Calibrating your computer's battery for best performance You can calibrate your iBook or PowerBook computer's lithium ion battery for best performance.
The battery has an internal microprocessor that provides an estimate of the amount of energy in the battery as it charges and discharges. The battery needs to be recalibrated from time to time to keep the onscreen battery time and percent display accurate. You should perform this procedure when you first use your computer and then every few months thereafter.

1. 1. Plug the power adapter in and fully charge your computer's battery until the battery indicator lights turn off and the adapter plug ring goes from amber to green, which indicates that the battery is fully charged.
2. 2. Disconnect the power adapter and use your iBook or PowerBook. When your battery gets low, you will see the low battery warning dialog on the screen. Continue to use your computer until it goes to sleep. At that point the battery has been sufficiently drained for calibration.
3. 3. Connect the power adapter and leave it connected until the battery is fully charged again.

Tip: When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, any open files could be lost. Therefore, it is important that you find an electrical outlet and connect the adapter before the forced shutdown occurs.