I'm planning to try to build an electric go-kart. My idea was to use a 12V starter motor from a car to power it, since used ones are fairly cheap and easy to get. (I already have 2 of them to experiment with).
I've read that starter motors aren't a good choice because they aren't meant to run continuously and will get too hot. But I was wondering if I limited the current, maybe with external resistance connected in series with the motor, will that help to prevent the motor from overheating?
Starter motors normally draw a huge amount of current in order to have enough power to crank an engine, which needs a lot of force because of the engine compression. But I figure I wouldn't need to run the motor at full power just to drive a go-kart.
Could limiting the current help with this?
I thought of several different ways, including using heater elements or even just a long coil of wire for enough resistance. Since starter motors draw about 100 amps when cranking an engine, I figured if I limited the current down to maybe 40 amps, that might work to allow the motor to run longer.
How can I limit the current to a starter motor to 40Amps?
I need a cheap, simple way to do this if possible. A PWM motor controller isn't really option because it's hard to find ones that can handle enough current, and they seem to be expensive.