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Technology Stocks : Energy Conversion Devices -- Ignore unavailable to you. Want to Upgrade?

To: Krowbar who wrote (3918)	8/7/1999 9:09:00 AM
From: fred whitridge	Read Replies (1) \| Respond to of 8393

Del-- I'm far from an expert on high voltage DC. My VW cabrio is 120volts and my truck is 144volts. Each of these traction pack voltages is isolated from the frame. One of the safety tests the Tour de Sol runs on all vehicles is a "leakage test" where they measure the amount of current running from the most postive and most negative traction pack terminal to the chassis. I forget what the exact requirement is but it is in milliamps. You can get this sort of current return path by grime on the tops of batteries, wet batteries, etc. I would expect that early implementations of higher voltage vehicles might have both a 12volt and a 42volt circuit-- changing everything over at once would be a major undertaking. Certainly the GM divisions have been talking this way. In keeping with this cumbersome implementation they will no doubt tie both the negatives (on the 12volt and 42volt packs) together and wire the positives to each individual device. Then a few shorts of high voltage power to lower voltage devices by a shade tree mechanic or two will result in going to one voltage for the whole car and isolating the chassis from the battery. I'm not sure we'll get there in one step.