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Old 11-19-2010, 01:54 PM   #4019 (permalink)
jyanof
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Quote:
Originally Posted by bennelson View Post
Ah yes, I remember reading that.

My potentiometer has the micro-switch, which COULD be used to turn the main contactor on and off as you press or release the accelerator.

I do NOT have it hooked up that way. To me, that always seemed like overkill. And a lot of going "clack clack clack".
To each his own... the contactor is barely audible and is a small inconvenience for the advantages provided, the most basic being that the motor will never get power unless commanded to by my foot.

Quote:
If you have the pot micro-switch rigged to the main contactor, that means that you already have the car in gear when your activate the main contactor. (Right? Why would you press the accelerator unless you wanted to drive?)

If you have a device that fails in the ON position, and it is most likely to fail right when you turn it on, and it gets turned on by being in gear and pressing the accelerator......

Hmm. Just doesn't sound like a good policy.
All gasoline cars are designed so that they have to be in park or neutral to turn them on.

An electric car should be the same way.
I think you have a separate argument (starting the car in neutral) than actuating the main contactor with the pedal. I think the neutral thing is good practice, but I take a calculated risk with my setup by not doing so. If 150V is applied directly to my motor when it's in neutral, it'll overspeed and explode. I will never turn the car 'on' in neutral for this reason, but run the risk of the controller failing while in gear. Hence, the reason for my overkill pedal/contactor arrangement.

When my controller failed, I would've been out a $1500 motor too if I started in neutral. Others might accept this as a price for added safety, but instead, the cost was just a few electronic components despite being just as safe (as evidenced by actually experiencing a failure).

Additionally, I would argue that one of the controller's failure modes is something blowing when it first is commanded to conduct current after it has already been turned on. I think there have already been several examples in this thread of this (yours and mine are the only case I recall where something failed beforehand). In my case, the failure was unrelated to things getting switched on or off and could have easily happened while in the middle of driving. In this case, starting the car in neutral would not help and some sort of emergency disconnect is required. If there's not much room in the direction the car is going, things gotta disconnect fast!

So, I agree that starting in neutral is probably safest. I still argue that having the pedal actuate the contactor is also safest.
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