Sunday, March 14, 2010

The Electric Car Resurrection II: The Hero's Path

While I was researching conversions, I found out that the husband of a friend of my wife's was planning to do a conversion. Steve Schmidt and his son Eric (a high schooler) were well into plans to locate a small junked sports car in good condition and convert from ICE to EV. Now,  Steve's skill with tools is far in excess of mine, and Eric is no slouch himself. Eric recently served as lead engineer on one of the components in his high school robotics team's entry into the national robotics competition. I'd last checked in with Steve two years or so ago, so a few weeks ago I stopped by to see how the project came out.

Steve and Eric started planning the conversion in the spring of 2007. They ordered the batteries in September, 2007 and by February 2008 the batteries had arrived. The conversion work itself followed quickly, by May the car was running.

The "donor" was a 1976 MG midget, located from a junk yard and bought for $800. Here you can see it relaxing in the grass:
The first order of business was restoring the car's gasoline engine. This they did. Here you can see the car with the engine restored, minus the radiator:

Naturally, if you want to get a car relicensed in California, you have to have a smog inspection. Since this car had no pollution controls - catalytic converter, filters on the engine to catch gasoline vapors, etc. - it was labeled a "gross polluter". But they did manage to get it relicensed. The work on the gasoline engine wasn't all lost, they managed to sell the engine on EBay which helped finance the electric components.

After the car was running on gasoline, they removed the engine and started the electric conversion. The most difficult thing about the conversion was connecting the electric motor to the transmission and clutch. Most electric conversions remove the transmission and clutch. Because an electric motor has essentially infinite torque at zero rotation, there is no need for a transmission, unlike a gasoline motor. But Eric really wanted the ability to shift, so they kept the transmission. The connection required them to get a specially machined metal plate to match up the motor to the transmission. This plate is actually a requirement for any electric conversion, but theirs was a bit more tricky because they wanted to keep the transmission.

The most expensive part of any electric conversion is the battery pack. Unlike most hobbyist conversions, the Schmidts decided to go with lithium polymer batteries, having lithium cobalt oxide anodes. They ordered their pack from ABAT, a Chinese company, and the batteries also came with a battery controller for charging. The pack consists of 66 40 amp-hour cells arranged 2x33. The result is 80 amp-hours at 130 volts, or 10 kWh. Here's a picture of the battery box in the front:

There's another battery box in the back where the gas tank used to be.

Shortly after they got the car running, 2 cells went bad and were replaced by ABAT on warranty. They now have two other cells that don't charge up as smoothly as the rest. the line of small dots you see on the front of the battery box are ports they use for balancing the charge across the two strings of batteries. The battery pack cost around $10.5K and weights 200 lbs. though all together, it did not add extra weight to the car. The car is actually slightly lighter than the original but still has the original suspension.

The other electrical components include an Advanced DC 8", 85 hp motor and a Curtis 1221-C controller. The controller is a bottleneck, it will not let the motor draw enough current to get that slapped back into the seat kind of acceleration that electric cars are known for. Steve told me that there is another controller, made by Zilla, which is much better but it is considerably more expensive and also isn't manufactured any more, so it can only be bought used. Because the electrical system is DC, there is no regenerative braking, such as the Prius and other commercial hybrids have.

The range of the car is around 45 miles per charge, top speed probably over 65 mph but they have never tried it. Steve and Eric told me of their adventure with getting the electric car smogged. This sounds like a contradiction, but after they removed the engine, they had to have it retested and certified as not being a polluter. DMV was around 20 miles away,  so they figured they could just make it. On the way back, they almost made it when they realized they were running out of charge. They parked the car at a laundromat and plugged in for a couple hours. After that, they made it home. But the car is mostly used by Eric for commuting 5 miles or so to school and back, so range isn't really a problem.

Eric and Steve split the financing. Eric paid for the ICE components, including a new set of seats from a Mazda Miata and a stereo, and Steve paid for the electric components. In all, the cost came out to $18,266.

After we were done talking, Eric took me out for a spin. The land around their house is hilly, but the car had no problems negotiating the hills. And despite the drawbacks of the Curtis controller, the acceleration seemed just fine.

If you want to find out more about the Schmidt's conversion, check out their Web page at EValbum. com.

1 comment:

  1. That's a pretty cool car for driving back and forth to school!