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Overcoming DC motor stalling
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Please be positive and constructive with your questions and comments.

Overcoming DC motor stalling

by Braveheart_ on Sat Aug 08, 2020 4:07 pm

Hello,

I am pretty much a beginner and non-engineer or programmer. I'm using the DC & Stepper Motor HAT for RPi to control the typical (and Cheap) 4-6V TT DC motors. I can get everything working in my project, but I'm having a hard time understanding how to overcome motor stalling. Obviously different surfaces pose different friction sources. I don't expect carpet to work but ceramic tile and hardwood floor is also problematic.

I'm tank steering my four wheeled robot car, so reversing direction and overcoming friction is causing the small 6V motors to stall (drawing too much current) and stop moving.

My question is, can I bump up the voltage source to 9V for instance or am I doomed to spend more money on better 9 - 12V rated DC motors that have better torque ability to be able to move my four wheeled robot around better? What are the options?

Thanks in advance.

Braveheart_
 
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Re: Overcoming DC motor stalling

by adafruit_support_bill on Sat Aug 08, 2020 5:22 pm

What are the current ratings for your motors? Increasing the voltage will increase the current draw. The driver chips in the HAT can handle 1.2A continuous. If your motors try to pull more than that, you can damage the HAT.

www.pololu.com has a good selection of quality gearmotors with a wide range of gear ratios, voltage and current ratings.

adafruit_support_bill
 
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Re: Overcoming DC motor stalling

by Braveheart_ on Sat Aug 08, 2020 6:58 pm

Thanks for replying to my question. So it appears the answer is replacing the motors. I wish I new what the current rating is. They are just the standard yellow plastic gear motor you see in a lot of kits. Here is the exact kit I bought on Amazon.

https://www.amazon.ca/intelligent-educa ... s9dHJ1ZQ==

It does not give you much detail on the moving parts. Are you saying if I give the 6V motor a 9V power source, the current draw will be higher than the HAT rating? This also begs the question of how would I measure the current draw for a beginner? Most likely the answer is way over my head so that is more rhetorical.

Thanks for the link to the site. There is a ton of options there. I take it I'm looking for a larger motor? The HAT can take up to 15v. How does one go about figuring out the motor size they would need? Is that a typical problem or more of one with a lot of math for an engineer degree type person?

Thanks.

Braveheart_
 
Posts: 4
Joined: Sat Aug 08, 2020 3:57 pm

Re: Overcoming DC motor stalling

by Braveheart_ on Sat Aug 08, 2020 7:30 pm

This looks exactly like the motor in the kit. https://www.adafruit.com/product/3777
Is there a data sheet I can extrapolate what would happen at 9V for?

Braveheart_
 
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Re: Overcoming DC motor stalling

by adafruit_support_bill on Sat Aug 08, 2020 8:29 pm

At 6VDC we measured 160mA @ 250 RPM no-load, and 1.5 Amps when stalled

Assuming that the motors are the same, you can expect the current levels at 9v to be 150% of what they are at 6v. So if they are stalling, they are probably overloading the TB6612 drivers on the HAT. The overload protection on the driver chips good for the occasional stall. But chronic or extreme overloads will do damage.

We do have these motors which have a higher gear ratio: https://www.adafruit.com/product/3802
These will give you more torque at a lower speed for the same power input.

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Re: Overcoming DC motor stalling

by Braveheart_ on Sat Aug 08, 2020 11:54 pm

Much appreciated. Thank you. :-)

Braveheart_
 
Posts: 4
Joined: Sat Aug 08, 2020 3:57 pm

Please be positive and constructive with your questions and comments.