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Topic: [HELP] Powering a stepper motor with a battery (Read 2223 times) previous topic - next topic

Ronbabious

Hello there!
I'm doing an arduino project where I use a stepper motor SM42HT38-1684AC it's connected to a L298N driver. I'm trying to power it with a battery, according to the stepper motors datasheet it should need 3V and 1.6A. I used 3x3.7v 1400mAh connected in parallel, but literally nothing happens when I power the stepper. When the stepper is connected to a wall adapter it runs just as it is supposed to. Anyone have an idea of what could be wrong?

Robin2

#1
Dec 01, 2018, 09:27 am Last Edit: Dec 01, 2018, 09:31 am by Robin2
A low impedance stepper motor like that is not suitable for driving with an L298. You need a specialized stepper driver like a Pololu DRV8825.

Also the motor is not intended to be driven at 3v. 12v or 24v would be more appropriate. The specialized stepper drivers can be adjusted to limit the current to protect the motor.

And, stepper motors are very inefficient so are most unsuited to power from batteries. They draw full current even when stationary.

What is the project you want to create? Maybe there is a better option.

...R
Stepper Motor Basics
Simple Stepper Code
Two or three hours spent thinking and reading documentation solves most programming problems.

Ronbabious

Thanks for replying Robin
The project is a ping pong ball shooter and is for a course I'm taking. I'm using the stepper to pull back a hammer of sorts that locks in place at a certain position and is then released to 'kick' the pong ball. At my first attempt, I tried using a step-up converter to step the batteries up to 12v, since the wall adapter I was using had an output of 12v and 1A and worked fine. But after having no luck, I looked up the datasheet and read that I took 3v, figured I'd try to remove the step up, but that didn't work either.

I am aware the batteries aren't suited for stepper motors, but since this project only needs to work with batteries for a short demo, I thought it would be fine.

Hope this clarification can assist.

jremington

Quote
I thought it would be fine.
Obviously, it is not.

Use the wall adapter for the demo, and you are all done.

Robin2

I'm using the stepper to pull back a hammer of sorts that locks in place at a certain position and is then released to 'kick' the pong ball.
I suspect a geared DC motor would be more suited to that. Maybe something like the Pololu micro-gear motors which are widely available at much lower prices. There is also a widely available gearmotor in a plastic housing which has a bigger DC motor.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MorganS

You realize that the L298N drops a lot of volts? Powering it at 3V leaves basically zero for the output. Everything is lost in the inefficiency of that driver.

You need a proper stepper driver like the DRV8825 and you need to power it with a voltage much higher than the stepper's nominal voltage. 12V is good for most purposes but higher is better.
"The problem is in the code you didn't post."

MarkT

Usually the notion of "battery" and "stepper motor" in the same sentence is a warning.

Steppers are _considerably_ more power hungry than alternatives, and consume power
constantly (not just when under load).  If you don't need easy position holding or
open-loop position control, a stepper is the wrong answer.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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