Dc motors & matching controllers


1- I have acquired several dc motors, but ending up knowing nothing about their ratings. is there ant way to identify motor rating?

2- I am stuck with choosing the right controller / driver for a specific dc motor. would you advise on the selection criteria and if you provide a tool such as compatibility matrix among controller/driver v. motors



Hello Amr,

  1. The main specification of interest on your DC motors is the stall current at a certain voltage. One way to measure the stall current is to stall the motor, apply a voltage, and measure the current draw. This is pretty easy to do if you have access to a power supply. Since you don’t know the voltage range of your motors, you should try a low voltage. If you posted pictures or gave me more information about the motors, I might be able to give you an idea of what a good voltage range is for them.
  2. You will need a motor driver/controller that can supply a continuous current greater than the stall current of your motors at the voltage you power them at. If you use a motor driver, you will have to have something that can supply a single or possibly multiple PWMs to the driver per channel depending on the driver. Our controllers have different communication options. Most of them support a serial protocol. Some support RC servo pulses or USB. Once you have figured out more information about your motors, I can help you narrow down your controller/driver options.

- Ryan

Hello Ryan,

thank you for your reply… here is a list of motors I ordered lately from Pololu store:
1- Brushed DC Motor: 130-Size, 6V, 11.5kRPM, 800mA Stall
2- Tamiya 70168 Double Gearbox Kit

here are comments from the site on both items:
1- It has a recommended operating voltage of 3 – 12 V, at 6 V, the no-load speed is about 11,500 RPM, the no-load current is approximately 70 mA, and the stall current is around 800 mA

2- The low-voltage motors run on 3-6 volts and draw up to a few amps, making them perfect candidates for the Pololu low-voltage dual serial motor controller.

for the motors in the second item there is a link to the motor datasheet which states that its operating range is 1.5v to 3.0 v. :exclamation: :question: :angry:




I’m not sure what your point or question is regarding the first motor. For the second motor, the nominal voltage is 3V, but you can typically go over or under that, though running at higher voltages will reduce the motor life (see nexisnet’s tests for more info). Another consideration is that you usually lose some voltage in the motor driver, and if it’s not that great and your 6V battery is not totally fresh, you might not have much more than 3V at your motor, anyway.

- Jan

have a problem with my SMD with the dc Motor Controller …think it needs a overall rework. just thinking of soldering it but dont know which is most effective