150:1 HP micro gearmotors power consumption?

OK, I will try and explain this as best I can. Here goes…
I have two high power micro metal gearmotors, I am running them straight off a 4 AA, 6v power supply. They are being driven by a L293DNE motor driver IC, for now. I will upgrade the driver IC to a SN754410NE, once my prototype is complete. My question is this. Running these motors on a 6v power supply is basically giving each motor 3v, correct? If I set up an LM317, to deliver 6v to the same circuit will the motors still be operating off of 3v or will they each be pulling 6v? This is all assuming that both motors are running at the same speed and direction. How would I go about giving each motor 6v~8v continuous power? Two LM317’s? How is it done on the 3PI bot? Thanks for any help in advance. Sorry for the dumb question.

In a wire, the voltage is essentially the same everywhere. If you connect two 6V motors (in parallel) to one 6V battery or to the same two terminals of a motor driver, then both motors are independent and “see” 6V. Each motor will draw current proportional to the load on the motor.

If one or both motors draws a lot of current, for example if one is stalled, then the battery voltage may drop. In that case, both motors “see” the reduced battery voltage.

It is generally not a good idea to connect motors in series, but it is very instructive to do so as an experiment and see what happens. If the motors are small, experiment with stopping one motor, or spinning it with your fingers, and look to see how the other motor responds.


The 3pi uses a TB6612FNG dual motor driver to independently power each motor. Each channel of the driver is powered in parallel from the boosted 9.25V power supply, so each channel sees the full supply voltage.

- Jeremy