On Feb 25, 2013, at 3:24 PM, Lee Hart <[email protected]> wrote:
>>>> Typical way to use [the inertia switch] is to wire it in the >>>> circuit that engages the pack contactor coil (so, a 12V >>>> circuit). If the switch opens after an accident, the high voltage >>>> from the pack is interrupted because the contactor(s) drop out. > > Steve Clunn<[email protected]> wrote: >>> Some controllers and most contactors aren't happy being opened >>> under load. > > Things obviously last longer when *not* asked to break high current. > However, it is sometimes necessary to do it anyway (such as in an > accident, or to stop a runaway controller). > > corbin dunn wrote: >> Really? which ones? Most should handle this okay. I know the Netgain >> brand controllers are fine. > > It isn't brand-specific; it is circumstance-specific. > > Most controller skimp on the size of their input capacitors. They depend on > the battery to handle at least some of the inductive energy that "kicks" the > voltage up when the controller shuts off. > > If the controller is operating at high current, and the battery suddenly goes > away, the voltage on the capacitors and transistors will spike up much higher > than normal. If the EV has a large design margin (like 250v parts with a 150v > pack), it will survive. But if the controller has 200v parts and the pack is > 144v (and at 180v because it was just charged), there is not enough safety > margin and the controller can blow. > >>> I've been hooking the Inertia switch to turn off the key input to >>> controller. > >> I think that defeats the purpose of the inertia switch. > > The inertia switch is supposed to *absolutely* shut things down in case of an > accident. But one possible reason for an accident can be a runaway > controller! So, it is best if the inertia switch shuts everything off that it > can (controller *and* contactors). Good point! I should have been more clear: I have mine wired up in exactly this way. The switch cuts off the 12v key-on input into the controller, and the 12v power into one contactor. corbin > > -- > *BE* the change that you wish to see in the world. -- Mahatma Gandhi > -- > Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
