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Controlling the speed of a 12/24V 100W DC motor? Answered

Hi all,

I have been given a 24v DC 100W old scooter motor and one 12v battery (the other 12v battery died).

I'd like to be able to control the speed of the motor and have been told I would need a PWM. I have found a PWM on ebay which says that it's a PWM HHO RC Controller, 12V 30A.

Would this one be sufficient to slow the motor to say 10-20 RPM and back up to full speed?

Thanks in advance.


Well, it would, but you won't get 100W out of it.

Hi, thanks for replying.
What would that mean to me exactly? That it would work but run slow? When I connect it directly to the 12V battery it spins VERY fast - I don't need it to spin anything like as fast as it does, 100 RPM would be max for what I need it for (if that!).

Then use belts and pulleys, not a speed controller. What FINAL speed do you want ? Its odds-on that the motor you have will be running at 3-4000 RPM.


I still need to be able to control the speed, but I'd ideally like to go from 0-(around)100 RPM.

That's fine, you can use a speed controller, but you need to transform the speed using a gearbox/chains/pulleys


To resurrect old thread: How would you make this 24V 100w motor geerate to charge a 12v leisure battery using a bike turbo trainer?