Apple has released a new Battery Update for the 15" Aluminium PowerBook.
This battery firmware update is required for PowerBook G4 (15-inch Double-Layer SD) computers. You will find instructions below on how to determine if your PowerBook requires this update. This firmware update is required to keep your battery life up to specification, may recover battery life in some batteries that have developed short run times, and in some cases can recover batteries that are not recognized by the system.