 19200baud,N,8,1, no handshake.

Remember the flakey relay I found yesterday. Here it is, removed from the car. One set of contacts was highly resistive. I replaced this relay with the charger interlock relay from the front relay mounting board to get the car working. Afterwards, I pried off the clear plastic cover (off to the left in the picture) and used an extremely thin file to break through any corrosion on the bad contacts. The contacts on the common swing arm were actually slightly bent so only a tiny corner of the common contact touched the normally-open contact when the relay activated.

I'll keep this relay around as a spare since I replaced the front charger interlock relay with a normally-closed SPST relay from the auto parts store.

The car seems to start much more reliably now.

Next up: getting more performance and acceleration..... maybe.

Power calculations

2007-07-30T22:21:00.001-07:00

After looking at the specs on the ElectroAuto website, I'm thinking that a maximum input power rating of 50000 watts is really too much. Here are the ElectroAuto specs:

AC24 Aircooled Motor
Length	Diameter	Weight	Controller	Efficiency
15.55"	9.45"	83.6 lbs.	DMOC445	83%

Specifications @ 156 V Input
	Ft.Lbs.	Amps	RPM	HP	KW
Peak/Maximum	54.57	280 rms	12,000	57.66 @ 4,500 rpm	43
Continuous	22.12	180 rms	12,000	18.77	14

55 Ft-Lbs peak is 75 Newton-meters. The controller is programmed for 100 Newton-Meters.
I'm guessing I should probably back off the peak wattage to 43,000 as listed in the chart unless I want to severely harm the life of the motor.

The original Porsche 914 2.0L engine had about 90 peak HP so this is definitely less. It looksl like I'll have to shift more often to balance the motor torque with my desired speed. The regenerative braking makes shifting really hard, so I'll probably have to utilize the regen-disable switch more often.

I also think I figured out what the high-pitched squeal/scraping noise was. The controller puts out a 10Khz PWM signal to modulate the three AC waveforms. I hear this squeal during acceleration and regeneration, but if I let the motor spin freely by putting the accelerator in the middle, there's no squealing. The squealing never changes frequency either. I didn't expect the motor to be that noisy... Live and learn.

The last big issue I probably have with the car is that the flywheel is probably out of balance. When the motor hits about 4500 rpm, the whole car starts vibrating rather nastily. This means I'll probably have to take the transmission off again and have the flywheel balanced, or re-turned by someone before general use. Urg.

I sure hope people don't have to put up with my mistakes on their own 914 AC conversions!

Good night.

Debugging, Debugging, Debugging...

2007-07-30T21:32:00.000-07:00

Okay, things don't seem to be working too well. We have three issues:

1. The controller simply cuts out at high acceleration (bad)

2. Many times the controller doesn't even start up at all

3. There's very little power from the system, I can't go much above 30mph

After sending error logs to Azure Dynamics, they came back with the following:

"Vehicles with improper or substandard grounding and shielding sometimes exhibit nuisance errors flagged as EE3LastError = 16. Once every measure for improving the grounding and shielding has been taken, it is OK to disable this error if the problem persists. This can be achieved by setting EE2DisableChargedError = 1."

It's very true that I forgot to add the grounding strap to the DMOC controller that ElectroAuto provided. So I added the strap with anti-corrosion compound and made sure to scrape the metal clean on the bottom side of the bolt on the chassis to make a good contact.

Here's the grounding strap provided by ElectroAuto bolted in. Unfortunately, this didn't help much with the problem. I found that turning down IdsMax from 400 amps to 380 amps did help the problem. Also turning down the MaxAccelTorque from 100Nm to 85nM helped too.
Given that the car has not a lot of power to start with, I set the EE2DisableChargedError to 1 to get past the issue with all the original settings.

Okay, next up is the problem with things just not starting at all. I logged more variables and saw that the ISR2CarDirection status register was zero when the car failed to start and 1 when the car worked. This pointed to the "Forward" signal on pin 29 of the DMOC controller not getting properly grounded.

I double checked the connections on the neutral-start relay in the engine compartment and everything looked fine. I even looked at the contacts to make sure they were in the right place. It turns out when I wiggled the wires on pins 6 and 9 ("ground" and "forward"), the CarDirection bit randomly toggled between zero and one.

