Help troubleshoot jerky acceleration, hubmotor fail?

[Allex]

Helping out with a scooter here and right now I am not sure what it is, maybe you can help out?
It is a 16s40Ah lipo4 scooter with a quanshun like hubmotor stamped 2000W on it.
18FET 50A controller

The problem. When standing still and whacking the throttle it does accelerate very slow and jerky, like the motor shuts on and off. When applying light throttle on a flat ground, there is no problem.
So ok, I test the batteries and BMS, no problems there.
Checked the halls, and they all read 0-4,xx volts
Swapped to another controller, an Adaptto, it did autodetect (it does choose phase combo and hall combo/alignment automatically)without a problem. So I did a test drive and as soon as I apply more than ~10A the controllers cuts the load and the adaptto screen screams !HALLS!
So Ok could it be the halls anyway? I swap the mode on the adaptto from sinewave to sensorless and now there is no cut outs and no jerky acceleration.
Could it really be the halls, and in this case, how can they still measure 0-4,xx volts?

I remove the motor, and see that one of the phase wires have scuffs, it was chaffing on the metal scooter chassis.
My question now is, is it worth swapping the halls or could the whole motor be ruined by rust?


Rust:


Halls:
View attachment 1

Phase:

 

[John in CR]

I wouldn't change the halls unless I was sure one wasn't working. Unless it blew them with the last attempt, it's probably just a scuffed all wire too which was intermittently shorting with the phase short. The lesson to learn from this is when you have a problem, don't continue to try it until something has been fixed. It's not like a gasser where it could solve anything by running it a bit, and there are electrical problems that can rapidly get worse. eg That phase short could have easily blown a controller.

Also, get yourself an ebike tester to make your current hall tests simple. OTOH that phase short could have been easily diagnosed with no tools by spinning the wheel by hand with the scooter off and wiggling the wiring harness while you turn it.

 

[Allex]

Thx, I isolated that phase wire and tried again, but the problem was still there.
Could it be something else,? The motor works perfectly fine while of the ground, it can do low/mid/full throttle but as soon this happens under load, then it start to jerk/yank.

 

[mistercrash]

Looking at how the inside of this motor looks, I assume the rest of the scooter is not well kept either. I would check every millimeter of the three phase wires and of the five hall sensor wires to make sure there is no other short to be found. Check the connectors also. When the motor is nice and tight in the swing arm, does the motor twist a tiny bit when you whack the throttle? If there is frayed wires you haven't found yet, they might short when the motor twists a tiny bit when whacking the throttle but they don't short when you apply smooth throttle because the motor does not twist. Just talking from experience here has this problem happened to me once on my own scooter. Good luck and I hope you cleaned that stator and rotor before you closed that motor.

 

[Allex]

What about loose strands on the stator itself, could they interfear in such a way? Some of them does not look very good.

 

[Allex]

Got it sorted, but dont know what it actually was. Inspected every wire and maked new isolation everywhere. Cleaned up the stator halls and rotor from rust. Now the symptoms are gone.