This article explains how to check the power of the internal backup battery in a PowerBook computer.

The backup battery saves the PRAM and power management information on the logic board when the computer is shut down.

Checking the backup battery

1. Set the date and time.
2. Perform a Shut Down from the Apple menu or Special menu.
3. Remove the main battery and disconnect the power adaptor for 10 minutes.
4. Connect the power adaptor, insert the battery, and power on the computer.
5. If the date and time were lost the backup battery may be dead or discharged.
6. If the backup battery is rechargeable, remove any main batteries from the unit and leave the PowerBook plugged in for at least 4 hours. If discharged main batteries are installed in the computer, recharging the backup battery may take up to 48 hours to completely charge. It is okay to use it while it is charging.
7. If the backup battery appears dead or will not charge have the computer serviced.

Backup Battery Types

For additional PowerBook battery backup battery part numbers , refer to article 11751: " Macintosh Family: Batteries and Part Numbers ".