In other words, if the load is great enough, will a 110V, 18A rated motor being run at 5V stall at the same current as if it were run at 110V? I'm asking because I'm currently working with a treadmill, which at its lowest speed (I read ~6V across the motor free-running) has enough torque to move a large amount of weight. I measured the motor's resistance to be 0.9 Ohm, so at its lowest speed free-running the current draw is around I=V/R = 6.7A? Or is that the stall current?
Would powering the motor on its own with a 5V supply be the same as the onboard controller providing 5V to the motor through PWM 120V?
I guess I'm just surprised a motor can provide so much torque with such little voltage. So what determines a motor's current?