is my macbook battery dying/spoilt/gonna explode?

[sbojevets]

i use my macbook at home, always on ac power with battery fitted in. its always fully charge. well suddenly my battery icon started to display ' calculating ' and soon after it showed the time left to a full charge.

thing is i never unplugged, neither was there a power outage. so now my battery is showing is 90+% with 0:31 to go to a full charge, and my magsafe is displaying a orange light.

is my battery dying or is there something i do not know ?

[scienide09]

To maintain battery health, you're Mac's battery will slowly drain from a full charge down to some level (usually about 95%), and then recharge. Hence showing less than 100% and the fact that you're charging.

That you never run off the battery and always have an AC connection suggests to me that you never calibrate your battery, either.
http://support.apple.com/kb/HT1490