To debug further, I took two other wires with crimps and measured the resistance between the two contacts on the relay. The resistance was often infinite or around 5-10 ohms. This really caught me off guard since I put a lot of faith in relays, especially Potter and Brumsfeld's. I'm probably going to take the relay out tomorrow and see if I can open it up to see if something is damaged. I would have suspected my own wiring, but not the relay... (sigh).

I have to show off the car tomorrow to a bunch of friends and I can tap the neutral start relay now to get things running.

That leaves the problem of not having a lot of power. I could get up to about 30mph on residential streets in 2nd gear, but not much past that. I'm guessing I'll have to shift up and take the torque hit.

The power thing was really confusing to me because the current measurements as listed in the controller ccShell diagnostic tool said 400 amps. I wasn't seeing a huge voltage drop, so I didn't believe the controller, at least from a DC-current point of view. Sooooooo, I ran out to my favorite overpriced EV hardware store: WestMarine. They had a 150 amp shunt-based ammeter there for $90 (ouch).

This is the 150 amp ammeter shunt. It's in the place of the most-positive battery terminal in the fuel compartment. The shunt is remarkably small compared to the pictures I've seen of the ElectroAuto shunt. Also, placing it in the fuel compartment makes it much closer to the dashboard, so there will be less signal loss over the shorter wires to the dash.

Here's the ammeter dial itself (the camera flash whites out the background). It seemed to work quite well. At full acceleration, it pegs at 80 amps almost all the time. This is a lot less than the 400 that the ccShell window states. I suspect that the 400 amps is some internal calculated number of instantaneous current going through the stator instead of an actually measured value.

After messing around with several parameters, the only ones that affected the current draw were the EE?MinPowerAccel, EE?NormPowerAccel and EE?MaxPowerAccel. Since I haven't hooked up the dashboard switches and dials, the controller was operating in maximum power mode, so tweaking EE?MaxPowerAccel would limit the current to 40amps or raise it up to 95. I took a chance and bumped up the MaxPower from 31000 to 50000. I'll have to double check the power spec of the AC24 motor before using this too much.

Okay, enough for today. The kit requires the 12V accessory battery to run the exhaust fans while the car charges overnight, so I altered the circuit to use an external 12V laptop supply instead so I wouldn't drain the accessory battery.

Here's my temporary charging setup. The Zivan charger is in low-current mode (12 amps) and I have the 12V laptop supply also plugged in to run the exhaust fans.

Tomorrow: taking a break
Wednesday: dissecting the neutral-start relay and figure out why it doesn't work.
(I can replace it with the front charger interlock relay in the short term...)

Hoods Installed

2007-07-29T15:19:00.001-07:00

Well, we're getting closer. My friend Rick and his friend Amy came over today to help install the front and rear lids. I was rather relieved when both lids closed without any interference. I installed the engine compartment cover this morning and realized that the rain gutter would have to be completely removed to not interfere with the rear battery box. With the rain gutter gone, perhaps it wasn't such a good idea to keep the two drain funnels and tubes in place...

I did a few more laps around the block this morning and played around with the parameters in the AC controller via the serial port. When I have the serial port plugged in, the controller fires up and things seem to work. If I power down and remove the serial port, nothing comes on. I'm trying to debug this further. Hopefully Azure Dynamics can get back to me by Monday to see if I've adjusted anything wrong.

I find that if I back off the maximum torque (EE?MaxAccelTorque), I can get get the car running without stalling, but I give up some power. I can also limit the stalls if I back off on the IsMax parameter from 400 amps to 380 amps. For some reason I find it very difficult to imagine that I'm pulling 400 amps from the batteries. The voltage doesn't seem to dip that low and I don't get much acceleration. I would think the car would have more pep pulling 400 amps.

With the serial port yanked, I had to push the car back into the garage for more analysis. This is all part of the learning process and I look forward to learning more...

