The first week wasn't very kind to me, I got the feeling in my stomach that something wasn't right... The battery would drain VERY quickly. But now two weeks later, I'm finding myself through a whole work day with moderate use with 60% remaining. It's got to calibrate.
+1
*Practiced the full charge > unplug > reboot > charge to full again suggestion over the last couple days.
We really need to get off this myth of "calibration" for Li-ion batteries. All calibration does now is just give you a more accurate reading, its not a way to squeeze more juice out of your battery. Battery memory doesn't apply to Li-ion batteries, only nickle based. You only want to do calibration every few months or when you notice your readings kinda go bonkers (li-ion shouldn't be completely discharged often.) This will do nothing more than give you an accurate reading, you're not going to suddenly get 6 more hours out of it.
OP: Many things can cause battery drain, a bright screen probably being the biggest. LTE also drains quicker than 3G, things have got much better though in that department.
My first day the battery drained 26% while I slept, it got better the next couple of days. It may be that the in the box charge was "off" in some way?
I?ve had my 8X since November 16[SUP]th[/SUP]. The only thing I recall doing immediately was turning off NFC. With my screen at medium brightness, I can easily make it through a full day and more with moderate use. Now if I am watching a ton of video or playing games like Civilization Revolution for hours, my battery drains very fast. I feel the battery life of my 8X is easily on par with iPhone 5 and very close to the 4S I use for work.
That said, some have experienced 8X battery problems. If you feel you have a defective unit you should exchange for one that works properly.