I plan on using an Orangutan SVP-1284 to drive a fairly simple robot, similar in size and function to the 3pi with almost identical motors to drive the wheels.
My question is, what is the recommended battery configuration for this application? I would like to use rechargeable NiMH batteries. It looks like I could use 6 AAA batteries. But is that going to be beefy enough? Do I need to move to AA or perhaps something else?
The 3pi uses AAA cells, so if your power requirements are similar to the 3pi’s, you should be fine with AAAs. Note that the 3pi supplies its motors with a boosted 9.25V, which means the 3pi draws more current from its four batteries than an identical robot with motors powered straight off of 8 NiMH cells. For this particular situation, it seems like your decision should mainly be based on how long you want your robot to run before the batteries need to be recharged (unless there are size constraints that make smaller cells more desirable, as was the case on the 3pi). If you have room for AAs, I’d suggest using those just because you’ll get more time to play around with your robot between charges.
Thanks for the tips. I’ll see if I can get the AA battery holder to fit.
By the way, will 6 batteries be enough or do I need 8?
Also, if I run the Orangutan SVP-1284 from a benchtop power supply, what is the recommended voltage (and max current)?
The SVP input voltage should be between 6 and 13.5 V, so six NiMH cells should be okay. As they discharge, they will probably eventually fall below 6V, so you might want to watch for that and use that as an indication that it’s time to recharge if they get that low. You can use any voltage in the acceptable 6 - 13.5V range, so your decision should largely be based on how much voltage you want across your motors.
The current you need depends on the motors you are using and the voltage you are running them at. If you have two motors with a stall current of 300 mA at six volts, I’d suggest a power supply that can deliver at least an amp if you plan on running the motors at 6 V, though you could get by with less if you’re careful about how you use your motors. For example, going directly from stopped to full speed will briefly draw close to the full stall current, and going directly from full speed in one direction to full speed in the other will briefly draw close to twice the stall current. If you avoid such situations (e.g. ramp the motor speed up slowly), your motors won’t be drawing as much current.
Note that the stall current scales linearly with voltage, so motors with a 300 mA stall at 6 V will draw 450 mA at stall at 9 V.