Shorted phase wires? (HS4040)

sgds23

100 mW
Joined
Sep 19, 2012
Messages
35
I recently hooked up a new Crystalyte HS4040. Initally, it ran, albeit poorly (I later discovered an intermittent connection on one of the Hall wires). But after riding it for a few blocks, the motor gave up the ghost, and now will only do a half-hearted jerk on startup.

I took a multimeter to it, hoping to discover it was just a bad connection, but instead discovered that all three phase wires are now shorted together. It has to either be happening inside the motor, or in the first few inches outside, and since I can't see any problems with the wires, so my money is on the former.

My question is... is this a common failure? was it potentially the result of running with a bad hall sensor connection, thereby frying the motor? (I find this hard to believe since my controller detects stalls and limits amps, but it's the only thing that comes to mind.)

Oh, and one other odd thing. You know those cheap chinese brushless motor/ebike testers? I hooked the phase wires up to that ("motor coil test") and the LEDs blinked in series just like they should.... how does that make any sense??

thanks,
s.
 
Unless you have a meter that can read milliohms and lower, all phase wires will always appear shorted together, on typical multimeters.

If they were actually shorted together, the motor woeuld be very hard to spin even when not connected to the controller.

Most likely you have a bad connection either in hall or phase wires between motor and controller, or you have a bad controller, or a bad hall sensor.

If the tester sees all the halls ok, then that's eliminated, leaving the other two.
 
...he says that "...it initially ran, albeit poorly"...

possibly a false positive - then ridden with - would be very hard on the controller and potentially overheated the motor, even after a short run.
 
Thanks, Amberwolf-- I should have realized that about the phase wires. Whoops.

I'm still scratching my head about what could be wrong, given that the tester seems to indicate both phase wiring and halls are ok. (And I've tried 3 different controllers..)

I guess I'll try some more fiddling before I start doubting the tester..

thanks,
s.
 
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