When you use your Macbook a lot like I do, you should do something called calibrating. Calibrating basically syncs your battery with the accurate percentage shown in your menu bar. In your menu bar you will see your battery icon and it will tell you how much battery is left. After using your Macbook for a while, the percentage shown in the menu starts to slowly get less and less accurate readings of where your battery life actually is. So it is important that you calibrate your battery so that you know most of the time what your actual battery life is.
This process is not to help save you battery life, it is just for a more accurate reading of your battery life. Also, this process can be done for all current and past Macbooks and Macbook Pro’s. Here are the steps you want to take to calibrate your battery.
Plug in your Macbook to the power adapter and let your Macbook fully charge until you see the adapter light turn green and the battery icon in the menu bar say “Charged”
Let the battery rest in the “Charged” state for at least two hours. You can use your computer during this time, just make sure it stays charged. When this is done, unplug the power adapter, and use the computer as you normally would. Then you will want to use your computer until you get to the “Low Battery” signal. When it gets to this point, you are going to want to make sure to save all your work.
Then, let the computer continue to drain its battery until it goes into “Sleep Mode.” When the computer goes into Sleep Mode, let it stay in this state for about 5 hours. I usually try to time this for about the time I go to bed at night so that way I will let my Macbook just sleep for the night.
The last step is to then reconnect the power adapter and fully charge the battery. Once this is done, you are now finished calibrating your battery. So why do this? Well, the main reason is you want to make sure that you are getting the most accurate reading of your battery. No matter what, your battery life will slowly get shorter and shorter. But as time goes on, you can make sure you get an accurate reading of what kind of battery life you are really getting by getting it calibrated every once in a while.
My suggestion is that you are a heavy computer user, meaning you use your Macbook for at least 5-8 hrs a day, you are going to want to calibrate your battery at least once a month. If you use your Macbook less than that, then maybe every few months would be fine. Hope this helps some of you get a better reading on your battery. I know this has saved me a few times from thinking I needed a new battery for my Macbook, only to discover that I needed to calibrate my battery.
As many of you know, Apple announced new and 
