TuneJuice Universal TuneJuice Universal lets you charge your MP3 player or other digital device with three available-everywhere AA batteries. Just pop three batteries into TuneJuice Universal?s sliding battery compartment and attach the charge/sync cable that came with your device. (We?ve even included a fresh set of AA batteries to get you started.) Adds up to 2.25 hours of talk time to iPhone 3GS and other USB-charging devices. A must-have for travel camping or anywhere else you might face the bleak prospect of a dead battery.