Batteries - Where, How much, Kind?

I have come to a conclusion that I need help with this haha.
I have looked around many places, from places where you can build a custom battery, to places where you buy already built batteries. Rechargeable, not rechargeable.

Let me begin by letting you know I know some knowledge of electronics, but not a lot. I understand that I want a higher mAh, and a good amount of volts. Well… What I need is about 10-20 volts.

I think I am going to run the arduino on a separate regular 9 volt battery.

Anyway back to my question.

Where to buy?
How much are we talking? I have seen a wide range of prices.
What kind should I get? I am using this for a robot, mainly to power motors. But I may use this battery for something else if I get bored of the robot.

Check your local security/low-voltage wiring supplier, and ask for “alarm batteries” which are usually 12v/3-5Ah and will run you anywhere from $5-15. Need more amps? Try a 12v/10-12Ah from an electric scooter.

Solutions for possible batteries…

Automovtive battery 12V
Lawn Mower Battery
Motorcycle Battery
Toy Car Battery (not RC cars but like small kid cars)
Electric Scooter Battery
Wheel Chair Battery
Drill Batteries (range from 6-24 volts and are rechargeable)
Alarm System Batteries
Large 9 volt box batteries
Small 9 volt vox batteries
Its pretty endless :slight_smile:

Multiple Battery solutions:
You need more voltage wire batteris + to - of identical batteries
Need more Ah wires + to + and - to - of identical batteries

An alternative for the Arduino is to feed it directly to 5V and Gnd with a 3 cell Alkaline AA battery pack. It will last far, far longer than a 9v battery, partly because of the higher capacity and partly because you’re not dissipating almost half the batteries energy as heat.

One or two downsides, you need to be careful with the polarity and its never quite at 5V, In my experience (although not the spec sheets) it will continue running down to around 3 volts with simple sensors and outputs.

Wow thanks guys!

@windhamrules

Could you wire this for more volts and ah?

  • to + and - to -
    and then
  • to - and + to -

Or would you have to create two sets of batteries with the ah connections? Then take those and wire the voltage connection?

@pluggy

Hm. Didn’t know that. Thanks, I will be careful with that then. I will probably take two/three of those then and then wire it to a 7805.

@pluggy:

Have you tried disabling the brown-out-detector to get a bit more out of the batteries? (requires changing a fuse)

The maximum safe frequency approaches 10MHz as the supply voltage approaches 2.7. Have you noticed any erratic behaviour (in the Arduino :)) as the batteries drain?

What happens when the batteries get very low? I assume the Arduino reboots because of the brown-out-detector. Is this the case?

I haven’t done too much research on what happens when the batteries get very low. The processor runs and I get sense out of the serial at around 3 volts, but I suspect it on the very edge. I haven’t run one to the bitter end so to speak. But I haven’t done anything with changing fuses or running it at anything other than 16 mHz. Alkalines will be completely knackered at 1 volt each, so I wouldn’t think it would run a great deal longer if you did get it to run at lower voltages.

If I were serious about running microcontrollers on batteries, I’d switch to Picaxe and live with the crappy BASIC programming and lower capabilities. The low end ones would run for a month or two on 3 alkalines (800 nA vs the arduino’s ~ 18mA) without resorting to sleep mode.

Could you wire this for more volts and ah?

  • to + and - to -
    and then
  • to - and + to -

You should read up on battery wiring (series vs parallel) → here are google’s top results:

http://www.google.com/search?q=battery+series+vs+parallel&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

Cool thanks for the information, that helped a lot.

Now, I am presented with the problem of recharging these batteries.
:-/