Power management chips are very high on the list of components damaged by liquid, due to the large amount of power they handle, plus the fact that they're energized even when the computer is off, AND when the main battery is removed. (due to backup battery, usually very inconveniently located under optical drive or logic board)
The system that charges the battery is probably damaged and is not smart charging it anymore, leading to reduced battery life. That would be an abuse-replacement of a logic board, which is silly expensive.
Best thing you can do if that's the case is leave the main battery out when it's fully charged. Only put it in when going mobile and to recharge it. Consider yourself lucky... a LOT of them simply won't CHARGE the battery at all anymore. (or power on for that matter, more often)
