Most battery-life extending pack tend to be brain dead, they automatically charge when they're the needed. The Wi.U is a bit different. You can set the date, time and percentage you want the charger to activate.
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Source: http://feeds.gawker.com/~r/gizmodo/full/~3/VSS7KKRPhY4/heres-a-wireless-iphone-battery-pack-that-you-can-program
LEVEL 3 COMMUNICATIONS LAWSON SOFTWARE LAND SOFTWARE LAM RESEARCH
