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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
 
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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
 
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Re: Powering two stepper motors

by heeshong on Tue Dec 07, 2021 7:21 pm

Hi,

I want to control 60 of this stepper motor(https://www.actuonix.com/S20-Stepper-Li ... p/s20-.htm) by stacking Adafruit motor shields.

Input voltage is 0-3.9VDC, max current is 0.64A, and Resistance per phase ins 6.5 Ohm.

I would like to know if these stepper motor and motor shield are compatible with each other. I know the motor shield's h-bridge is written as they run motors from 4.5VDC to 13.5 VDC, which has higher lower limit voltage than the rated voltage of my stepper motor. But if they're ok to go with, I think it would save some effort because I would be able to control 60 stepper motor with one Arduino board.

If it's possible, then I have one more question about giving external power to the motor shield. As the rated voltage of my stepper motor is around 4 VDC, giving 4VDC to the motor shield to drive the stepper motors will do the job?

Thank you

heeshong
 
Posts: 1
Joined: Tue Dec 07, 2021 4:29 pm

Re: Powering two stepper motors

by adafruit_support_bill on Tue Dec 07, 2021 9:28 pm

The TB6612B drivers on the shield are designed for 5v-12v motor power. 4.5V is the low-voltage cutoff limit.

There are other issues with driving large numbers of steppers. The combined step rate for all motors is limited by the speed of the i2c bus, so while it is possible to address 60 or more motors, the top speed will be limited if multiple motors are moving at the same time.

As the rated voltage of my stepper motor is around 4 VDC, giving 4VDC to the motor shield to drive the stepper motors will do the job?

Stepper motors draw maximum power (and generate the most heat) when stationary. The current draw and coil heating decrease as the step rate increases. The 3.9v rating represents the maximum holding current while stationary (3.9V / 6.5 Ohm - 0.6A). 4V would be marginal if stationary, but not a problem while moving.

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