I just got my new 13" early 2011 base model yesterday and was using it with an external display while it was plugged in. After leaving it plugged in for a couple of hours after reaching 100%, I unplugged it and started using the notebook in mirrored mode with the display open (since you can't run clamshell mode off of battery power). When I went to bed last night, it had drained down to around 60%. I closed the lid and it went to sleep. I left the external monitor plugged in but I turned the power to the monitor off. When I came home from work today, upon opening the lid, I was shocked the battery had drained down to 20%! Why would it drain 40% while sleeping in less than 18 hours? Does it use extra battery power while sleeping when connected to an external monitor? I did have an external hard drive connected. Does time machine somehow operate while the MacBook is sleeping? I also have bluetooth enabled with a bluetooth mouse connected. coconutBattery is reporting 101% health. Any ideas?