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Motor to controller (Watts)


I will try to make my self clear since english is not my first language.

I'm bilding a push trailler for my mountain bike i want to use a 24v motor from a Black&Decker cordless mower.

The is no information on the motor all i know is that there is 2 dry acid batteries 12v 17ah and the motor turn's at approx 3650 rpm.


My question: Is a 24v500w controller ok for that motor or does the controller have to be a precise match to the motor wattage?

I did some research and found that most Black & Decker 24 Volt electric lawn mowers have motors rated between 1000 and 1200 Watts.

A 24 Volt 500 Watt controller could be used with 1000 or 1200 Watt motor however it would limit the motor's power to around 500 Watts. A 24 Volt 1000 Watt controller would need be used to realize the full power of a 1000 or 1200 Watt motor.

If a 500 Watt controller was used on a 1000/1200 Watt motor it would be very important for the gear ratio between the motor and wheels to be right so the motor would be allowed to run near its top RPM on 500 Watts, otherwise the controller might overheat and burn out.

For an electric bike carrying one person the gear ratio for a 500 Watt controller should allow a 15 MPH or lower top speed when the motor is running at its highest RPM. If a 1000 Watt controller and motor was used then the top speed could be geared for a 25-30 MPH top speed.

Please let us know if you have any questions.

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