Even if you have no intention of building this well-executed battery meter, the results creator Denis Hennessy got from his tests of over 100 battery brands are an interesting read.
Hennessy was underwhelmed by the lack-luster information displays and packaging provided about batteries:
I needed a couple of AA batteries and found the display at the supermarket where they were all arrayed. Normally when I’m shopping in the supermarket, I tend to look at the price/kg or price/l when comparing similar products. In the case of the batteries, there was no such indicator. Fine, I thought, I’ll work it out myself. I grabbed a few different makes and scanned the packaging for some measure of their capacity. Nothing. Not a single one of the batteries had any indicator of how much energy they would provide. Instead, they all had terms like ‘PLUS’, ‘SUPER’, ‘ULTRA’ and of course had wildly differing prices. So, I decided that it was time for an experiment and bought one pack of every type I could find.
To that end he build an Arduino-driven battery meter and went on to test over 100 brands of batteries to see exactly what kind of energy they would output and for how long. Hit up the link below for a full run down of his process as well as his results.