I originally thought this was a battery calibration issue when I first got my iP4, so I drained the battery completely and charged for 8 hours. My nightly charge routine is sync, turn off while still docked to Mac, then either close the lid to the Macbook or leave it open. Sometimes I'll wake up to 100% charged, other times it could be 80%. Is the iP4 not designed to charge when turned off and docked to a computer or is there another issue?