It's the 4G that's at fault. Yesterday I started the day at 8 am, no phone calls, did use Bing for 2 20 minute trips...btw Bing sucks big time on Android...can never keep it's GPS location, has no voice guidance. Anyhow, by 1 pm the battery was down to near zero. So later I switched to 3G. Then I had to download some apps so I went back to 4G, and in minutes I saw a bit of a battery drop. I plan to run on 3G today and see what happens.
Incidentally there's a browser BUG. When a browser window is open, and you go to settings, and tap on windows, you see a list of open windows. Each one has a red button with a - sign on it. You have to tap on that red button to remove that window...but on my phone you try to tap on it and you just bring up that window again, it does not sense your touch on the red button. Wonder if others have this problem.
Lots of good things about this phone compared to my Samsung Omnia 2 which is obsolete and had a miserable browser, Opera Mobile. But I'm really not sure whether to keep this phone!