Originally Posted by marvfox
I thought the correct procedure was once a month.If the battery is not charged that is not good for it right?
Well, this is the official response from Apple:
Originally Posted by Apple
For proper maintenance of a lithium-based battery, its important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her notebook on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month. Need a reminder? Add an event to your desktops iCal. When your battery no longer holds sufficient charge to meet your needs, you may choose to replace it. If your notebook came with a built-in battery, you should have the battery replaced only by an Apple Authorized Service Provider.
So, if you rarely unplug your MBP, once a month is necessary. If you have your MBP plugged in 50% of the time (like I do), it's not as important. A few times a year should be fine.
Hope that helps!