On 9 Oct 2002 at 13:20, Seth Murray wrote: > unless I'm mistaken, what Rich is saying is that if you properly design the > car, isolating the charger isn't really an issue.
It's a laudable goal. But there are few environments tougher to keep clean and dry than a vehicle. If you hermetically seal the battery case (hard to do), you have heat problems and trapped condensation. Open it for ventilation, and you get dust and more moisture. Every connection in that battery pack is another point of potential leakage current, even with "sealed" batteries. True, grounding the car and using a GFI is of some help. But what about those times when you're charging somewhere and can't get a good ground? And how many BC-20 owners have cheated the GFI so they could get a charge in spite of the leakage current it was detecting? And -- is your EV really grounded? Are you sure? Have you tested the ground to see if its resistance is low enough to clear a ground fault? Are you using a GFI ~every time~ you charge? When did you last test it? They are not foolproof. If the charger is fully isolated, the power line connection stops at the charger. Instead of all those battery pack connections, you have only a couple to deal with. If you have isolation (of both charger and battery), verified vehicle grounding, and a GFI, nobody can say you're not doing everything you can to make your EV safe. With all due respect to Rich, it's not that tough to make an isolated charger. Rich has said he could make it isolated and probably will eventually make that an option. But he has written here before that he hasn't yet because it would make the charger cost too much. (Rich, if I'm misquoting or misunderstanding, please correct me.) And it's true, a lot of EV hobbyists are too cheap to pay another $200 or so for isolation. But I happen to think $200 or even $300 is a reasonable price for long-term insurance against electric shock which can and does KILL people. Think of the 5 year old neighbor kid who wanders over for a look at your car while it's sitting in the driveway charging. Maybe you just washed it, and the ground is wet. He's barefoot. You're inside. There's a ground fault. He dies or is injured. This can happen. The more EVs we have in the field without isolation from the power line, the more likely it is. The media already love to make sensational stories bigger, especially if they can knock down EVs at the same time. When something like this happens, we can expect a news media feeding frenzy. I know some people don't agree with me. You're all welcome to your opinions, welcome to mutter about what a overly cautious mother hen I am. Fine; go right ahead. Nor do I want to make Rich or anybody else sore at me. But I'm going to keep saying this because I think it's important. It's about human lives. Please, folks, isolate your EVs from the power line. Use an isolated charger. We CANNOT afford to have EVs labeled "killer cars." = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Want to unsubscribe, stop the EV list mail while you're on vacation, or switch to digest mode? See http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = David Roden - Akron, Ohio, USA 1991 Solectria Force 144vac 1991 Ford Escort Green/EV 128vdc 1970 GE Elec-trak E15 36vdc 1974 Avco New Idea rider 36vdc = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Thou shalt not send me any thing which says unto thee, "send this to all thou knowest." Neither shalt thou send me any spam, lest I smite thee. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
