One Google project manager blamed the Skype app, saying that an update to the Android version of the app caused it to screw up the mm-qcamera-daemon process, allowing it to get stuck, consuming the CPU cycles that ate away at the battery life of the stock Android phone. While there have been a few bug fixes for the handset, the problem still exists for some. Android 4.4.3 included changes to the camera that did take away the problem for many. For some though, the rapid draining of the battery continues.
The good news is that the issue is now listed in the AOSP Tracker as a "future release," which means that when Android L is ready for public consumption, the problem will finally.disappear. Hopefully, it won't be too late for some Nexus 5 users to finally enjoy using the handset.
source: AOSP via AndroidPolice, AndroidAuthority