It sucks I know but the battery is caput! I looked into this heavily as my compaq e500 battery died recently. modern laptop batterys have power management on board and so you can even take em apart and swap the cells because it's there to prevent you. A laptop battery has a lifespan of about 18 months:( and btw your not supposed to keep it fully charged!?!
ok if I were you I'd buy a compatible (non oem) battery from ebay as the price difference is massive. ok my replacement battery from compaq will cost an amazing £120 quid but for a compatible from ebay £50 quid woohoo sod compaq have a look ebay may have yours!
Charles Woodward, July 2004