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?
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.
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.
