Calibrate your battery

If you've noticed your MacBook or MacBook Pro battery has not been reaching up to it's full potential, you probably have never calibrated it before. This is something not many people know about, and can really help you out. What calibrating does is keep your battery functioning at it's fullest capicity and keeps it healthy, for a longer battery lifespan. Apple recommends you calibrate your battery every 2 months. There are only a few steps to doing this, and before you do keep in mind this takes hours to do.

1.Plug in the MagSafe power adapter and fully charge the MacBook or MacBook Pro battery until the light on the MagSafe connector changes to green and the Battery icon in the menu bar indicates that the battery is fully charged.

2. Allow the battery to rest in the fully charged state for two hours or longer. You may use your computer during this time as long as the power adapter is plugged in.

3. Disconnect the power adapter with the computer on and start using it with battery power. When the battery’s charge gets low, you’ll see the low battery warning dialog on the screen.

4. Continue to keep your computer turned on until it goes to sleep. Save your work and close all applications when the battery’s charge gets low and before the computer goes to sleep.

5. Turn off the computer or allow it to sleep for five hours or longer.

6. Reconnect the power adapter and leave it connected until the battery is fully charged. You may use your computer during this time.

And that's it! like I said, of course this is going to take hours so plan when you're going to do it. 

Here's the link to Apple site- http://docs.info.apple.com/article.html?path=Mac/10.5/en/9036.html

For iBooks and PowerBooks-http://support.apple.com/kb/HT1490