Geared hub motor won't work, hard to roll backwards

I have a bafang geared rear hub motor in a fat bike. Recently while riding the throttle stopped working but I already had a new controller in the way so I didn't worry about it too much. The old controller had a modified shunt. So after installing the new controller the motor still won't work, I've tried 2 different controllers, 3 different displays, 2 different throttles. I tested the phase wires from the motor on my tester and multimeter and they seem fine, except the wheel has a lot of resistance when I roll it backwards. Does any body have any ideas what could be going on?

I've had a problem where 2 of my throttles were bad.

https://ebikes.ca/learn/troubleshooting.html
Testing a Throttle

Geared motors are supposed to be hard to turn backwards... That's when you're actually making to motor turn inside the outer shell... When you spin it forward the clutch releases and just the outer shell turns, unlike a direct drive where it feels the same both directions.
As to why it's not running, what test did you do on the wires?
And are the displays lighting up and acting normal, just no spin at the motor?

It's more than a little resistance going backwards though. It's clunky. Like dragging a heavy chain over a ledge.

I checked the resistance in the phase wires with my multimeter. They were all similar. I used a ebike tester to check the hall sensor wires and the phase wires. That's when I rolled the tire backwards to get the lights to turn on and noticed how stuck the wheel was. But the tester did recognize the phase wires and hall wires.

I've hooked up a second brand new controller to see if I just had a bad controller, same results. I tried multiple different displays and throttles. Brand new stuff. I've opened up the motor casing and it looks like new inside.

Here's the ebike tester

Being extra hard to turn is sometimes a sign of the phase wires being shorted together...

Cogging is what is usually called... Normal backwards spin on a gear motor should be harder than forwards, but like a gentle whirring, not super notchy.

If the phase wires were shorted wouldn't they have a bad reading when i test them?

Could be crud gumming up the motor, bad motor bearing or something jammed between the stator & magnets. Seems the motor is seized. You only feel it when you turn the wheel backwards & the clutch engages.
Keep us updated on what you find mate.

AussieRider

The tester link didn't show up...

Did anyone figure this out? I've having the exact same issues on a Bafang G06 rear hub motor. Stopped working. while it was working itmade some funny noises, a few odd skips and jerks and then dead. I took the motor out and the resistance spinning it backwards is very high and has an odd jerkyness to it, "like pulling a chain".

Each failure can be different, so you would have to check your actual motor for what is causing it's problem.

Possibilities include but may not be limited to:

Broken gears, shorted windings or phase wires, debris inside motor bell jamming rotor to stator, etc.

If the feeling is more like a rapid periodic resistance that gets weaker and stronger, it is probably a winding or phase short between two or even all three phases.

If it only happens when connected to the controller, it's the FETs in the controller that have failed. If it happens even when unplugged from everything, it's in the cable between the plug and the motor internals, or the windings themselves.

Usually a short of this nature happens from overheating, damaging insulation by melting/etc, so it may start with a little problem then suddenly get much worse after enough overheating.

A phase short also usually damages the controller itself.


If the feeling is a slow periodic or semiperiodic "thunk" it could be broken gear teeth or debris in the motor bell.

I've shorted two phase wires intentionally and tried to turn a geared unit backwards. Wow was it stiff. Then I unshorted the wires and it spun again. You're doing this test with the motor unplugged?

Maybe two or more phase wires are short circuited inside the motor cable where they got hot and you could fix that. I believe the phases are under an ohm in resistance, so it's hard to tell between a short and an unshorted wire.