Over the last month with my L920 and my wifes L820, I have found many apps that drain the battery and many that you would think that they would, but do not. I am convinced that either they are not developed correctly, or there is a bug in the OS which these certain apps are "exploiting" (for lack of a better word). As a general rule I have found that if the app has not been updated for WP8 specifically, then it has the potential to be a big battery drain. I am still slowly experimenting, but I believe that somehow, certain apps when installed somehow affect other apps and battery life. For example, Skype seems to be the culprit of the MS account getting stuck in sync. For me, Nokia Drive would drain the battery even if background task was blocked, I had to uninstall it and now go 14-16 hours and still have 50% battery. I have had others report that they have no issue with Nokia Drive once the background task is blocked. Either way, we shouldn't be having to sit here and figure out how to make the battery last. MS needs to fix it ASAP because most people don't want to fiddle with it. On the bright side though, even when my battery was draining fast, it was still on par with my brother's GS3 or my buddy's iPhone 5. Right now it totally crushes them.