http://live.pirillo.com/ – How to you know which one of your batteries has power – and which one doesn’t? Why, with a battery checker, of course! A battery tester is a small device that lets you see how much charge is left inside your battery. Models vary in size and usability, but most of the popular testers will allow you to check AA and AAA batteries, while the high end models will support everything from AAA all the way up to C and D batteries.

You simply plug the battery in and the built-in indicator tells you a good estimate of how much juice is left.

So, what do you use to determine how much battery life you have left?