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).
--
*BE* the change that you wish to see in the world. -- Mahatma Gandhi
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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