Some times smart phone batteries are depleted because of “energy bugs” in the software that cause the phone to use excess energy.
Researchers have proposed a method to automatically detect a new class of software glitches in smartphones called “no-sleep energy bugs,” which can entirely drain batteries while the phones are not in use.
via 'No-sleep energy bugs' drain smartphone batteries.
Have you ever installed an app and then noticed your battery life was worse than before so you uninstalled the app? End users are starting to discover these “e-bugs” although they are unlikely to be aware of the power issues lurking under the covers - but they do notice when battery life worsens.
Most app developers do not do energy analysis of their applications to learn how the app impacts battery life. My own research presently involves issues with application software and battery life.
Solving the short battery life problem of smart phones will require improvements to all aspects of smart phone technology, from the network, to the phone technology and battery technologies, to the operating system and applications that run on the phones. Solving the battery life problem is complex but, obviously, one that most people want to see solved!