Apple on Wednesday released Battery Update v1.1, software which enhances PowerBook and iBook battery performance by making sure that full capacity is available.
Apparently the battery update is designed only to work with some specific models of PowerBook and iBook. Specifically, iBook (Dual USB), iBook (Late 2001), iBook (Opaque 16 VRAM), iBook (32 VRAM), iBook G4 (12-inch), PowerBook G4 (12-inch), PowerBook G4 (12-inch DVI), PowerBook G4 (15-inch FW 800), PowerBook G4 (17-inch) and PowerBook G4 (17-inch 1.33GHz).
The software is available for download through the Software Update System Preferences pane.