Hello MR, Long story short, I recently rediscovered my first computer (well, technically, second after an old, old beige Mac), a 15" hi-res PowerBook G4. It was predictably in pretty bad shape electronically (though aesthetically perfect except a minor corner dent) and I've been slowly and carefully rebuilding it. I replaced some parts like the fans (redid the thermal paste too.. the factory job was embarrassing bad), cleaned up the internals and dust, got a cheapo aftermarket battery, maxed the RAM, and have a PATA SSD coming soon in the mail. The last thing though is the dead PRAM battery. I was wondering if someone with more knowledge than I have could tell me if a PRAM battery from another model can be used with this one (mine is the A1138 model). Spares for my particular model seem to be inordinately expensive compared to previous ones... Alternately, I am considering just replacing the actual battery itself on the circuit board. The main difference seems to be that with this final revision, Apple changed the design and layout of the PRAM battery circuit so instead of a circle battery, its some kind of rectangular packet. Does anyone know what kind of battery (or a compatible substitute) could be used? Much thanks.