I have a late 2011 MBP that I bought new in April, 2012(I'm still covered under Applecare). At the time, I recall reading the built-in battery "should" still hold up to 80% of its capacity at up to 1000 cycles. My battery is currently sitting at 661 cycles, and iStat Nano is reporting the "health" at 77%. I realize that health can fluctuate somewhat, but I'm wondering if I should pay a visit to the Apple store while I'm still under Applecare. Or, more specifically, I'm wondering if Apple replaces batteries that don't meet the 1000 cycles/80% health within the Applecare warranty period. My computer is certainly not unuseable as it is now, but I can definitely noticed the diminished capacity as compared to new, and obviously I'd prefer to have this replaced under warranty if it's eligible for replacement.