Pictures from Randy

2007-07-28T16:52:00.000-07:00

One of my fellow 914 AC kit EV'ers is Randy Pollock. He's been extremely helpful in my understanding of how this kit works. About three weeks ago, he sent me a few pictures on his own 914 AC EV project that uses the Electro Automotive kit. Here are his pictures and text (verbatim) from his e-mail: (Thanks Randy!)
---------------------------------------------------------------------------------
Hi all,

Attached are some pictures from my rear trunk now that I have the
Avcon receptacle wired to the Manzanita Micro charger. The junction
box next to the receptacle has two green idicator lights. If only
one is light, then 110V is present - 220V lights both. I have both
the Avcon charging station with will put out 220V and an extra cable
that I've added a 110V plug to the other end. So far I've only
tested the 110V cable and it starts up the charger as expected.

There is also a close up of the cooling fan I added. The small
component to the [left] (not completely wired yet) is a 105F on/90 F
off thermostat switch. When the trunk starts getting hot from either
the charger or the AC motor controller, the fan will kick on. It is
a very powerful side exhaust fan that should be able to turn the air
in the rear trunk over ever 30 seconds. It kicked up some dust under
the car when I tried it out. Note that the thermostat is mounted on
nylon screws so that it is sensing the air temperature, not the sheet
metal temperature.

The last picture shows the four 2" holes I cut behind my PORSCHE
reflector on the back of the car. You can't see anything from
outside, but since the reflector stands almost 1/2" off the sheet
metal, you can get reasonable air flow.

I do need to cut the mouse hole for the Avcon cable. It will be cut
out of the trunk lid. I have a spoiler that provides enough material
to make it work.

Just thought you would like to see.

- Randy

Closing the Boxes and Fixing the Suspension

2007-07-28T16:21:00.001-07:00

I took a few minutes (just a few) to go out with friends to celebrate.

Here's my girlfriend Krista enjoying a very brief ride to the bottom of the driveway. The front tires still bottom out when I turn the wheels too hard, so I'm holding off major test drives.

Here are my friends (Krista, Ruth and Rick) just before we went walking to get some gelato on this fine day.

Okay, back to work after a good night's sleep. My first concern was the front of the car bottoming out. Fortunately one of the steps in the manual is to adjust the front torsion bars.
The Haynes manual covers this reasonably well.

The center of the torsion bars were supposed to be about 8.5 inches off the ground. Initially they were 5. No wonder I'm having issues.

Turning the torsion adjustment bolt was far too difficult with all the weight on the tires, so I jacked up each side of the front of the car and tightened both bolts until the center of the torsion bar was about 8 inches above the ground (after letting the front end back down).

Here's a closeup of the torsion adjustment nut. Its the nut on the very bottom that turns the vertical bolt that you can see the threads on. This picture was taken tooking toward the front of the car from just behind the front-right tire.

Next step was to finish the battery box covers. Here are the covers and hold-down bars in place for the front two battery boxes. For the rear bar on the front battery box (under the charger tray), the holes for the bolts line up exactly with the vertical walls of the cups on the bottom side of the cover (at least for the bar I was given). I had to re-drill these holes about an inch further out to the side to not interfere with the internal hold-down ups.

The hold-down cups on the bottom of the middle battery box interfered with the tabs on the speed-caps for the batteries. I took my cable cutters to one of the two tabs on each speed cap to fix this issue.

For the rear box, the lid was too big to fit between the passenger wall and the rear luggage wall, so I had to use vise grips to bend the rear luggage wall back about 1/8" so the lid would drop in.
I also had to knock off one of the hold-down cups on the bottom side of the lid because it interfered with the fusible link that I modified to fit around the speed-caps. With the other hold-down cups in place and the copper bars holding the batteries together, I didn't feel that this would be a huge safety issue.

The black wire going up over the roof of the car is the serial cable going to my laptop in the passenger seat.

After a few more test drives around the block, I've noticed that the controller tends to cut out suddenly under a heavy torque load. I can get the controller to die just by putting the car in reverse and flooring the pedal to leave the garage, so I don't think this is a reasonable limit. I'll be researching all the parameters again to see if there are some "unreasonable" limits I can increase without harming the system.

Next Up: Putting all the lids back on!

First Driving Test!

2007-07-27T16:04:00.000-07:00

Well, I carefully fixed the black grounding wire to the motor encoders and the system seems to work fine now. I got the AC motor to rev up quite quickly in neutral. Both forward and reverse movements are fairly smooth.

