Direct Drive motor gets stuck without power attached

Pegasus195

100 mW
Joined
Sep 11, 2016
Messages
40
Location
Java, Indonesia
Hi, I am currently building another ebike, with a DD hub motor. It's still on progress, and I'm hanging the bike's rear wheel so i can test run the motors without hesitation. It is all set except for the bike's battery & controller case, and so my ebike is hanging without any battery nor controller, just a plain bike with the attached DD hub motor. Sometimes, when i just spin the wheel with the hub motor attached, it won't do a "free-spin". It feels like there's a "force" that disable the wheel to spin. But sometimes this doesn't happen and it all works just fine. I'm just afraid when taking this bike to the road, the juice runs out, i can't even pedal the bike because the hub motor is having trouble with free-spinning. I can share you the picture or maybe a video if it helps.
 
When a DD hub motor locks up it is usually caused by a short circuit between two or more of the three phase wires. Try unplugging the phase wires from the controller first. If the motor will turn when disconnected from the controller the short is likely in the controller.
If it still won't turn, look for chaffing or damage to the wires, particularly where they enter the axle. Use an ohm meter to measure the resistance between the three phases and from each phase to the axle itself. I don't remember the resistance range between phases but it will be a few ohms and all three phases should be quite close to the same value. From the phase wires to the axle it should read open or a very high resistance. Mostly what you will be looking for is a zero or very small resistance reading.
Search the forum for for Phase Resistance.
 
It would be normal to feel resistance spinning the wheel backward if the controller is connected (even with no battery). With the controller disconnected from the motor, there should be no resistance either direction.
 
be sure and keep the phase wire connectors from touching each other when you spin the wheel. If one touches another, it will cause resistance.
 
No controller? If the phase wires are just hanging there, they're probably touching each other sometimes, which will do what you describe.

tie them down so they are not going to touch each other and it'll be fine.
 
Hwy89 said:
When a DD hub motor locks up it is usually caused by a short circuit between two or more of the three phase wires. Try unplugging the phase wires from the controller first. If the motor will turn when disconnected from the controller the short is likely in the controller.
If it still won't turn, look for chaffing or damage to the wires, particularly where they enter the axle. Use an ohm meter to measure the resistance between the three phases and from each phase to the axle itself. I don't remember the resistance range between phases but it will be a few ohms and all three phases should be quite close to the same value. From the phase wires to the axle it should read open or a very high resistance. Mostly what you will be looking for is a zero or very small resistance reading.
Search the forum for for Phase Resistance.
It appears that you and the others are right, the phase wires touched each other and lock the wheel from moving. Thank you, but will it damage the hub motor if I continuously force the motor to spin while he wires touched each other? will it damage the hall sensors etc?
 
No it won't do any harm. To protect wind turbines from overspeed and damage during storms the phases are swiched together to put on the brakes. As you have found it is quite effective.
 
Hwy89 said:
No it won't do any harm. To protect wind turbines from overspeed and damage during storms the phases are swiched together to put on the brakes. As you have found it is quite effective.
It is pretty effective, but seems dangerous. Thank you for the info
 
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