Wednesday, December 31, 2008

Battery Degradation

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

Friday, October 17, 2008

Fixing the Aux Battery Killer

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.

Tuesday, October 14, 2008

Quirky Porsche Features Killed my 12V Battery

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.


Sunday, September 14, 2008

Just passed 6000 miles and fixed PakTrakr Issues

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

Monday, April 7, 2008

Switching Gears and Moving On

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

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.


Saturday, April 5, 2008

Going back to CAMP914

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.


Saturday, March 29, 2008

Going to the Portland Better Living Show

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.

Friday, March 21, 2008

Installing LED Lights and Fixing the LED Flasher

I received a shipment of 3-watt LED lamps and a low-load flasher relay from 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.


Thursday, March 6, 2008

2000 miles and counting

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.

Saturday, March 1, 2008

Fixing PakTrakr Signal Integrity

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 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

Many months ago, I installed a PakTrakr ( 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 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...


Sunday, February 24, 2008

Charging Up on Roadtrips

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.

Saturday, February 23, 2008

New Brakes and Local Lithium Supplier

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.

Tuesday, February 12, 2008

Magazine Article and 914 EV Wiki

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

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.

Saturday, February 9, 2008

Reflections on Converting a 914 to an EV

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, 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 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 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 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 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 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

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.

Thanks to everyone for their support on this project.


Friday, February 8, 2008

New Tranny Fluid, Battery Filler and EV Toolbox

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.


Thursday, February 7, 2008

DC-DC Installed and New Brake Parts

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 I highly recommend joining or 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.

Wednesday, February 6, 2008

New DC-DC here and Tranny Fluid Too

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. 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.

Monday, January 28, 2008

Opinions and Rants

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 and 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.


Sunday, January 27, 2008

DC-DC Overcurrent Malfunction

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.

Friday, January 25, 2008

Watt-Hour/Mile ratings and Selling the Trannies

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.

Tuesday, January 22, 2008

First Day Commuting with the New Tranny

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.

Thursday, January 17, 2008

Up and Running Again!

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.

Wednesday, January 16, 2008

Yay! Less Vibration!

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.

Tuesday, January 15, 2008

New Tranny Here - Salvaging Cracked Parts

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....

Friday, January 11, 2008

Rebuilt Transmission Coming Tuesday

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 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.