I use the tablet and extended battery a lot for school. I always have wireless on, bluetooth off, display brightness set at 25% for taking notes and 100% when doing problems. I have set one of the hot keys to turn off the display. Therefore I turn the display off quite often to conserve battery. I am not sure how long the battery lasts exactly but I would say 7 hours or so. Here is how my day has gone so far.
__These are all estimates__
1 hour and 15 minutes of note taking
3 hours of doing problems(reading a lot of the time so I turn off the display)
1 hour of reviewing notes
and looking at my tablet right now, I have 2 hours left.
So that totals about 7 hours and 15 minutes.
Works great for me :D