I've been using a 28BYJ-48 5V stepper motor in a little project for a pan-tilt camera system, where the stepper is the pan motor. I'm powering it with 6 AAA NiMH batteries in series so it's about ~7.5-8V supplied. I'm using an Arduino Pro Micro (ATMega32u4).
I've noticed that upon startup (where I am turning on the pins on the microcontroller and buffered via a ULN2003 IC), the stepper motor refuses to turn. After about a minute, the stepper will start move in small jerks in the direction I am telling it to move and then by the 2 minute mark, it will be turning smoothly as it should be.
Are there any interesting points about steppers that I do not know about regarding startup issues? Have any of you seen this before? (Sorry in advance, I understand this is extremely vague and too many variables, but I'm not sure if it's a common issue because I don't work with motors usually)
I've been wondering if it has to do with the extremely poor ventilation around the stepper because I pack a bunch of other wires around it and the bottom of the stepper is hot-glued to a base (instead of using the mounting flanges). Or perhaps the wires around it are adding to some overall magnetic flux imbalance (seems unlikely as they are mostly low-current signal wires, not power wires, and nothing is more than 1A draw in the system).