I have a 2 months old macbook plastic unibody version. So far I've done two calibrations, draining the battery until it shuts down itself and charging it until it reaches 100%. After the first calibration, the battery capacity dropped around 100 mAh from 5300 to 5200. Just after yesterday's calibration, the battery capacity dropped another 100 mAh or so to around 5100 mAh. The battery capacity also increases by small amounts from time to time during regular uses. Now my battery is at 94% health with 16 charge cycles. Why is calibration killing my battery?