Engadget got 11 hours on looping video, 50% brightness, LTE. 16-21 cant remember with LTE off.
There used to be a power management widget; look for that or a 4g toggle widget, etc. Disabling data if you dont need it and minimizing brightness will max battery.
Power management widget is no longer in market; Go power master looks good.
I just downloaded it; dont see a LTE toggle. Downloaded fattin data toggle--it turns on/off mobile data, but has no cdma/lte mode. 4g toggle is a widget which is a shortcut to mode.