From Apple's FAQ: 3. Disconnect the power adapter while the computer still on and start running the computer off battery power. You may use your computer during this time. When your battery gets low, the low battery warning dialog appears on the screen. 4. At this point, save your work. Continue to use your computer; when the battery gets very low, the computer will automatically go to sleep. 5. Turn off the computer or allow it to sleep for five hours or more. Why do I need to let it sleep for 5 hours if all I have to do is turn it off and back on again (as implied to me in step 5 with the word, "OR"). Won't you have to do that anyway once power is hooked back up? Or does the battery really "sleep" for 5 hours even when it's dead? How do you guy do this? About once a month before going to bed I load up a long-assed flash movie, unplug the magsafe and go to bed. The next morning I plug in the magsafe and power up.