Repairing ebike motor electronics
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Repairing any ebike mid-drive or hub motor electronics with an external Chinese motor controller
I often get questions about repairing defective motor electronics of ebikes caused by, for example, water leakage. Repairing electronics of mid-drive electronics is particularly difficult because the electronics have to be removed out of the motor-housing in order to be able to do measurements. Then, however, the cooling of the PCB is lost and all wiring has to be extended. This is a lot of work to do and you don't know yet whether repair is possible anyway. But you can repair any ebike motor by simply replacing all the ebike electronics by a cheap external motor controller. Note that the speed control of these operates normally by a throttle instead of being dependent on pedal-force as you may be used to.
Repairing any ebike mid-drive or hub motor electronics with an external Chinese motor controller
The original parts of your ebike such as the motorcontroller, display, Hall sensor, torque sensor, thumbswitch etc. are no longer needed and can be removed. The new controller has to be connected to the three windings of the motor. If the motor turns the wrong way, then swap 2 wires. Connect the associated speedsensor, throttle, display etc. according to the user manual.
How to use the original battery
It is possible that the battery switches off itself if the original motor controller is missing. Then it may be necessary to connect another BMS in the battery to make the voltage available. For a Yamaha system you can use my Yamaha hacking dongle.
Yamaha battery dongle PCB
Gazelle repair
See here how a Gazelle ebike with hubmotor was repaired.
I know this description is very brief, who wants to complete this guide?