philip100:
Say, two different stepper motors has moving and holding torque that exactly suits my needs.
The difference between them (despite sizes) are Amps / resistance per winding and operating voltage.I need 3 of those motors and I'll power them from a 4S battery pack (4x18650, 16.8-11.2V, 3Ah each).
I'll drive them with Pololu DVR8825's, set to 1/8 microstepping. Holding/move ratio will be about 80/20%.
Should I choose motors with lower resistance or amperage per winding, to keep my batteries run longer?
The power drain of a stepper is I-squared-R where I is the set current and R is the winding resistance
of a single winding.
You might see a small change in power consumption when the motor moves, but to a first approximation
the power drain will be constant.
In practice the lower the power a motor uses the less powerful it will be.
Anyway if you want any sort of decent battery life, stepper motors are not the answer, they are the worst
possible choice of motor for battery operation.