My Macbook Pro is still going strong in it’s second year. Something I have noticed though is that while the battery life is still very good and hasn’t really deteriorated, the reporting of battery capacity has become a bit erratic. On start-up it will say there’s an hour left but after half an hour it will then say there is 2.5 hours remaining. There’s also been a couple of times when there’s been at least an hour left for it to conk out within five minutes. This wasn’t down to capacity but misreporting what charge was remaining. Help is at hand though.
I found a document on Apple’s site that explained how to calibrate your Mac’s battery. It turns out that each battery has a microprocessor that works out how much juice is remaining. However this needs calibrating from time to time to keep your on-screen battery indicator accurate. I ran through the steps a few days ago and I now have a happy battery icon again. Joy. Might be worth running through the steps if your having similar hiccups on your Mac.