Your favorite device is running low on juice and needs a couple new AA batteries—and with a quickness. You run to the store and grab the first pack of AAs you see. But should you? There's tons of options available, so which make and model gives you the most power per dollar?
Denis Hennessy had this same question when he went to his local supermarket to snag some. The one thing every brand of battery had was lack of information. Plus? Super? Ultra? What does that mean? Why aren't there any stats on their actual capacity? Enter Arduino.
Hennessy bought samples of every disposable AA battery he could find, then built his DIY battery tester with an Arduino, LCD panel, digital thermometer, stripboard, USB cable, and some resistors and wire. The circuit fully discharged each battery, while measuring its voltage and how much energy it produced in joules and watt-hours on a fixed load, until it drops to an unusable state.
He measured and compared 10 different brands of alkaline batteries. If you want to see which brands came out on top, check out his full article on his blog. You can also grab the schematic, source code, and the full results, in case you want to try it out yourself and compare. Make sure to check out the comments there for some interesting questions about the accuracy of this test.
All photos by Denis Hennessy