Making an Arduino-based robot with motor controller shield - what's the best battery(s) to use?

I have this robot I'm trying to make, but can't seem to solve one problem.  I have an Arduino Uno clone with a Rugged Circuits Motor Driver shield, hooked up to a Tamiya Dual Motor Gearbox with the two motors it came with.   The Motor Driver requires at least 8V to operate, but the motors are designed for 4-5V.  (I'm not sure if having two such motors together means you need 8-10V, but I assume not) .  I figure I can use the PWM of the outputs to only run the motors at 25%, to keep them from harm(?)

I tried at first using a 9V battery to supply it, but the current was way too low.  I figure I can either use 6 AA batteries in series, or get a ~9.6V rechargeable RC car type battery.  The Arduino is powered by a separate 9V battery.

It's a simple setup so I'll just describe it here;
-[battery] goes into the 8-30V input on the motor controller.   
-two sets of +/- wires go from the motor controller's 'Motor A' slot to the left motor and 'Motor B' to the right motor, separately
-the motors are hooked up to 58:1 gearboxes and turn 5cm rubber wheels, for differential drive.

Seems like I might have chosen the wrong motor controller shield for the motors, but if I can make it work somehow, then I will.

Any suggestions?

iceng5 years ago
Only one problem, how nice :-)
Good assumptions,
I don't know your motor loaded current
As long as brush arcing is not excessive the only
damage to motors is from overheating.
As you said the controller expects at least 8 VDC..
and 6 batteries in series does start with 9 VDC.
You may want to use C batteries (more current).

pecker5 years ago
I'm getting good results with batteries from here:
Using 6 aa batteries with two Lego medium motors and a panning servo
with the Adafruit motor shield.