There are lots of reasons why battery life in smartphones might fall well short of expectations. You could have too many services turned on all the time, each one sipping juice from the lithium-ion battery. There could be a rogue app that's flawed or poorly coded and constantly doing things in the background. It could be a software snafu, and it could be a hardware problem. Or, as one Apple Genius put it, the phone could be stressed out, man.