Think I just blew my controller too

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antiscab
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Joined: 07/07/2007
Points: 1686
Re: Think I just blew my controller too

Hi Colin,

to get a better idea, have a look at the circuit diagrams here:
http://en.wikipedia.org/wiki/Buck_converter

a motor controller is built much the same, however, the capacitor on the output doesnt exist.
the inductor and resistor are the motor inductance and resistance, so these arent inside the controller either.
additionally, many capacitors are added to the input side of the controller to reduce the current ripple the battery sees.

In essence what happens is,
when the gate(s) is on, the motor sees full battery voltage, and the batteries see full motor current (minus what the caps on the controller input filter out).
when the gate(s) is off, the battery sees only the current drawn by the input caps to recharge.
the motor current flows through the freewheel diode.

so at 50% duty cycle, the battery sees on average half motor current, and the motor sees on average half battery voltage.

for a 3-phase AC controller, there are actually 6 of these buck converters, one for each direction of current flow of each phase.

hope this is helpful,

Matt

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dogman
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Joined: 04/29/2008
Points: 830
Re: Think I just blew my controller too

I don't think the ecrazyman controller on the link you sent will work with a WE motor. That controller has hall sensor wires, so its not a pedal first, or sensorless controller. Last time I looked, crazyman didn't have any sensorless posted but that could change anytime. Other ebay vendors might, but I don't know. It's a lot of money for the big 72v controller, but at least you won't have to worry about 58v of ping. The ebikes-ca controllers are different from others, and most report good results with them.

As for discharge rate, I have yet to see any brand of duct taped lifepo4 pack test results at a rate over 1c. So running at rates much over that is your experiment. Let us know how it comes out, we'd love to have some real world results. Till then, you CAN find people who did discharge at higher rates posting about thier problems, and of course, we don't hear much from people who don't have problems. The new ping v2 cells are claimed by ping to be 2c capable. If so, post the test results. All he shows is a 1c test, so that is a 1c cell to me.

I do agree that slower charging and discharging, keeping the pack between 20% and 80% state of charge is the best strategy for battery life. I don't think 5 amp charging of a 20 amp ping is a problem though, it's only .25 c charging rate. I'm getting good results from my ping v1 pack, but I don't run big motors on it. But I have run it hard, and gone to cutoff more times than I expected to. If I get wind in the face going home, I may not make it, since its 15 uphill miles. So my real world experience is, calculate what you need, then double it.

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Arno J. Wulfert
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Joined: 08/12/2008
Points: 94
Re: Think I just blew my controller too

Thanks Dogman,

I'm going to spend the money and go with the 24V - 72V pedal first Crystilyte... I'll be on the phone to order today... I will follow up with a post after I've got it hooked up... Now, I pray the problem is nothing to do with the motor...

As far as 1C or 2C, I don't have a clue what that is about.... I'm just going to hook it up and ride...

Cheers and Thanks again,
Matt (ajw)

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