For two reasons: the supplied controller was defective, it made the display stay on all the time, the firmware available for the V3 was not suitable for my use.
I'm having the same problem. 700Wh battery with flashing third LED. I read about some company replacing the BMS with a compatible one. Can you tell me anything about this?
FC3.0 has an updated torque sensor, but is compatible with V2.0/2.1 controllers.
I have an FC3.0 motor that I fitted with a V2 controller to and it works perfectly.
I just finished assembling this BXT-EMTB-217 M size with Bafang M510, battery 840Wh, extender predisposition with bottle attachment up to 520Wh, front/rear lights with display switch-on.
If it is a new controller it may not have the serial number.
If you have BESST account, you can set the serial number you want, read the one of the old controller.
With K1 you can avoid, because it does not require knowing the serial number.
I use K1 BBR always connected to the controller, it...
Leave the cables separate, the positive and negative output on the outside, the positive and negative charge on the inside. If necessary, connect the positives together but leave the negatives separate.