Stepper 28BYJ-48 is Hot at 150F, Is this Normal?

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1

I'm using the 28BYJ-48 Stepper Motor + ULN2003 Drive Board programmed with a Uno R3.
The motor is running on 12V with 10 RPM speed and running 10 rotations every 15 minutes.
The stepper motor is 150F degrees measured at its case.
The ULN2003 driver ICs measure 115F degrees.
Power is provided directly to the UNL2003 driver (not via Uno R3).
None of the power wires feel hot.
I have run it like this for 24 hours, and the system has been working fine.
The stepper motor temp doesn't seem to matter if the motor is moving or not, its always hot.
Are these stepper motor case temperatures normal?
Thanks for any insight

2

  • Please confirm your motors are 12v and not 5v.

  • When the motor is not moving turn off the current to all of the coils.

3

Yeah, probably. Stepper motors are very inefficient. Most of the power gets wasted as heat in the situation you describe.

With this type of stepper, which has a gearbox, you can switch off the current, when the motor doesn't need to move, and the motor won't slip like it would with steppers that don't have a gearbox.

Why are you using stepper motors?

4

Thank you. My mistake. The motors are 5V. The driver can take 5-12V and I didn't bother to check the motors. The motors are bad now and wont run at 5V. I tried a new motor at 5V and it works. Thanks again

5
  • When the motor is not moving turn off the current to all of the coils.
6

couple of reasons, 1 is I have no idea what Im doing and 2, the stepper motors were free and they did the job I was trying to do. As I learn ill try other types of motors no doubt.

7

can you point me to code to turn off current to coils and turn on again before the next move?

8

  • Let’s assume you are using D2, 3, 4, and D5 for motor control.

  • When you want to turn off the current to the coils, use digitalWrite( ) to make each of these outputs LOW.

9

There is one other point to stepper motors. That is your mounting material is also a heat sink. Add more aluminum mass to the mounts.

10

thank you. I will look at implementing that.

11

thats an excellent point and easy for me to implement. Thank you

12

Thanks, Larry D! I figured out how to insert the digitaWrite() to turn off the Stepper Motor current when it's not moving AND turn it back on just before it begins its next rotation. It seems the motor did not start rotating immediately, and I put a 1-second delay after turning on the motor current and before the motor was commanded to move, and that did the trick, or I'm getting all the rotation I commanded. And most importantly, the motor is drawing no current when not moving (I have a power supply with the current meter to be able to see that). thank you again

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