Calibrating your portable's battery

If you want to able to use your laptop whenever, it is the bes to keep your battery as good a state as possible. This is especially true for Intel portable CPUs that can have fanciful specs for battery life and sometimes have problems.
A technical note issued by Apple in this regard give the calibration procedure ( http://docs.info.apple.com/article.html?path=Mac/10.5/en/9036.html ). Here is the content:

To calibrate the battery:
1 - Connect the MagSafe power connector and recharge the MacBook or MacBook Pro battery until the light of the adapter turns green and the battery icon displayed in the menu bar indicates Loaded.
2 - Let the battery remain fully charged for at least two hours. You can use your computer during that time but you need to leave the power adapter connected.
3 - Disconnect the power adapter while leaving the computer switched on to use the battery as a power source. When the battery is nearly empty, a dialog will warn you.
4 - Continue to use your computer until it goes into sleep mode. Save your work and close all applications just before the battery drains to the point of suspension of the activity.
5 - Turn off the computer or leave it idle for at least five hours.
6 - Plug in the power adapter and leave it connected until the battery is fully charged. You can continue to use your computer during that time.
Repeat the process of calibration about every two months in order to optimise the performance of the battery. If you use your MacBook or MacBook Pro erratically, it is preferable to recalibrate the battery at least once a month.

You can see the carrying capacity of your battery with many programs, or simply in the power component information system.
Sometimes, after a comprehensive calibration, you will see battery capacity significantly diminished. That is not the process that has caused this, but regular use. Calibration only tests the battery on a full cycle in order to avoid giving you erroneous battery-time-left information.