Look at the battery graph on the second page (tap the graph on the first page to get to th second page).
Is is slowly running down from 100% in 2 hours, or does it stay almost fully charged, then suddenly drop to 0?
If the second one, see my post at
http://forums.androidcentral.com/as...-mini-shutting-off-80-charge.html#post4501080
If it's dropping evenly but just fast, it could be a battery at the end of its life (do you normally discharge it to less than 40%? - regularly discharging a lithium battery to 0 can kill it in a few months) or it could be something shorted on the motherboard, draining the battery quickly, a rogue app that's drawing lots of power, or a looped SD card, causing the media scanner to run constantly. (And those are just off the top of my head - there are plenty of other possibilities.)