For yucks, I drove the car around the block. It has very slow acceleration, probably due to all the battery weight. I drove it in second gear. Third gear seems to not want to go in, at least while the car is stopped. The regen braking seems to work fine. The front end is rather heavy with batteries and the tires scrape something in the wheel wells when I back out of the driveway down the small cement slope on the curb.

There is much to do, but I at least know it runs and that I'm probably not going to race it at Nedra...

Off to celebrate with a brownie and a very much needed nap. Yay!

Aha! A Broken Wire!

2007-07-27T14:51:00.001-07:00

I collected a bunch of controller data over the serial port on my laptop and sent that off to Azure Dynamics for analysis. After looking at the data, the ISR2Hertz variable (i.e. RPM) was pegged at zero. This led me to believe that there was something wrong with the motor encoders.

I opened up the motor speed monitor box and probed around. All the encoder signals were up at 4.9 volts and the black ground wire was also up around 4.83 volts. After examining things some more, I found a broken wire on the AMP connector going into the controller.

Here is the black broken ground wire. I'm not great at fixing these things, but I'll definitely give it a shot. Worst case, I can get one of the technicians back at HP to help me fix it.

I let Azure Dynamics know so they don't spend too much time on the analysis.

Next Up: Try, try again...

Wow, This is Really Fast! NOT!

2007-07-27T10:30:00.000-07:00

Just a quick update. I removed the jack-stands, cleaned out the garage and fired up the 914EV. It responds properly to the accelerator, but at full throttle, the car goes about six inches a second both forward and reverse. Looks like I've got more DMOC parameters to adjust. Fun, Fun.

Things still to do:
- Fix the right window
- Install the 12V transformer for the charger interlock and fans
- Add the battery box covers
- Put all hoods and lids back on the car
- Add the gauges and control switches to the dashboard

Onward!

9:12am July 27, 2007 - It's Alive!

2007-07-27T09:30:00.001-07:00

This morning, I hacked together a serial cable to talk with the ccShell program provided by Azure Dynamics to communicate with the controller. You need to contact Azure Dynamics directly to get the .ccs file that works with ccShell; it's not available on their FTP site.

Here's the hacked up serial cable attached to the laptop. After setting up Hyperterm for 19,200 baud N,8,1,no handshake, I was able to turn the keyswitch and get a boot screen and binary data dumping out the serial port.

Here's a closeup screenshot of the "Edit" window in ccShell. While I haven't tried out many features, it looks like the tool is quite powerful and able to monitor and log a vast array of variables in the controller. The variables listed in the documentation don't quite match up to the variables shown in ccShell, but I could infer their meaning.

Okay, why the heck isn't my motor turning...

After looking at the wires attached to the controller, it seems that DMOC pin 30 isn't hooked up at all. Hmm, that's the drive enable signal! Why wouldn't we hook that up? It turns out that you can override this digital input by setting the EEXNoIgnSwitch variable in ccShell to "1". I had to do a reset on the controller after downloading the value to the controller's EEPROM.

Okay, after setting EEXNoIgnSwitch to 1, I lightly pressed on the accelerator and heard noises coming from the transmission! Yay, the motor spins! The car is up on jack-stands, so I put it in reverse (backup lights come on, good) and press the accelerator again. What??!!, the wheels turn in the FORWARD direction. Rats. Okay, back to the documentation. There's another variable named EE2ShaftDirection which allows the user to reverse the direction of the motor. After setting this variable, the wheels turn in the right direction! Yay! If you click on the ccShell screen above, you can see the EE2ShaftDirection variable set to -1.

One vaguely unsetting noise is that when the motor turns, I hear periodic light scraping sounds. I suspect that the flywheel might be rubbing against something. I really don't want to take apart the transmission again! I'm debating right now if I can let this slide for a bit (turn the radio up louder?). I'm excited but concerned that something might blow up at this point...

Next up: removing the jack stands and securing the battery box covers...

ADDENDUM (July 28th): In addition to setting the ShaftDirection variable to -1, you'll also have to set the EncoderDirection variable (some name like that) to -1, otherwise the motor will report negative ISR2Hertz values (bad!)

Close, but no Cigar...

2007-07-26T23:14:00.000-07:00

I didnt' get a chance to do much tonight, but I did hook up the final fusible links in the battery system. Before hooking up the links, I jacked up the rear of the car and put in on jackstands just in case something started happening with the motor. I also put the transmission in neutral.

