Help debug my electric scooter problem: motor has no torque

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starrychloe
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Help debug my electric scooter problem: motor has no torque

Please help me debug my electric scooter problem. The motor (48V, 500W) has no torque, but will spin when off the ground. I don't know if it is the controller or the motor, or something else.

Motor continuity, disconnected: yes, .5 ohm
Voltage at battery/controller, connected, zero to full throttle, wheels blocked: 52-42 V
Voltage at motor/controller plug, connected, wheels blocked, full throttle: 3-4.5 V slowly increasing
Voltage at motor/controller plug, connected, free wheel, low to full throttle: 5 V - 17 V
Voltage at motor/controller plug, disconnected, low throttle to high: 52.5-52.1 V
Current at motor/controller plug, disconnected: about 6 A with quarter throttle (very brief test - was afraid)

The problem happened suddenly. The scooter gave out and did not seem to run. The motor makes a whining noise when it tries on the ground and the pitch goes up as the throttle goes up. It can barely push itself, but not with any weight on it. When the wheel is in the air, it can spin fast, and goes faster and faster over time slowly. Sometimes, intermittently, it will have full power/torque. Thanks!

LinkOfHyrule
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Re: Help debug my electric scooter problem: motor has no ...

Hmm...my wild guess? It's not the motor; something's slipping. Does it have any belts or gears?

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

antiscab
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Re: Help debug my electric scooter problem: motor has no ...

check the controller to make sure the shunt resistor hasnt desoldered itself.
if the shunt resistance has increased, the controller motor side current limit will be significantly reduced, resulting in no torque, but no reduction in free-wheel speed or measured on resistance.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

MOSFETmeltdown
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Re: Help debug my electric scooter problem: motor has no ...

Hmm...

"The problem happened suddenly..." and "Sometimes, intermittently, it will have full power/torque."

Loose connection?

colin9876
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Re: Help debug my electric scooter problem: motor has no ...

Bizarly I have exacly the same problem
I just bought a micro folding 180w rear hub bike from ebay.
Its supposed to be pedal start but only gives a teeny bit of power - not even enough to keep it going on the flat.
I just assumed it was bad batteries but the supplier says they r new
where is this shunt resistor - outside or inside the controller box?

antiscab
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Last seen: 1 week 3 days ago
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Points: 1686
Re: Help debug my electric scooter problem: motor has no ...

the shunt resistor is almost always inside the controller.
it will either be on the battery input side, or the motor output side.
follow the big wires/traces, there should be component that looks like a resistor, or a bit of metal soldered across two thick traces.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

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