Powering Tamiya twin motor gearbox with 6v

I’m planning on using the Tamiya twin motor gearbox with the Baby Orangutan B-328 and powering it with 4 AA batteries (alkaline, so around 6v). However, the motors in the gearbox want 3v and I don’t see any way on the baby to access the motor power pins on the H bridge, they appear to be connected directly to the battery. I was going to use just two of the batteries or even a second power source to provide 3v to the motors, but I just don’t see any way I can do that on the baby.

I know the motors will run fine on 6v, but how long are they going to last like that? Is there any way to run them on 3v with the baby?

I may have answered my own question. I can just use a range of -128 to 128 on the set_mX_speed functions and it should be more or less the same thing.


We don’t have manufacturer specs for the lifetimes of our motors as a function of voltage, but fortunately nexisnet did some testing on the motors in those Tamiya gearboxes. You can see his results here:


According to its datasheet, the TB6612FNG motor driver on the Baby Orangutan requires a motor voltage of at least 4.5 V, but you have a few alternatives to running the motors at 3 V. One is the approach you already thought of: limit your maximum duty cycle to 50% so the average motor voltage doesn’t exceed 3 V. The other is to exchange the motors in the gearbox with a higher-voltage, lower-current replacement. These replacement motors can deliver approximately the same power as the 3V Tamiya motors, but they are generally easier to control and produce much less electrical noise.

- Ben

Thanks for the link, very informative. It looks like I definitely won’t want to run these motors at 6v. The PWM solution sounds just fine to me, but the 6v motors are cheap so I’ll probably just order a set of those as well.