Android Framework Engineer, Dianne Hackborn have a post in Google+, stated that This file is used to maintain, across reboots, low-level data about the kinds of operations the device and your apps are doing between battery changes. That is, it is solely used to compute the blame for battery usage shown in the "Battery Use" UI in settings...It has no impact on your battery life.
Read the full post: https://plus.google.com/105051985738280261832/posts/FV3LVtdVxPT
