I got this little car I built using two of these motors and A4988 drivers.
It was running with a 12V power supply, but I'm trying to get it on a battery and running for about 8 hours. thought I could use one of those phone power banks that give 5V,
but I tried using a 5V power supply and it doesn't seem to work.
Thought maybe 5V is not enough for the driver, but they say here that it should do:
Can I drive a low voltage stepper motor with an A4988 driver?
Any idea what the problem could be? (I'm also open for other solutions)
By the way, don't know if it matters but the power also goes to the Arduino controlling the thing.
Best Answer
The answer to the question you linked to explains that a 2.55V rated motor could work with the A4988 driver.
Answers continue on to explain the real constraint for a stepper is thermal, it could be 'cooked to death' by too much power.
The answers also explain the A4988 can be set to limit the current, so that a 2.55V stepper could be driven from a 8-35V power supply without damage.
The problem is trying to drive the A4988 with 5V, as Tut wrote, the A4988 minimum drive is 8V.
Looking at Allegro's web site for Bipolar Stepper Motor Drivers the A4980 is designed to operate at 3.3V or above.
I do not read Chinese, and I can not find any mention of the rated voltage of the stepper you linked to.
It looks like the motor could be made to turn at 5V. However getting that stepper to work reliably, with sufficient torque, at a high enough speed for your purpose, might be a problem at 5V. I would try a higher voltage than 5V, maybe 8.4V of NiMh, as an experiment, using the A48988 drivers. (Edit: 7 x 1.2V NiMh is 8.4V not 8.6V corrected)
The current consumption of a motor is highly variable. In the absence of a datasheet, a reasonable guess is half-max speed is maximum efficiency, and happens around 1/2 maximum current.
One 0.45A motor might consume 0.225A if it is running at maximum efficiency, and so 8 hours would be 1.8Ah.
The maximum current is 0.45A, so one motor running at maximum current (and hence maximum power) would consume 8*0.45A = 3.6Ah.
Choose a battery, for each motor, in between those two.
The Remote Control model approach is to use LiPo batteries, which run at a nominal 7.4V (for 2 cells in series) or 11.1V for 3 cells in series. They are light, and can charge quickly. They need a LiPo charger, and they must never, ever be run too low.
(Have you access to any test equipment, for example a bench PSU which would let you 'dial in' the voltage and current?)