Selecting Proper Capacitors and Current Limits

Hello Forum,

This is the first time writing on this Forum. I am about to make a first purchase on Pololu. The Item I have questions about is the Pololu Simple High-Power Motor Controller 24v23. I understand that the max continuous current current draw is 23A. The motor I am using has a resistance of .4 Ohms on the windings, which would mean that the stall current at 24 V would be similar to 60 amps. How well does the motor controller handle peak currents? under typical conditions the motor will only draw about 3 amps at 24V so should the controller handle the draw if I am careful and ramp the speed? I am also wondering what is the value of the capacitor that comes with the motor controller and how should I calculate an appropriate size value for the controller.


The SMC 24v23 should handle that motor just fine as long as you keep the continuous current in the range the controller can handle and limit the duration of current spikes that are significantly above the continuous rating (the controller can tolerate quick transient currents in excess of 100 A). If you use the controller’s built-in acceleration-limiting and don’t have a heavy load on your motors, I don’t expect you to have any trouble.

The included power capacitor is 100 uF and should be sufficient in typical applications. Unfortunately, there is no simple calculation for determining the appropriate capacitance for a particular application, however, since it depends on all kinds of things, such as the wires and power supply. In general, more is better, and you can look at the power line with a scope to see how bad it is. Also, how bad is acceptable will depend on the rest of your system.

- Ben