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Powering two stepper motors
Moderators: adafruit_support_bill, adafruit

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Powering two stepper motors

by MotorNoob on Sun Oct 24, 2021 7:40 am

Hey!

I'm trying to power two stepper motors using Adafruit Motorshield V2, however I'm not sure how I calculate what type of power supply I need two power them both. When I try to use a 2A 12V external power supply, the power LED and motors pulsate.

I have the following stepper motors (SL42STH34–1334A)
https://www.alibaba.com/product-detail/ ... 64248.html

Are the motors even compatible with the shield?

I'm a complete noob, so I'm grateful for any help I get! Thank you so much!

MotorNoob
 
Posts: 4
Joined: Sun Oct 24, 2021 6:35 am

Re: Powering two stepper motors

by adafruit_support_bill on Sun Oct 24, 2021 8:57 am

Unfortunately, those motors are not compatible with the shield. They have a phase resistance of just 2.1Ω, so when powered with 12v, they will try to pull about 5.7A per phase (11.4A per motor). That exceeds the current ratings for the motor, shield and power supply. The drivers on the shield are simple H-bridges and do not have current limiting. If you are lucky, the power supply was the limiting factor and prevented damage to the shield & motors.

https://learn.adafruit.com/all-about-st ... he-stepper

Motors with specs like that are designed to be used with a current-limiting 'chopper' type driver such as the DRV8833: https://www.adafruit.com/product/3297

adafruit_support_bill
 
Posts: 82405
Joined: Sat Feb 07, 2009 10:11 am

Re: Powering two stepper motors

by MotorNoob on Sun Oct 24, 2021 10:41 am

adafruit_support_bill wrote:Unfortunately, those motors are not compatible with the shield. They have a phase resistance of just 2.1Ω, so when powered with 12v, they will try to pull about 5.7A per phase (11.4A per motor). That exceeds the current ratings for the motor, shield and power supply. The drivers on the shield are simple H-bridges and do not have current limiting. If you are lucky, the power supply was the limiting factor and prevented damage to the shield & motors.

https://learn.adafruit.com/all-about-st ... he-stepper

Motors with specs like that are designed to be used with a current-limiting 'chopper' type driver such as the DRV8833: https://www.adafruit.com/product/3297


Hey Bill! Thanks for your detailed answer.

So I'm gonna buy two new motors in that case. This one seems to work if my calculations are correct.
https://www.amazon.com/Hitommy-26N-cm-S ... B07FMT8Q77

Am I correct?

I'm thinking with a twelve volt supply it should draw 12v/30Ohm = 0.4a per motor, so a power supply of 12v 1A should work, correct?

I'm new to these calculations.

MotorNoob
 
Posts: 4
Joined: Sun Oct 24, 2021 6:35 am

Re: Powering two stepper motors

by adafruit_support_bill on Sun Oct 24, 2021 10:49 am

Yes. Those motor specs are a good match for the shield.

adafruit_support_bill
 
Posts: 82405
Joined: Sat Feb 07, 2009 10:11 am

Please be positive and constructive with your questions and comments.