Can you overcharge the Macbook Air?

No, provided your system is working properly, the battery can't be overcharged.

The charging system on the MacBook Air is carefully monitored and controlled by the System Management Controller, and will shutoff power to the battery when charging is complete. Moreover, it also controls when charging will recommence, so as to help prevent cycling of the battery when it already close to full charge.

Don't worry. Leave it plugged in, if you choose. Just let it cycle from time to time (once a month or so), so that the battery itself will perform at peak efficiency.

Is there anything on Apple.com where you found this information?

Check this Web site and the links from it for everything you'd ever want to know about batteries. The short form is this: The battery cannot be over charged. Plug it in and keep it plugged in so that when you go off on the road it has a full charge. When you have depleted about 80% of the charge you'll get a warning that you are on reserve power and it is time to start looking for a power plug. Do not drain the battery 100%. While you cannot overcharge the battery it isn't good to keep it plugged in all the time. At the very least unplug it and use the battery at least once or twice a month.

Following the above advice which came from Apple my 2009 MBP battery still keeps better than 80% of its charge and has 112 cycles used. Given its age I expect the battery will probably need to be replaced before long but I'm amazed that it is doing this well after nearly 5 years of use.

awee wrote:

Is there anything on Apple.com where you found this information?

http://www.apple.com/batteries/