# Self balancing robot issue

I would like your advice on something. So I’m using 2 stepper motors (nema17) along with a motor driver each (drv8825) for my project. The rated current of the stepper is 1.3A and the max operating current of the driver is 2A.

The motor driver has a pot that allows you to change the current limit. Current limit = V * 2. So if I want 1A, then I have to set the pot to 0.5V.

When I connect my power supply to one motor, it runs smoothly. However, when both motors are connected to the supply, one starts to hum and moves very slow and the other continues to move at a decent speed that I require. Please can you help me out.

Does your power supply show you how much current is being drawn?
After you plug both in, and one moves slowly, take that motor off it’s motor driver, and connect it to the other driver that is moving fast (swap the motors to connect to the other driver). This will let you know if the problem is attached to the motor or the driver.

Hi Jacob.

Thanks for the advice. My power supply doesn’t but I built it and it’s rated at 1A.

I will try that out and inform you thanks.

Regards

Darshal

If you are connecting two motors that draw 1A each, then you are drawing 2A total, exceeding your power supply specification.

Meaning that I need a more powerful power supply right?

correct.

Thanks so much! Also, a quick one, how much current would I need, given the specs of the driver and motor?

Regards

D

`[power supply rating]` >= `[the number of motors that you connect]` x `[the current limit that you set on the motors]`

Thank you Jacob.
I have sorted the issue out.

I have a plastic wheel and the stepper motor’s shaft just about fits into the wheel. I want the wheel to be aligned and also want the wheel not to be permanently fixed to the shaft.

How do I align the wheel and how do I make it such that it’s always detachable when not in use?

Regards

D