Yesterday I noticed a service battery warning when I clicked the drop down on my 2011 MacBook Pro. Apple puts this message there to indicate that your battery can now charge to less than 80% of its initial capacity. In my case I last replaced this battery on May 11, 2013. So it has been 649 days. Apple has rated its battery to last for about 1000 charge cycles but this one has only lasted for 434. The new battery made it barely two years after the previous battery lasted nearly the same amount of time. I am not convinced Apple’s battery life estimates are accurate.
However one thing Apple does not mention on their support pages is it may be best to keep your battery cycling each day. The ideal battery user is someone who charges their gadget overnight and then uses it during the day. Abusing your battery shortens its life. Apparently Apple batteries are very finicky about being cycled in this manner. I am still able to use my computer without issue and the battery will last for a couple hours, but I certainly do not get the battery life I used to.1
The computer was sold as having a 7 hour battery life. New batteries are rated at 5800mAh. So the 4300 mAh figure is about a 25% reduction in capacity, so even when it was new I was barely reaching 5 hours of battery life. ↩