PRAM Battery For PowerBook G4 "Titanium" Models
Is your PowerBook G4 "Titanium" 400MHz/500MHz forgetting what time and day it is?
Your clock battery is failing! Time to replace it!
Macintosh computers contain an internal backup battery to maintain system settings, such as the date and time, when the computer is turned off . The battery may last up to five years though actual life is determined by shelf life of the battery and usage patterns of the computer.
When the computer does not retain PRAM settings (such as the date and time) after it has been turned off, this generally indicates a dead battery.