18v7 Heat Sink/protection? - Simple Motor Controller

The docs for the Simple Motor Controllers suggest heat sinks, I’m wondering if that includes the 18v7 and where one would attack it? (Guessing the 8 transistors near the power connector). I may be a bit under-rated, but I probably can’t fix that in the next week.

Are there other things I can do for protection? Like if the user shoves it from full-forward to full-reverse, which probably puts an icky load on the controller. Where is it safe/recommended to fuse? What size fuse is appropriate?



We don’t have any specific recommendations for heat sinking that board. Heat sinking might be an option if you have experience with it and know what you are doing, but in general, we recommend using a controller that can handle the full current your motor might draw without a heat sink.

In your case, your other post makes it sound like your board has already been damaged, so like you pointed out, it is probably better to just get a new controller that can handle more current. We generally recommend choosing a motor controller with a continuous current rating greater than the stall current of your motor. You might take a look at our other Simple Motor Controllers to see which one is most appropriate for your motor.

Our Simple Motor Controllers have “Max. acceleration” and “Brake duration” settings that can help reduce current spikes in situations like full forward to full reverse. You can read more about these settings in the “Motor Settings” section of the Pololu Simple Motor Controller User’s Guide.

A fast blow fuse in line with one of the motor leads would probably also help to protect the motor controller. What rating you would use depends on which controller you get, and what you want the motors to do, but you might start by trying a fuse rated for somewhat below the peak current of the controller (e.g. a 20A or 25A fuse for the 18v7).


Thanks for the advise. I’ll look at a fuse. As I mentioned in the other post, it seems like the real cause was that the motor’s brushes wore out, likely due to being pushed too hard (V was at upper limit of it’s rating, I sort of forgot because it was working :P)

So the system doesn’t seem too bad, but brushes do wear out eventually anyway, so I’d be happier if there was something to help protect if they started getting nasty again. (I’m replacing with a more appropriately rated motor and a higher rated controller, but I think that normally I was well within range of the old controller.)

I also had skipped applying accel/decel values, which in hindsight wasn’t a great plan.

Thanks for the help. I’m much happier after figuring out my trouble :slight_smile:

FWIW, this is for our Lego Artoo & Mouse Droids, flickr.com/photos/120610722 … 650704775/

Artoo has much more powerful scooter motors, so I was confused that the little mouse droid was causing trouble with the smaller motor, until I remembered it was underrated…