I installed the SMC change before I saw Rich's warning above, so I tried an experiment. With WiFi on and brightness at 1/3 max (and display sleep set to never), I played an mp4 video fullscreen in a loop. Battery life was just over 4 hours. I'm not sure how that compares to normal. Walt Mossberg got over 6 hours in his review of this machine at 100% brightness, but that was with just a loop of music playing.
9/7/12 at 12:12am