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Old 11-19-2010, 02:40 AM   #4011 (permalink)
jyanof
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Quote:
Originally Posted by duncan View Post
I would like a panic button that tells the controller to cut current,
(my software could fail at some point!)

Should I do this by putting a switch in the throttle pot line?
Or is this a feature that should be added to the new board?
I'm of the opinion that a hardware interruption is safer than a software feature. You should have some way of de-activating a contactor in your battery circuit.

This could be a manual switch that's accessible in the cabin, a button that deactivates a contactor solenoid, or a handle that's connected to a circuit breaker under the hood.

my setup uses the switch on the pot box to cut out the main contactor so that every time the pedal is released, the battery is disconnected (except for the precharge resistor). This has the added advantage of stopping the car at the first instinctual reaction of the driver if something goes wrong (by lifting the foot off the accelerator) and actually came in handy when some internals of my controller shorted out (see post above).

Keep in mind that not just the software can go bad and that no software will open a mosfet that failed shorted (or a bolt that wore through the insulation and bridged B- and M- like happened to me).

Use the potbox switch does present timing challenges (the controller motor output must begin after the contactor closes and end before it opens). One option may be to use this method during your initial testing and resort to a big red button afterwards.

anyway, hope that helps.

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