This article discusses battery reconditioning for the PowerBook Duo 270c, Duo 280, and Duo 280c.

Battery reconditioning is a deep discharge of a battery to avoid "memory effect" which, over time, can reduce the battery's power capacity.

The PowerBook Duo 270c, Duo 280, and Duo 280c have a modified power system which can recondition its battery. This allows it to draw power exclusively from either the AC source or the main batteries. When you recondition the battery, the Duo disconnects external power to avoid recharging, draws power from the internal battery only, and ignores all low power level alerts, including hardware shutdown. The Duo then senses when the battery is completely exhausted and fully recharges it. The entire process should take a few hours.

During battery reconditioning, you cannot use the Duo for any other purpose. While the Duo is reconditioning its battery, it goes into a screen saver mode where a black and white battery icon moves around the screen. Note that the power adapter must be plugged in for reconditioning to work.

You should recondition your battery no more than once a month. The battery reconditioning software (located on the Disk Tools diskette) keeps track of the last reconditioning performed by checking the battery's serial number. PowerBook systems prior to the Duo 270c, Duo 280, or Duo 280c cannot use the battery reconditioning software.

Please note that the Battery Reconditioning software is not on the system diskettes that come with the PowerBook Duo. You should make a backup of your software or download the software from one of the online services.

After installing Mac OS 7.6, when trying to recondition the battery in your PowerBook Duo 280 or 280c, you may get a message saying "Your battery was not reconditioned because the application quit" or "Battery Recondition will not work with this PowerBook".

Mac OS 7.6 installs version 1.5 of the Battery Recondition application which works with PowerBook Duo computers. On a PowerBook 280 or 280c, Battery Recondition 1.5 may fail to recondition the battery, producing one of the errors mentioned above. If you want to recondition the battery, follow these steps:

1. Open the Preferences folder inside the System Folder.
2. Drag the "Battery Recondition Preferences" file to the trash.
3. Restart.
4. Run an older version of the Battery Recondition application.