Here's the front fusible link in place. No sparks yet!

Here's the rear fusible link. Initially this failed the "spark" test. I touched the link to the two battery terminals and got a medium sized spark. I vaguely remembered getting a similar spark when plugging in the Zivan charger to the bank of batteries on the floor. Sooooo, I unplugged the Zivan charger from the system and tried touching the fusible link again. Voila! No spark!

Here is the voltage measured at the AC controller. Looks like we have about 8.4 volts per battery. Good.

Of course the next step was to get out the fire extinguisher and turn the key on. Guess what? Nothing happened. It looks like the controller is getting 12 volts, but there must be something holding back the controller from spinning the motor. Darn safety interlocks!

It's late so tomorrow I'll be running off to buy parts to build a serial port connector to the AC controller. My laptop is over three years old, so I ordered a new battery last week and it showed up today.

Hopefully, firing up the AC controller serial console will help me find out what's holding the controller back from turning the motor. I thought I heard something like a faint whine happen in the motor area for about a third of a second when I first turned on the key, but that could just be in my head.

Oh, one other thing that I think I figured out. A long time ago, when I hooked up the potbox, I thought that ElectroAuto provided the wrong instructions for hooking up the potbox microswitch. It turns out their instructions seem to be okay. The safety interlock inside the AC controller prevents the user from moving until the throttle is fully open and the "forward" signal is disabled. The neutral start interlock relay will only stay open if the user turns on the key with the relay open. After pressing the accelerator, this relay closes and puts the AC controller in "forward" mode.

Let's see what come up on the serial console tomorrow...

Wiring and Rewiring - Getting Close!

2007-07-25T23:09:00.001-07:00

Ugh, I'm dehydrated, exhausted and mad at this inanimate object. I must love doing this conversion... (There's a fine line between a hobby and insanity)

Tonight was spent attaching all the copper bars to the battery terminals. I received an updated wiring diagram for the AC kit from ElectroAuto, and, much to my disappointment, many of the connections went between the battery caps. All the US Battery models tend to have "speed caps", so routing copper bars between caps on a single battery is impossible without breaking the speed caps. So, to use the bars provided, I bent them every which way I could to fit around the speed caps.

Here's the fusible link in the front battery box. Notice the large bulge in the copper bar on the right half.

Here's the same fusible link viewed from above. The bulge on the right half is needed to accommodate the opening of the speed-cap. I also had to hacksaw off about 3/32" of the bottom edge of the bar because it sits on the "wrong" side of the battery terminals and needs some clearance for the terminal heads.

Here's the long copper bar used in the rear battery box. To prevent routing it between the battery caps as shown in the ElectroAuto diagram, I used 2" stainless bolts to extend it beyond the speed caps on the top. I didn't like doing this because the stainless bolts would have a higher resistance than the copper and a much smaller surface area. Stay tuned for a better solution.

Here's the fusible link for the rear battery box. This is bent identically to the one in the front box and has the same curve on one side to accommodate the opening of the speed-caps.

Since the AC kit comes with 2 gauge wire instead of 2/0 gauge wire, I was able to use a short piece of welding cable with two lugs and route _under_ the speed caps to connect the terminals that formerly required the long copper bar.

The updated low-voltage wiring diagram shows different connections in the front compartment. I rewired the modification to the fuse block so that all the 12V accessories were connected to the key-switch directly again. I found the black wire going to the rear engine compartment and drove that wire individually from the interlock relay output in the front trunk. Hint: remember the two smaller wires you cut off the large black wire in step ???, the larger of these two smaller wires goes directly back to the rear engine compartment and was used in the original instructions to turn on the AC controller.

In short, we still route two black wires up to the front luggage compartment so that we can activate the keyswitch relay. The only difference is that in one case, the interlock relay turns off most of the keyswitched 12V system and this modification only switches off the AC controller when the charger interlock relay engages.

Electro Auto made the mistake of sending me two 12V-coil relays for the front luggage compartment. One of these was supposed to have a 120V coil so that plugging in the car would shut off the AC controller and turn on the fans. One of the problems with their updated wiring diagram is that when the charger interlock relay is on, all the venting fans are driven by the 12V accessory battery and nothing is keep that battery recharged. If the battery runs out, the fans stop, which is bad.

