I am using 6 1.5v AA batteries to power the stepper motor. The 6 batteries are only used to power the stepper motor. This is how I wired everything up:
I use the custom stepper library from the following link:
The 6 batteries were empty after about an hour of the motor rotating at 10rpm. Is this normal? Seems very fast to me.
Is there a way to calculate how long the battery will last?
Is this normal?
Yes.
To calculate how long (in hours) the batteries will last, divide their capacity (in mAh) by the current draw (mA).
The motor is normally rated at 5V and 70 ohms, so each winding will take 70mA with one
winding active, 140mA with two (some step patterns like full-wave do this).
At 9V supply those values will be 130mA and 260mA instead, and you will overdrive the motor.
The first thing to do is use just 3 or 4 batteries, not 6, for the motor, that will extend life by a
factor of two-ish.
Secondly find out which step pattern is being used and change to wave drive if not already,
which is the least power-hungry.
Stepper motors are never a good choice for battery power, they take lots of power even
when stationary.
I know this is a zombie thread but...
The 28BYJ-48 is a very highly geared and its almost impossible to drive it backwards (without damaging the gears), if driven in single-step mode it is possible to use pulsed drive which massively reduces the average current requirement as they don't have to be driven when stationary.
For applications that just run for a brief time to set a position 9V should work very well, especially if some adjustments are very small and plenty of torque is needed.
I agree stepper motors are too greedy for this set-up. Did you get it all worked out?
john@better tools toolinspector.com
