MP4 wheel stuck at braking

[Daniil]

Hi everyone,

I have an issue with my 6 months old MP4 rear wheel and I was hoping that someone could advice me something. Thanks in advance. I have been using it extensively during this time without any trouble and it is very dear to me.
So the symptoms are as follows.
1. The battery charge LEDs suddenly turned off and the throttle stopped working.
2. The wheel suddenly became stiff as if I was holding my regenerative brake.
3. Even with unplugged battery the wheel is stiff as if I was holding the brake.
4. Replugging the battery doesn't make any change: LEDs are still off, the wheel is still stiff, throttle still doesn't work.
5. When I close the circuit with the key lock I hear characteristic spark sound in the battery.
6. Now the battery smells of burned rubber. I have opened the battery (48V10AH LiFePO4), and couldn't see anything burned. I haven't opened the inner blue thing though.

Any advice would be most appreciated.

Thanks again!

Best,
Daniil

[Bikemad]

Hi Daniil andto the forum.

From your description, it sounds like the controller has failed (probably one or more MOSFET has failed in a short circuit condition) and this is causing the stiff wheel in addition to overloading the battery and preventing the battery gauge LEDs from lighting (and producing the burning smell from the battery).

I suggest that you contact your supplier and explain the symptoms you have listed and ask for their help to get your motor working again.

Hopefully it will just be the controller that needs to be replaced.



Alan
 

[Daniil]

Hi Alan,

Thank you for your reply.

My supplier has asked to bring the kit to him. My problem is that I bought it in another country and bringing it back to the supplier will involve months of going to work by public transport:) I was hoping that I could get a new controller and simply replace the old one, but if you say that there is a little chance that this might not be enough than I guess bringing the kit to my supplier is my only option.That's so sad.

[Bikemad]

When the wheel is difficult to turn with the battery disconnected, it is usually just the controller causing the problem.

If you remove the controller and disconnect the three thick phase wires (Yellow, Blue and Green) from the rear of the controller and the wheel turns easily again then the controller is definitely faulty and will need to be replaced.

The Battery's BMS should have protected the battery against any permanent damage from the failed controller.

With a new controller, the motor, throttle and battery gauge LEDs should all begin working again as they did before the original controller failed.

Alan