In short, I'm going to get a small 12V transformer that will drive both the interlock relay and drive the fans when the car is plugged in. This saves wear and tear on the accessory battery and let's me use the 12V-coil relay as the interlock relay.

Whew! After much playing around with the anti-corrosion goop, I finally have the front battery box all wired up (except the fusible link) and ready to fire up the system.

Note the thick welding cable coming into the box from the rear of the car. The smaller welding cable goes to the middle battery box and is small enough to fit under the speed caps to prevent clearance problems when closing the front-box lid.

Here's the middle battery box with the copper bars and welding cable installed.

And finally, the rear battery box with all copper bars and cables installed except the fusible link. It's much safer to wire things in when theres a break in the serial battery connections.

Next up: Getting some sleep and testing out the high-voltage system by measuring voltages and installing the fusible links. Not long now before we can try to spin the motor!

Hauling Lead and Confusing Connections

2007-07-23T22:19:00.001-07:00

Tonight was an evening of heavy lifting. These high-capacity 8-volt golf-cart batteries are 70 pounds apiece. I'll definitely take some ibuprofen before tomorrow.

Here are the batteries in the front box.

The fuel compartment box...

And the rear box.

I pre-laid out these batteries on the floor to guestimate what the connections between the terminals were. I couldn't find a good solution with the copper bars supplied by ElectroAuto, so I just took my best guess and gave it a shot. I've got an e-mail into ElectroAuto for some connection diagrams, but haven't received the files yet.

Here is the battery strap designed for these kind of batteries. I got this battery strap at a Yamaha golf cart dealer. The advantage is that it attaches easily to the battery at the loading loops on the edge. The downside is that you can't use the strap for "edge" batteries. Note how close the loading loops are to the edges of the battery on either side of the filler caps. I was able to load most of the batteries with this strap away from an edge and then slide the battery into position.

For the edge batteries, the other battery strap I had contained two large loops which I could hook around some bolts threaded through the battery terminals. I didn't like to use this because I felt it put undue stress on the terminals.

A modification of the prior strap is basically what is suggested in the DC kit instructions. I used bolts, washers and nuts to create my own special battery strap which could quickly slide into a set of battery terminals and lift it. Again, I tried to use this strap on as few batteries as possible because I was concerned about applying too much tilt force to the "L" terminals.

Okay, onto the copper battery interconnects. It turns out that the only copper interconnect that fit right out of the kit bag was the completely flat bar with two holes. All other bars had to be re-bent in a vise to fit properly around the terminals.

Here's a picture of the front battery box with the short interconnects temporarily in place. I forgot to get 5/16" stainless steel flat washers to properly connect these copper bars (whoops, back to the hardware store). Note the large interconnect missing from the two battery terminals in the center of the box. These are for the front box fusible link, shown later.

Temporary links for middle box.

Temporary links for the rear box. Note the very far link in a reverse "S" shape. I found a funny shaped link in the kit, but could simply not get it to fit anywhere in the system. Out of impatience, I bent the link to fit the terminal spacing around the far corner of the battery box.

Also note the missing fusible link near the center of the pack and the long vertical link not really connecting the lower right two batteries. I might have to add long stainless bolts because this piece of copper just isn't long enough to get to the terminals and still fit around the filler caps.

Here are the supplied fusible links. I'm rather confused by them because they have 1/4" holes instead of 5/16" holes like the rest of the copper bars in the system. The bars also don't seem to fit anywhere in the whole battery system nicely, so something is awry with where these go. I'm guessing I'll end of bending them to fit the remaining terminals in the battery boxes, but I'd sure like to know what the designers intended.

We're getting closer. Time to go back to the hardware store for stainless washers and bolts to finish installing the interconnect. Goodnight.

Busy Day - Time to get your WooGah On

2007-07-20T20:31:00.000-07:00

Whoosh! Despite being exhausted from yesterday, I got up early this morning and just cranked through a bunch of EV stuff on my day off.

Here is the board that the charger tray mounts to. There's a clear piece of acrylic providing a small gap so that the board can hinge forward and upwards without any edge interference. I'm holding this in place with clamps so I can drill the hinge holes without the board moving around.

