Hey everyone. I'm new here. Can anyone help me in powering my arduino using a battery? I don't want to use 9V batteries as 45% of the power is wasted. So what aa batteries and in what combination should i use so they last long? Any other suggestions. I want a perfect 5-5.5 v voltage so no power is wasted. Thanks.
The arduino Uno is an awful device to try to run on battery. No care to power usage was taken in the design, and as such it burns over 50mA (of which only like 20mA is the '328p itself - so you can't get the power usage down much with sleep modes), and it runs on 5v, but has a lousy regulator that needs 7v to get 5v out. Plus like, battery operated things are usually supposed to be portable, and the Uno is very bulky. Uno is for learning the basics - it's lousy for integrating into a project. For rechargables, it needs a 2S LiPo battery. For primary battery, you could do a stack of
What you want to run is an 8mhz 3.3v pro mini, LiPo battery, with Vcc tied directly to the battery (or to power output if you're using a battery manager board - there are lots of cheap charging/protection controller boards for LiPo batteries available on ebay), assuming a varying operating voltage is acceptable for your application. Remove the regulator and power LED, and you've got nothing other than the '328p sucking power. When programming the pro mini, be sure to set it to 3.3v, and do not connect the 3.3v from the serial adapter to the Vcc on the pro mini.
For primary batteries, I'd use 3 AA batteries in series, and otherwise similar setup to above. They would start out at 5.2v total, and at 8mhz a '328p will keep kicking down below 2.7v (I'd set BOD to 2.7v probably).
Or instead of the pro mini's, build a standalone arduino on a piece of prototyping board, so you have nothing else to waste power, and don't have to go taking a razor and/or soldering iron to the pro mini to remove the power LED and regulator:
(That's made on the prototyping board I sell - I have a lot of varieties 
)
This guide by open electronics explains whole method: Feeding power to Arduino: the ultimate guide - Open Electronics - Open Electronics.. If you compromise the other solution is ac adapter: Arduino Playground - WhatAdapter
I want a perfect 5-5.5 v voltage so no power is wasted.
No battery supplies voltage in just that range.
To meet that requirement, some power will always be wasted by a voltage regulator.
livelongpranav:
Any other suggestions. I want a perfect 5-5.5 v voltage
Yeah, use a boost converter along with two or three primary or secondary AA batteries. You will get your "perfect" a.k.a stable 5-5.5V range.
livelongpranav:
so no power is wasted.
Arduino Uno's built in voltage regulator still wastes power, no help here.
jremington:
No battery supplies voltage in just that range.
He can use a USB power bank :
The best way to power Arduino boards is through USB port. The power bank is the easiest.