Will An Hbridge Ok To Run This Small Dc Motor On The V4 With 12v?


Finishing up my BB-8 build and looking to reduce costs by avoiding high priced motor controllers. I have 3 of the following 12v dc motors in the build. Will a standard h-bridge be enough to run them?

dc motors


Max. Stall Current: 20A @ 12VDC

It depends on how close you get to this rating. 2 will be connected to the H-Bridge at one time, meaning the rating on the H-Bridge should be a minimum of 40A @ 12VDC. Without knowing how many amps your motors are drawing when it use, it is hard to tell.

If you are drawing 2 amps from each motor, the max rating at stall doesn't really matter and a smaller H-Bridge can be used, but without knowing how many amps you are using, it is impossible to help very much.


Adding onto what Dave said, typically, you take the max rating at stall of a motor, and add some overhead and that is how you pick your H-Bridge. So in this case, 2 Sabertooth 2x25's (and you will have the ability to drive one additional motor), or 3 Parallax HB-25's (1 for each motor, and you save a little bit since the HB-25's are a little under 1/2 the cost of a Sabertooth 2x25 and you only need 3) would be decent choices.

This is assuming you don't need position feedback. If you do, then Sabertooth with Kangaroos or Roboclaws (which are more expensive but have the Kangaroo function built in) are good choices.

If you use an H-Bridge that is under the stall rating for a motor, it is pretty easy to burn it out. But, 2-amp controllers are cheap, so if you are really sure you will not be going above 2 amps then just have some spares and make your design so that they are easily accessible and can be easily swapped out.



Ok thats great info. So whats the easiest (for dummies) to figure the amps needed.



With motors as high of torque as the ones you mentioned, I would look at using a vise to hold the motor for the stall test. I would suspect that you are getting nowhere near the stall torque of these motors. I would think that you are probably in the 5 amp or lower range under load per motor, but the only way to know for sure is to test.