Powering 48 stepper motors & stepper motor drivers

I hope you can help.

I’m using 48 MP6500 Stepper Motor Driver to control 48 3.9V Stepper Motor. The stepper motor drivers l1 & l2 are not connected and should be using 0.5A. There are also 8 Arduini Nano 33 Iot connected to the power supply

Unfortunately the power supply MW RSP 320 5, 5V 60A doesnt seem to be able to supply enough power.

With 47 stepper motors and stepper motor drivers connected and powered up everything seems ok. When I add the last one the system becomes unstable and the 8th Arduino doesnt have enough power.

If I start the system with none of the motors turned on and then turn them on all together, a couple of the Arduinos restart, which I presume is down to the power supply isnt able to provide power immediately. If I turn the motors on in batches the system is stable. Apart from when I add the 48th motor.

Looking through the forums its suggested to connect ground to -V on the power supply.

Please could you advise on a better power supply or things to try.


Hi, Miles.

I expect 60A to be plenty for 48 of those motors and 8 Arduino Nanos. I recommend looking at the voltage at various points on the power supply rail with an oscilloscope. Then you can see if there are any dips or large voltage drops.

I do not understand what you mean about connecting ground to -V on the power supply. Generally, all the grounds in your system should be connected. Could you post a diagram or some pictures of your connections?


Like you, I thought the power supply would be plenty.
Sadly, I dont have an oscilloscope.

The power supply has -V and +V outputs. (I’m assuming -V is ground and have connected this to all the grounds)
The power supply has a ground input, and some posts have suggested connecting this to -V


If your power supply has 3 terminals, V-, V+, and GND, you should connect your circuit to the V- and V+ terminals. You do not need to connect to the GND terminal. If you post a diagram and pictures of your connections, I can check them.


Hopefully the diagram makes sense.
I’ve attached the dir and sleep pins to 1 pin on the arduino (to reduce the amount of pins used). Each driver has 1 arduino pin for step, there are six per arduino. The arduino would then turn on all motors, set a direction and move each motor individually.
Initially the arduinos were attached to the same power supply. Over the weekend I moved them to their own separate supply. The system now seems stable. I’m guessing when the motors were turned on the arduinos werent getting enough power and would reset.

If moving the Arduinos to a new supply solved the issue, it is likely the supply voltage at their input was dropping enough to reset them as you mentioned. Thanks for letting us know you got things working!