Does the 5300 have an internal (PRAM or clock) battery?
Yes. The 5300 takes a pair or VL2330 coin-type 3V lithium rechargeable batteries wired in series. The batteries are connected to the PowerBook via a three wire cable that plugs into the Power Management Unit. The batteries are rechargeable and generally have a lifespan of several years. As long as you plug in your PowerBook from time to time, it is unlikely that the battery will go dead due to being completely discharged.