Electric Cars

Tweety - my Corbin Sparrow"

In April 2000, I ordered a Corbin Sparrow. I got reservation #190 then. At the time, they'd just delivered #61, which led me to expect mine around the end of the year. Shortly thereafter, in June, #67 was put up for sale by someone in Seattle who wasn't the early adopter type, and I decided that it would be a good way to get into one quicker. I knew they were early in the production cycle, and constantly improving them, so I kept my order in with the intention of selling the older one when the new one became available.

It blew a controller after a few days of driving; I sent it in to the people that build the controllers (not Corbin) and 3 weeks later, I had a new one with beefed up electronics. A few days of driving and it too let the smoke out (you know electronics run on smoke --- if you let it out, they stop working...). Sent it back, and about 3 weeks later got a third one. This time they'd figured out that the motor was sucking way more current than expected, because the Sparrow is a direct drive vehicle --- no transmission. As a result, this time they sent me the 1200 Amp model instead of the 600 Amp model originally installed and I never had *controller* problems again.

In late August, I went to the electric vehicle drag races at the Woodburn drag strip. I'd only intended to display the car, but there was another Sparrow there, and I was curious what the 1/4 mile time actually was in it, as it is a peppy little vehicle. Well, it turns out that brush timing is important in DC motors, and as shipped from the factory, pushing a lot of amps at highway speeds isn't a good idea. About halfway down the track, my motor sputtered as it turned into a stroboscopic arc lamp. I backed off, but the damage was done...

This is called "flashover" and happens because as the commutator rotates away from the brush, a small spark is created until it gets far enough away that the electricity can't jump that far. Except that distance is larger with more current, and at high enough currents, the spark never stops and gets carried over to the next brush, which is oppositely charged. Voila! High powered arc welder.

The problem can be avoided by adjusting the brush timing in a way I don't fully understand, but was given specific instructions on how to adjust the brushes in the new motor to keep this problem from recurring. I got it put back together with the new motor so adjusted, but then it had a number of other problems including a broken drive belt and loose throttle linkage that put it out of commission. After I got the throttle linkage fixed and then it quit barely two miles later (apparently a loose connection the "main contactor" [main power switching relay]) and I let it sit so long the batteries got drained by the regulators I put on them to keep them balanced. Draining a lead acid battery ruins it. So, I sold it in early 2002 to someone who wanted to tinker with it and I'm on the lookout for a "real" car, probably a conversion...

Oh, and the Sparrow I originally ordered finally went into production in early 2001, but by then I'd put enough into fixing problems with the older one that I sold the new one to PGE before it even came off the assembly line. It can be seen still running around Portland occasionally.

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