my battery life on the 920 wasn't acceptable in the beginning. after a couple of charges, the battery life has improved drastically. i am now able to do what i do on my phone and not have to worry about the battery life.
today however, something changed. i was playing wordament for a good hour or so. the battery went from 98%-70. took 2 calls, both lasting no more than 2 mins each. my location service is always off, bluetooth is off, wifi was off, and no other programs running in the background (this can be achieved by pushing the back button instead of the home button). my batter went from 70-40 just sitting on my desk not doing anything for about 3 hours.
i have the battery level for win8 on my phone and it comes with a nice graph to show your usage. the battery took a dive just sitting for 3 hrs. the graph looked similar to when i used nokia drive for the first time. nokia drive eats up a lot of power on this phone.
i'm starting to suspect the phone is not turning off specific apps even after you exit out the program. this should be an easy fix for nokia/microsoft. i hope...