We've now tested the Qubie prototype around the office a few times; 3 of them, actually - they all look like the one pictured below, but with a short USB cable connecting the Raspberry Pi to the battery.

In addition to gathering a lot of useful presence data for us to analyze, our testing also yielded some very encouraging battery life numbers. Using the 18500mAh battery shown in the picture below, Qubie can run for about 36 hours while providing an update every minute to a connected Bluetooth LE device. That's far more time than we'd need at a typical polling place, since polling places are usually open for between 12 and 16 hours.