E-bike motor/ESC problem

[Long John Rider]

I'm running a 500w gearless motor.
36V battery, which is healthy, no dramatic voltage drops under load.

This is my speed controller since about a year: http://s.aliexpress.com/yUBfiYbQ
I have a brake switch for regen braking, a toggle for cruise control, a toggle for limited speed, and a thumb throttle. No pedal sensor, and the hall sensor wires are not connected.

My wife rides the bike too, and reported what I believe to be the same problem as I have since this morning about a month ago, although it reportedly fixed itself and has been working since, until now:

When I flip the master switch (big dumb circuit breaker between battery and ESC) I get a few seconds of motor power before it stops, and it won't turn over until I cycle this breaker, when I get a few seconds again. I get no regen braking either when the motor is dead.

Is it simply a matter of replacing the ESC, or it there something else I should look into first in the rat's nest of wires and connectors? Is there a broken connection or short circuit that would produce what I'm seeing?

I could relatively easily try another thumb throttle which I have at hand (though I don't see why this should be the problem, it's just the only electric part that gets wet all the time I guess), less easily put my old non-regen ESC back in as a stopgap while I wait for a replacement regen-brake equipped ESC to arrive on a slow boat from China. I'd rather not go through all that hassle though, obviously, if this is something else that I can try. I just don't know where to begin to effectively troubleshoot this.

Any ideas or suggestions would be greatly appreciated.

 

[amberwolf]

It sounds like a power problem. Do you have a power indicator, voltage meter, watt meter, etc, that is also after the breaker? If so, does that also not work when you have this issue, or is it working normally?

If it is not working normally, the breaker itself could be the problem, where it is not switching correctly. Or there could be something with a poor connection somewhere.

 

[MadRhino]

+1 for the circuit breaker. This is unlikely to live very long switching DC at its max Amp rating. Bypass, plug your controller direct on the battery. If it does work again, install another switch. Your controller must have other mean of switching on/off. If it doesn't work, then check wire connectors and all the wiring circuit integrity.

 

[Long John Rider]

I don't think it's the circuit breaker for a few reasons (though I will certainly look into it as suggested):

-It's a breaker rated for 100A continuous and 250A momentary load, pretty well weatherproofed. It should be plenty for the job. It's never turned on/off when there's a significant load either, just a few watts of LEDs at most, so it's not like there's arcing going on in there on the regular.
-Parallell to the ESC/motor there's a voltmeter, showing nominal voltage throughout my frustrated attempts today
-horn and lights also work as they should, so do the LED voltage indicator lights on my thumb throttle.
-every time I reboot the ESC, I get exactly the same period of motor function before it dies.

A thought, possibly stupid: The ESC is supposedly for both 36V and 48V systems, with undervoltage cutoff set at 31.5/42V respectively. I have no idea how it "knows" which of these two alternatives my battery voltage is supposed to be, I certainly never programmed it or set any switch/cable for 36V operation. Is it possible that the ESC somehow suddenly thinks I should have at least 42V and cuts off when it senses 41V like I had today?

 

[MadRhino]

Have you checked all wiring and connectors, before and after the controller ? If so, you can presume the controller is at fault. If it is really working on both voltages with some detection program, then it is when powered above the 42v cutoff voltage that it would trip to the 48v setting. Then, your guess that the fault is in that detection condition, may be right. You would need to power it at 48v to know.

 

[Long John Rider]

I've checked the wiring I could easily get to, and bypassed the circuit breaker in order to rule it out. No change. I've ordered a new ESC (they're cheap enough) and will try to do a deep dive into the wiring this weekend to see if I can get it running.