It will, eventually. The internal battery is enough for several minutes to several hours of sleep (depending on the model), or probably several days while shut down. It is rechargeable; the recommended procedure to charge it is to charge the main battery, then leave the computer plugged in for 24 hours. However, is there any particular reason to NOT leave it plugged in? It might help prolong the life of the internal battery - they don't die often, but it can happen... And it's not as easy to get replaced as the internal batteries used on a desktop Mac; the batteries are custom, and sometimes come permanently attached to the circuit board for the PMU. "T.L. Miller" <tlmiller at mac.com> writes: > Apple recommends that you remove the recalled battery and plug in > the AC > adapter when you want to use your Mac. If the computer is turned off, > will the internal battery get drained if the adapter isn't used after > the battery has been removed?