After drilling the hinge holes, I went ahead and drilled the eight holes to hold the charger tray and filled them with bolts. I mounted the tray as far to the right as possible to open up space on the board to the left for one of my favorite pieces of equipment on the vehicle: the WooGah horn. Note: The AC kit instructions don't say what to install the charger tray with. I used one inch 1/4-2o bolts with washers and nylock nuts on the back.

Here's the mounting board on my kitchen table (er, workbench) with the washers and nuts installed on the back to hold the charger tray on. I've also bolted on the two hinges at the top edge as well.

Here is the bottom of the charger tray. I had to choose very shallow countersunk 1/4-20 bolts so that they wouldn't protrude beyond the black rubber feet on the top two corners. Alas, the rear two nuts were still too thick and I had to countersink the bottom and install the flathead bolts from below to get enough clearance.

Here's the Zivan NG3 charger sitting nicely in its tray with the AC power cord off to the right.

And here's the whole assembly in the vehicle. I still haven't bolted the hinges to the rear wall because I forgot to get enough 10-32 flathead bolts from the hardware store. The instructions call for 1-inch bolts, but I found that 3/4" worked just fine since the hinges are so thin.

Moving onto the middle battery box: Here are the fan wires coming off the exhaust fan. The brown wire tied to the black fan terminal goes to a stud that is hidden and not easy to see under the heater hose to the right.

Here's the front half of the rear battery box going in.

When installing the threaded hold-down rods, I found that there was so much gunk in the battery rack thread nut that I had to apply a rather large amount of torque just to make the rod go in the support nut. To get enough torque, I put two nuts on the top end of the rod and tightened them together so that I could put a wrench on the top nut and screw the rod in.

Here is the wiring for the rear box fan. I later changed the brown wire to point off to the left so there would be no interference with the tie-down bar. The instructions call for a red wire coming from the engine loom. I didn't find this and added my own red wire for the fan that goes back to the upper terminal block to the brown fan-power supply wire. Possibly a glitch in the instructions.

Here's the other half of the rear battery box installed. I was amazed at how tight a fit it is. The box didn't fit quite right (see far right corner poking up above the red wall), so I had to grind down some edges like I did a few days ago for the front battery box. Again, the fit is really tight. There's not more than one millimeter of space between the box edges and the front and rear walls. I feel rather fortunate to get this installed rather well. Hopefully the weight of the batteries will help it settle.

Here is the exhaust hose for the middle battery box. I think there's a problem with the instructions. They call for using 1/2" long bolts to hold down the exhaust port on the left, but due to the curvature of the wheel-well, this really requires more like 1-inch bolts for the nut to have enough threads to grab.

After running to the hardware store, I finally installed the hinges from the charger board on to the rear luggage compartment wall. Here is the whole setup installed.

Just to test out all the battery box fans, I shorted the positive terminal of the front fan to the battery positive terminal. All three battery box fans spun up without too much noise, so all the connections seem well.

Since I've finished all the work on the firewall, I installed the seats again to free up more room in the tiny garage.

Here's my favorite WooGah horn mounted to the left of the charger. I don't know if the connections to the battery are better, but it's really loud! Get your WooGah on!

With the majority of the wiring done, I added several tie wraps to the cables under the rear luggage compartment to keep things from moving around.

I also re-installed the rear tires since most of the undercarriage wiring is done.

Last but not least, I took off all the temporary charging cables from the batteries so they are free to be installed in the vehicle.

I still don't have any instrument gauges from ElecroAutomotive, but I can put together temporary switches to get things going.

Next up: installing the batteries in the boxes!

We are Green for 12V Electrical!

2007-07-19T23:23:00.000-07:00

Whew! I spent the evening debugging the small sparking issue I ran into yesterday. The behavior was interesting in that the keyswitch relay closed for about a second and then released. In the process, the DC-DC converter turned on (indicated by red LED) and then slowly decayed to the off state.

It turns out that this behavior is explained by the rather large capacitive load between 12V and ground provided by the capacitors in the system, probably from the CD player and the VDO clock. To further explain, one side of the keyswitch relay is tied to the ignition switched 12V rail, now floating to the same potential as the unswitched 12V rail(i.e. 12V). Since the positive terminal of the auxiliary battery is tied to the unswitched 12V rail, the negative terminal of the battery is at zero volts.

