I have battery power (9v) for stepper motor (auto-tracker for telescope mount). I need micro stepping and high torque (0.1 N*m). I decided to use bipolar stepper and A4988 because there are cheap modules from eBay.
But: I need to rotate stepper very slowly (about 1 step per second), so most of time the motor stay without rotation and A4988 produce a holding current, but I need no holding torque (there are no external torque that can rotate my motor).
How to maximize battery life in my case. Maybe just set "enable" pin of A4988 to 1 between rotations? But I have another questions in this case:
1) Can I lost steps if I will set enable pin to 1 between every steps? In data sheet there is note that if I will use sleep pin, then after wake up A4988 go to HOME state, so I will lost steps. But there are no notes about behavior of enable pin.
2) How microcontroller can know when step have executed (before set enable pin to 1)?
Maybe there are another solutions. I need at least 5 hours of 9v alkaline battery, 0.1 N*m, single step each second.