DIY Electric Car Forums banner

Alternative to Buying a Controller?

9117 Views 16 Replies 9 Participants Last post by  pyroboy1080
I'm looking for a way to make a cheap and easy to build (by theory) controller.

I've poked around on the forums and really liked the idea of the mechanical PWM controller (
) but it looks like there are too many limitations for an EV application.

This sounds like a dumb question to me, but what the heck. Is there any reason why I can't just put a large potentiometer in series with the batteries and the motor and use that as my throttle to control the power output?

Have there been any other feasible attempts to build a simple (DC motor only) controller for EV applications?

My specialty is ME, not EE so try to explain it in a way that will make sense to me! :D
1 - 3 of 3 Posts

· Registered
308 Posts
With the right motor you can control it with just a potentiometer and a contactor. Using a sepex motor you can control the field with a potentiometer and just connect the armature to the pack, via contactor.

The field power is just a few percent of the propulsion power so the losses in the pot are acceptable, you still need a sizable pot though, (rheostat).

With full field power (low pot resistance) the motor will spin very slowly, to speed it up- reduce the field power.

With a series motor, the power losses in the pot would be too great to deal with.
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.