The test platform is a Palm III with OS 3.0, 2MB, with the backlight off. The test application is Atom Smash, the same app we used to test the Palm IIIc earlier this year, with the sound effects turned off. Atom Smash has an in-game battery meter that can display battery voltage, so that allows us to monitor the drop in voltage over time. We disable the auto-power-off feature of Palm OS, mainly so we don't have to press the "on" button every 3 minutes for a day and a half. We let Atom Smash run in demo mode until the unit shuts off. With auto-power-off disabled, the battery has to get down to just below 1.4 volts for the unit to go in to safe-mode power off. Notably, even after this last ditch power-off, the Palm III was still able to run for 15 to 20 minutes before shutting off again, plenty of time to HotSync and save your data. We didn't lose any data, even after abusing the batteries beyond what the average intelligent person would do. The battery life times listed in the results are the times from first turning the unit on until the first safe-mode power off.

So let's get to the point - the e² AAA performed better, but only by about 10%. By contrast, the e²s cost about 23% more. The standard Energizers lasted 18 hours, 25 minutes, while the e² s lasted 20 hours, 12 minutes.

The details of the test are interesting. Both sets of batteries started off at 2.9 volts, exactly what you would expect for two 1.5 volt batteries. Both sets dropped to around 2.6 volts within a few hours, and then steadily dwindled towards 2.0 volts, still fully usable in a Palm OS device. Standard Energizers reached 2.0 volts in 16 hours, while the e²'s held out for 18 hours before hitting the 2.0 volt mark. Then something remarkable and surprising happened. The e² s dropped from 2.0 volts to 1.4 volts in an hour and 22 minutes, while the standard Energizers took 2 hours and 3 minutes to make the same drop. Perhaps this is evidence of the different performance characteristics - the e² s stay at a higher voltage for a longer time, with a steeper drop near the end of the battery's life, while the standard Energizers taper off more slowly. Though it may seem like a steep power drop would be dangerous for a Palm OS device, it doesn't seem to be. The safe-mode power off leaves plenty of power in the batteries to keep your data around until you get to the next Target.