# Stepper motor voltage too low?

I'm getting started with Stepper motors and I got one on ebay, it's MINEBEA NEMA23 2.5V/1.8 AMPS 1.8DEG/STEP (model# 23LM-C045-01H). I'm a bit confused by it's low voltage. Am I reading it correctly, it's 2.5Volts?  Stepper driver that I have requires at least 8 Volts (it's Arduino with rugged motor driver shield), so is it safe to drive with motor with voltage of 9 or 12 volts?  How would one drive such motor at 2.5VDC?

2 years ago
If you divide 2.5V by 1.8A, it implies that the resistance of each phase winding is 1.38 ohms. If you drive with a higher voltage, the currents in the windings may reach levels well beyond the 1.8A rating of your motor, depending on how fast you are stepping the windings through the drive sequence.

You should be able to drive this motor with your driver if you place current limiting resistors in series with each phase, so that the 1.8A is not exceeded at the higher voltage. Calculate the resistance needed to draw 1.8A at the higher voltage, subtract the motor winding resistance, and that will give the value of the resistance you need to add in series.

You waste a lot of power using this approach, (about 75% or more in fact!).
But if you don't care about that right now, this should work and not damage your motor.
ramanm2 years ago
All stepper motor have low voltage, the higher voltage from driver is used for getting better speed. If your driver is bipolar chopper you do not need series resistance set current 1.8 amps. If you have L/R driver than you need series resistance to limit current.
steveastrouk2 years ago
It depends on your controller. The best modern ones will regulate the CURRENT to the coil, by switch mode techniques.
bratan (author)  steveastrouk2 years ago
You mean by PWM signal frequency? I think it does that. Thanks a lot!