Hey guys I'm having a issue with a 750w bafang motor and the other day I was riding it and I felt a strain on the motor followed with a wierd sound for a brief second ir stopped running then started again and it felt normal after about 10min after turning the bike off and back on the motor wont run.. I opened it up the clutch and gears look fine the magnets look good but wont run please help
Electric hub motor
- Thread starter Ace215
- Start date
dogman dan
1 PW
95% of wont run problems have to do with wiring, usually the plugs. Check all of it, look hard. Then do it again and see instead of just looking. Start at the battery, and go from there.
The most common problems, in no particular order:
Connections between motor and controller. Can be anything from the wiring inside the motor and controller all the way thru the connectors to inside the controller, but is usually at the connectors themselves, not being fully plugged in (common with waterproof connectors cuz they're harder to push togehter), or having contacts back out of the plug (with non-waterproof connectors)
Wire damage at the motor axle exit. This is usually caused by the bike falling on it's side or crashing, and scraping up the wires. Sometimes it's shipping damage. It isn't always visible, but usually is. Wires can be cut or pinched, and insulation may appear undamaged but still have slits in it that allow shorting when wires are pushed against each other by cable tension or twisting or pressure, and if the system was powered on when the short happened, it can blow up motor hall sensors or controller FETs. Or wires (usually the thin ones for halls) may simply be cut or broken by the damage.
WIre twisting damage at the motor axle due to failure of torque arms to hold the motor axle still in the dropouts. If the axle is allowed to spin, it twists up the wire (usually obvious, sometiems not), which results in the same damage as the previous mode.
Motor overheating causing hall sensor failure. (or winding damage, but much rarer). Overheating is usually caused by either using a bigger controller than the motor can handle, or using the motor under too high a load for the speed it's running at, or both.
FET failure in the controller, usually from one of the other problems above.
One thing to test for phase wire shorts or FET failures (usually shorted) is to put the bike upside down, and then manually hand spin the wheel *backwards*, which bypasses the clutch and causes the motor to spin. It should have a little more resistance than spinning it forwards, but not a lot. If it is very hard to turn, or feels like it "clicks" or "cogs" with significant force repeatedly, there is probably a FET shorted or a winding or phase wire short. Unplug motor from controller, and retest. If it's the same as before, then it's in the motor or motor cable. If it's different, much less resistance, then the controller probably has blown FETs. Easier to replace than repair, but you have to find and fix the cause to prevent it happenign again.
Connections between motor and controller. Can be anything from the wiring inside the motor and controller all the way thru the connectors to inside the controller, but is usually at the connectors themselves, not being fully plugged in (common with waterproof connectors cuz they're harder to push togehter), or having contacts back out of the plug (with non-waterproof connectors)
Wire damage at the motor axle exit. This is usually caused by the bike falling on it's side or crashing, and scraping up the wires. Sometimes it's shipping damage. It isn't always visible, but usually is. Wires can be cut or pinched, and insulation may appear undamaged but still have slits in it that allow shorting when wires are pushed against each other by cable tension or twisting or pressure, and if the system was powered on when the short happened, it can blow up motor hall sensors or controller FETs. Or wires (usually the thin ones for halls) may simply be cut or broken by the damage.
WIre twisting damage at the motor axle due to failure of torque arms to hold the motor axle still in the dropouts. If the axle is allowed to spin, it twists up the wire (usually obvious, sometiems not), which results in the same damage as the previous mode.
Motor overheating causing hall sensor failure. (or winding damage, but much rarer). Overheating is usually caused by either using a bigger controller than the motor can handle, or using the motor under too high a load for the speed it's running at, or both.
FET failure in the controller, usually from one of the other problems above.
One thing to test for phase wire shorts or FET failures (usually shorted) is to put the bike upside down, and then manually hand spin the wheel *backwards*, which bypasses the clutch and causes the motor to spin. It should have a little more resistance than spinning it forwards, but not a lot. If it is very hard to turn, or feels like it "clicks" or "cogs" with significant force repeatedly, there is probably a FET shorted or a winding or phase wire short. Unplug motor from controller, and retest. If it's the same as before, then it's in the motor or motor cable. If it's different, much less resistance, then the controller probably has blown FETs. Easier to replace than repair, but you have to find and fix the cause to prevent it happenign again.
And what do the suggested tests reveal?
999zip999
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