Erratic behaviour after 3 minutes

Hi
I am using an Arduino with a cnc shield with 2 DRV8825 to run 2 Nema stepper motors

The program is a simple 1800 steps clockwise and then 1800 steps counterclockwise. Everything works perfectly for 3 minutes . Then the movement of both motors become erratic. They don’t complete their 1800 steps, or they stop and start again in a very unpredictable manner. When I cut the power only to the motors, CNC shield with the DRV8825 for a few minutes and then restart, they work fine…for three minutes. The Arduino power is not cut nor reset.

So I am guessing it is a heat issue? The motors get warm but nothing extraordinary. The two DRV8825s get very hot. (Burn your fingers) My power source is 18 volts 10 amps.
Any ideas about what is going on?

Ok, I turned down the power output on the two DRV8825 . Now one motor runs as fine and runs cold . The other motor continues to misbehave after 3 minutes and gets medium warm. I installed another DRV8825 but no luck…So I guess it is the motor.

I re-adjusted the output on the DRV8825 and the motor is behaving correctly after 20 minutes

Hello.

It sounds like you might just be adjusting the current limit without measuring it or considering your motor’s ratings. To configure it properly, you should set the current limit by measuring the VREF voltage and setting it according to the formula on the DRV8825 carrier’s product page so that the current limit is equal to or less than the current per phase rating of your stepper motor (up to 1.5A per phase, which is what the DRV8825 can handle without additional cooling). You can find more details, including a tutorial video, under the “Current limiting” section of the product page.

Brandon