Best power source for robot

Hi all.
I am looking to build a robot with four 3v-6v motors, four HC-SR04s, two micro servo and an arduino Mega 2560.
I’m not sure what to do about batteries.
Option 1) Nimh AAs stacking up to 7.2v, directly used to power arduino, then put through 5v reg for everything else.
Option 2) 7.2v LiPo, directly used to power arduino, then put through 5v reg for everything else.
Option 3) 5v USB power block, used to power arduino directly through 5v pin
Option 4) Any other ideas welcome.
Any advice on which of the above is better?
Thanks :slight_smile:

Any advice on which of the above is better?

From whose point of view? The battery manufacturer? The battery retailer? The battery buyer?

What is your criteria for "better"?

You need to calculate or measure average current needed to power everything. Then, knowing the battery's mAh ( or Ah ) you'll know for how long you'll be able to use your robot .

What is a "usb power block"?

My first thought was that it might be a plug-in power wall-wart for USB 5 volt output; but then I thought about it - and maybe you mean one of those USB re-chargeable battery packs...? Which is it?

If you are planning on using a 7.2 volt power source (which I think might be a smart move, to directly power the four motors), then I would connect an R/C BEC (battery eliminator circuit) that outputs a regulated 5 volts - try to get one that uses a switching regulator design (most efficient).

You could then run the servos and the Arduino from the BEC (be sure to get one that will supply enough amperage for your needs); power the Arduino thru the 5 volt pin (ie - bypass the on-board regulator).

PaulS:

Any advice on which of the above is better?

From whose point of view? The battery manufacturer? The battery retailer? The battery buyer?

What is your criteria for "better"?

I just mean in terms of everything, how many charges before it dies, charging time, weight to mAh etc as I haven't used any of these to power a bot before I'm just interested in other's advice and experience.

waski: You need to calculate or measure average current needed to power everything. Then, knowing the battery's mAh ( or Ah ) you'll know for how long you'll be able to use your robot .

Yes I am planning on doing that soon.

cr0sh: What is a "usb power block"?

My first thought was that it might be a plug-in power wall-wart for USB 5 volt output; but then I thought about it - and maybe you mean one of those USB re-chargeable battery packs...? Which is it?

If you are planning on using a 7.2 volt power source (which I think might be a smart move, to directly power the four motors), then I would connect an R/C BEC (battery eliminator circuit) that outputs a regulated 5 volts - try to get one that uses a switching regulator design (most efficient).

You could then run the servos and the Arduino from the BEC (be sure to get one that will supply enough amperage for your needs); power the Arduino thru the 5 volt pin (ie - bypass the on-board regulator).

I was indeed referring to a USB rechargeable battery pack. Since a lot of them have two USB outputs I would use one for the arduino and one for everything else.

Another factor I forgot to mention was that I have no charger (parents threw both of them away -_- ) so for the NiMH AAs and LiPo options I would have to buy a charger, and I'm building this thing on a budget!! With a USB block I could use a normal micro USB wall charger. Thanks :)

Hi all. I've just received the motors, and have hooked up a 6v AA pack and an ammeter, and got the following: Per motor: 150mA with no resistnace on the wheel 420mA with wheel on floor 900mA when wheel doesn't turn

The specifications of what the battery pack has to power have changed slightly, and are now as follows: The battery pack will have to power 4 of these motors, an arduino MEGA, a ping sensor, a servo and a small rf receiver. Any advice greatly appreciated.