1500w signifies the amount of power the motor can accommodate indefinitely. Therefore, if your controller is delivering 30 amps to the motor and the battery is 48V, this is about 1440w. This probably is a good estimate of the controller output, but it would be prudent for you to find out. Looks like a direct drive motor; there are pretty bulletproof since there is only one moving part. I've had good luck with a similar motor and Luna's 52V, 10 a/h battery.