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Power necessary to use a stepper motor


I am not experienced in the electronics field so I hope I can as a (maybe) stupid question.
I am using a Nema8 stepper motor and got it running with a DRV8825 Stepper Motor Driver. What I would like to do is to use several motors and now I want to find out, what power source will be necessary.
For the driver it is given that the motor power supply should be in the range of 8.2 and 45V. The motor will use 0.6A per coil and the rated voltage is 3.9V.
If I use the motor with e.g. 12V connected to the pins of the driver, will this be the voltage, the motor will use as well? And can I take this voltage to calculate the power which will be necessary as a power supply?
Best regards,


The “rated voltage” of a stepper motor doesn’t mean much. What does matter is the rated current, which should not be exceeded. Controlling that current is one of the functions of the motor driver. Be sure to set the current limit properly.

The motor power supply voltage has to be consistent with the motor driver requirements. The higher the voltage, the more responsive the motor.

The average motor power supply current will depend on the voltage and driver settings, and is not easy to calculate. But to be safe, choose a power supply that can supply twice the rated winding current (in your case that would be 1.2 Amperes).


Thanks for your reply!
Of course I made sure not to exceed the 0.6 A the motor can tolerate :wink:
But as my motor has two coils and I would want to ensure 1.2 A per coil, I would need a power supply of 2.4 A, right? And if I would want to run several motors I would even need this current times the number of motors. Is that correct?


Your post is contradictory. What is the rated motor current?

Please identify the exact motor your have, and post a link to the product page or data sheet.


This is the motor I use: https://www.pololu.com/product/1204
It has a rated current of 0.6A. The 1.2 A was about your suggestion to choose a power supply of twice the rated currend. Or did you already suggest this because of the two coils?
Thanks and regards!