- I think the scenario you are referring to is the power potentiometer located on the stepper driver. This is a dial that controls the amount of current going to the motor (usually 30%-100%). Current is a measurement of the Ampere supplied to the motor, so if you have a 1.5A motor and a 2A driver you need to at least be below 75% to keep from frying the motor. If your buying a prebuilt you shouldn't have to worry about setting and calibrating this.