battery powered go-kart

Hi folks, new user here. A buddy and I along with our sons, are planning on building an electric go-kart using a car starter for the motor. I have several questions as I haven't been able to locate a simple circuit for safe motor control. One option is to try and build a PWM speed control circuit but since neither one of us is an electrical engineer I would worry about what I wouldn't know about the limitations of the circuit. Option 2 is what I would like to inquire about. I seems to me that if you could set up a system where say three 6v deep cycle batteries are in a series circuit controlled by some sort of 4 position switch (off, 1 battery connected, 2 batteries connected, 3 batteries) then you could use the natural cranking amp capabilites of the batteries to control speed. Does anyone have any comments, suggestions, or especially particular batteries, motors, and/or switches to use?

I suggest a sensible approach would be to begin with the motor and work from there. What type of starter motor has been salvaged for this project?

If you're not planning on a reverse, then the grounded negative will not matter. The batteries should all be discharged at the same rate, but this presents a real switching night-mare. Put batteries in series and use PWM[ pulse width modulation ] to control speed . I had enough trouble with just two 20 A motors,but that was before AAC. Lots of luck with 200A.

A starter is not your best choice for a motor, they are rated for "intermittant duty" and will not do well when run for long periods. They are also power hungry as they produce a lot of torque, which means your battery won't last long. You might be better off using on old electric wheel chair.

bergee, I like your idea of an electric go cart. I've thought of making an electric bike using car battery and a starter. PWM is the least wasteful (in terms of energy) method of speed control, but involves some powerful electronic devices. You might ask Bernard how he was able to handle 20 amp motors. It seems to me you don't need more than 20 amps at one time anyway. I mean you want your ride to last for a little while.

'just saw some beautifull 200-600W DC motors at All Electronics, also check moving parts for gears and chain etc. Example: Cat # DCM-1501, 4 in dia, 24V , 28A, 2600 rpm, $ 24.