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4.4:1 Metal Gearmotor 25Dx63L mm - Low Speed Operation

I am having trouble running this gearmotor at low speed. Even with nothing connected to the output shaft, I see the following behavior. Note that for testing I am using my benchtop power supply directly connected to the motor:

  1. As I raise the voltage from 0V, the motor does not start turing until I’ve reached a voltage of 1.8V. Current rises to 1.68A until the motor starts turning and then drops down to 0.22A.
  2. Once the motor is turning, I can decrease the voltage down to 0.5V before the motor stops turning.

Is this normal behavior?

Thanks,
Michael

Hello, Michael.

That behavior does not sound unusual. Most motors require a noticeably higher voltage and draw more current to get started since they need to overcome their own internal static friction and cogging torque. Running motors at low speeds well usually requires velocity feedback and closed-loop control, such as encoders or tachometers and PID control, though even with that it can still be challenging. Using a gearmotor with a higher gear ratio can make it easier to run operate at low speeds at the cost of reducing your maximum achievable speed.

- Patrick