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.