LewTwo
1 MW
Well it finally happened: it died. I was coming back from the grocery store and everything was fine … then it happened: complete shutdown. Cycle the battery on and off …. nothing. Turn on the power and the motor goes bump and then absolutely nothing.
Unplug the system and check battery voltage … 40 volts (pretty good for a six year old 36 volt LiFePo4 battery). Plug it back in, turn on the battery and the power immediately drops to zero. Unplug the throttle and same, same. Unplug the motor and power to the controller stays on with 40 volts on the input. It appears that the BMS immediately shuts down the system when it starts feeding current to the system. I think it is detecting a direct short.
Motor: Bafang WSXU geared front hub motor
Controller: S-KU65 DC-24 to 36 Volts
Motor spins freely forward, cogs when turned in reverse.
Hmmmmm … unplug the battery:
check the resistance through controller and motor: 4.5 ohms
unplug the motor
check the resistance through the controller: 1.5K ohms … rising
check motor phase:
Yellow to Green = 0 ohms, generates current when spun backwards
Green to Blue = 0 ohms, generates current when spun backwards
Blue to Yellow = 0 ohms, generates current when spun backwards
I have one of those Brushless Motor/Controller testers but it’s connectors have no resemblance to mine. That is because I have a Julet 9 conductor motor cable hard wired to the controller. Might have to hard wire Julet male/female cable pair to the tester.
Removed the controller and took it apart. One solder join for the power shunt melted and dripped down to the case leaving a scorch mark on the rear cover plate. Also found another smokey bit on the bottom of the circuit board.
At this point all I want to do is verify that the motor is still good … not sure how to do that without a known good controller.
Unplug the system and check battery voltage … 40 volts (pretty good for a six year old 36 volt LiFePo4 battery). Plug it back in, turn on the battery and the power immediately drops to zero. Unplug the throttle and same, same. Unplug the motor and power to the controller stays on with 40 volts on the input. It appears that the BMS immediately shuts down the system when it starts feeding current to the system. I think it is detecting a direct short.
Motor: Bafang WSXU geared front hub motor
Controller: S-KU65 DC-24 to 36 Volts
Motor spins freely forward, cogs when turned in reverse.
Hmmmmm … unplug the battery:
check the resistance through controller and motor: 4.5 ohms
unplug the motor
check the resistance through the controller: 1.5K ohms … rising
check motor phase:
Yellow to Green = 0 ohms, generates current when spun backwards
Green to Blue = 0 ohms, generates current when spun backwards
Blue to Yellow = 0 ohms, generates current when spun backwards
I have one of those Brushless Motor/Controller testers but it’s connectors have no resemblance to mine. That is because I have a Julet 9 conductor motor cable hard wired to the controller. Might have to hard wire Julet male/female cable pair to the tester.
Removed the controller and took it apart. One solder join for the power shunt melted and dripped down to the case leaving a scorch mark on the rear cover plate. Also found another smokey bit on the bottom of the circuit board.
At this point all I want to do is verify that the motor is still good … not sure how to do that without a known good controller.