When we attach the black wire in step XXV.R of the DC instructions, it drives the keyswitch relay coil instantaneously with 12 volts, energizing the coil. Current flows through the coil to charge down the capacitive load on the ignition switched 12V rail until it is 12V below the unswitched rail (down to zero volts). After the coil charges down the capacitive load, there isn't enough voltage to keep the coil energized and it turns off after a second. I suppose this is rather confusing, so send me a comment or e-mail if you'd like further details.

Here are the negative high-voltage connections. The 10 gauge black wire comes from the charger and the smaller yellow wire drives the voltmeter in the cockpit and drives the DC-DC converter.

Here is the wiring from the 9-wire bundle that was threaded through the driver-side heater duct. Most of the wires attach to the upper terminal block to interface with the DMOC AC controller. The dangling white and green wire go to the ammeter shunt and the dangling black wire I think is not used in the AC kit.

The moment of truth! After attaching all the wires and chassis ground in the front luggage rack, the green oil light comes on (and the annoying seat-belt buzzer) when I insert the key and turn it to the "on" position. I was also able to turn on the CD player and it started playing the CD I had left in there from when the car had a gasoline (yuck!) engine. Yay! This marks a rather huge milestone in getting most of the wiring hooked up correctly.

WARNING: Step XXVI in the DC instructions doesn't really apply to the AC system as many of the connections are much different. You can definitely test the green oil light, but don't short out any terminals as mentioned in step XXVI.G!!

Next step in the instructions is to add weatherstripping to the front battery box edges. The weatherstripping. The weatherstripping comes with two strips attached side-by-side. I found it most useful to measure all the horizontal edges and cut a piece to get both top and bottom horizontal edge before doing the same with all the vertical edges. Using this method, I was able to most efficiently utilize the dual-strip weather stripping.

Here's the battery box top sitting in place. We need this here to install the charger mount next.

We also need to add the flexible plastic pipe for the front battery box vent fan. Trust the instructions when they say that installing the upper hose clamp is easier.

Next up: Installing the mount for the charger.

Must.......Get.......Sleeeeeeeeeep.......

Forcing a Fit and Letting Sparks Fly

2007-07-18T22:30:00.001-07:00

Well, after yesterday's letdown with the front battery box not fitting into the steel frame, I loaded up on caffeine and pulled out the grinding wheel.

Here is the front battery box not fitting into the front rack. If you click on the picture for a larger view, you can see the front-side edge not in the rack. I first tried a hand file, but made much more progress with a paint removal wheel attached to a drill.

Here we are, slowly grinding away 1/32" of plastic at a time to hopefully not reduce the structural integrity of the front battery box.

Yay! The front box now fits into the rack (albeit tightly) and we can move onward.

The next instruction calls for adding a threaded rod covered with heat-shrink tubing to prevent shorting out any of the wires on the relay mount board. The threaded holes in the battery rack for the vertical thread-bars had powdercote in them, so I used two nuts tightened together on the top of the threaded rod to get more leverage to twist the rod into the threaded hole.

Next up is installing the auxiliary battery. This is rather tricky since you can see that the front edge of the battery is resting on the front hood latch. Earlier directions for mounting the front battery rack say to move the rack at least 2 1/2" forward of the rear wall. What this really means is that you need to mount the rack EXACTLY 2 1/2" in front of the wall so components on the front of the rack don't hit other parts of the car. If this has clearance issues, I might have to re-drill some of the previous holes to move the rack. This will be a royal pain after adding all the wires.

Okay, we now have all the wires from the fuel compartment with connectors on them attached to the battery or components on the relay mounting board.

In the process of attaching cables to the auxiliary battery, I got a click from the key-switch relay on the right and the DC-DC converter turned on (red light). I also got minor sparks coming from the negative terminal of the auxiliary battery. I suspect I hooked up something wrong and will reverse engineer the connections next.

I was somewhat blindly following the instructions up to this point so I'm guessing there's a bug. Also, the instructions for the DC kit may not apply to the AC kit. Here's where the real fun begins since there are no wiring diagrams from Electro Automotive for the AC kit yet!

Off to sleep to prepare for another day... Cheers.