67:1 Metal Gearmotor 37Dx57L and 14.4V NiMH Battery

Hi guys!

The Pololu 67:1 gearmotor 37Dx57L ( pololu.com/catalog/product/708 ).

I suppose I would need a step-down voltage regulator to be connected between the battery and motors to get 12V from 14.4V… If so, what regulator’s output current requirements are for my case? Can I use Pololu Step-Down Voltage Regulator D24V6AHV ( pololu.com/catalog/product/2104 ) with maximal output current of 600mA? If not, could you please refer me to appropriate product or schematics? Or there is other way to follow?

Thank you very much!


Hello, Igor.

It should be fine for you to run the motors directly off of your 14.4 V batteries; in general, DC motors can be safely operated over a somewhat wide voltage range, though higher voltages tend to decrease motor life. Regulating motor voltage is difficult and potentially expensive, especially for higher-current motors like the ones you are using, so that is not an approach I would recommend. If you are really concerned with keeping the motor voltage below 12 V, you could always just limit the maximum duty cycle of your motor drivers in software to something like 80%.

My bigger concern is with your use of the VNH2SP30 motor drivers. These drivers have over-voltage shutoff thresholds that can be as low as 16 V, and your battery pack can easily be above this threshold when fully charged. If you run into trouble with this, you might consider using our dual VNH5019 carrier, which can deliver approximately the same current as the VNH2 but operates up to 24 V.

- Ben

Hello Ben!

Thank you very much for your advice and tips. I will follow them. Have a nice day!