When you operate on battery power it’s nice to be able to track how much life you have drained from you power source. I have tested a couple of meters that measure Volts, Amps, Watts, and Amp Hours.  The first meter is the WattsUP meter version 2, the second is an import meter called the 2-Meter. I purchased both form Amazon The Watts up is $50 and the 2-Meter is $20.

The Watts UP meter

2-Meter

More review info to come later..