I used to get my battery to last from 8am to about 10pm at night with it in the red zone. Recently though I have been working more from home and now have an airave and connect to the wifi network. Now all of a sudden when I go to bed I'm over half maybe even 3/4 of the battery is left. My thinking is some of the battery drain may be caused by poor reception. For those of you with battery issues or issues on some days and not others, look at how much reception your getting in addition to use and radios and all that. Maybe the problem is sprints network.