Burnt motor, flashing controller LED

[nastybyte_]

Hi,
my first post here, this really seems like an awesome place! Been reading for many good hours since i found it

Anyways, i bought an e-bike maybe 2 years ago, and for some reason the motor must have overheated - i took it apart and the windings were all black and scorched. First the motor was sometimes a lot more noisy than usual, while giving much less torque, this problem grew worse until it was completely unusable. (I know all too well that i should've tried to fix it back then before it went completely broke, just too bad i didn't ) So i bought a new wheel (got a used spare real cheap). Now when i connect it and turn on the battery key, there's a red LED flashing on the controller, and nothing at all happens when i pull the throttle. The controller is marked PS80A, the motor is manufactured by 8fun electronics, a 250W model with hall sensors.

Now i don't just want to get the damn thing back to work - i want to know what went wrong, so i can prevent it from happening again. I think it was really shitty weather when it broke down, the controller housing was probably soaked with mud. But the controller seems to have been well insulated, no signs of short-circuit or anything. My newly charged battery gives me 41.7 V. I tested the hall sensors on the old wheel and they're OK. Any ideas what more i could try, or what the flashing red LED means?

 

[dogman dan]

Windings that get cooked enough start shorting, when the varnish gets cooked away. Then shorted phase wires can fry the fets in controllers. That's the most likely thing to have happened.

Lyens sells a nice controller and motor tester if you really get into this.

But the main thing is not overheating the motor. When we hot rod ebikes, we often include temperature monitors.

 

[nastybyte_]

Thank you for the reply. After browsing this forum all day i feel a strong urge to really get into this!

Is this - shorted windings - a common problem with this kind of motor? I'm not an electronics expert (my official education is in chemistry) but i would've expected some kind of safeguard against this obvious hazard? Maybe it has something to do with the fact that i bought it in a local shop without even looking it up before, so it's probably the cheapest junk on the market.

Any idea what temperature these windings can stand, ~200 deg C? Would be fun to mount a temp.sensor and see how hot it gets. Speaking about modding, anyone know if there's an open source controller that would fit in an e-bike? Google gives me no good leads on this one... Also, when buying a controller, what do i need to specify? If i buy a controller for a 36 V 3-phase BLDC motor with hall sensors, should it just work or are there any pitfalls?

 

[docnjoj]

I would do my best to keep the motor below 200F if you want it to last. Almost all brushless controllers with hall wires will work with almost all motors. There is a section about color matching wires using either a spreadsheet or keep track and guess using very low amps to test the rotation of the motor. It should be smooth, in the right rotational direction andaround 1-2 amps unloaded max. I hope this helps.
otherDoc

 

[jateureka]

Not sure what model motor you have. 8FUN (Bafang) make a few different motors, but I haven't seen one that bunt out using a stock controller. I have seen chewed gear teeth and burn controllers though.