I have had the same issue off and on since the last update (security fix for internet access). "Android OS" shows as the top user of the battery on the bar chart when it is normally less than 5%. I have not been able to figure out if it is some specific app or something else. Usually I can get it back to more "normal", with Display using most of the battery, by doing a "restart" of my phone. A battery pull has also done the trick. The problem is the issue keeps coming back every few days.
I have Watchdog Lite installed as suggested by another post, but have not come up with anything obvious from that yet although one time when I had the issue it reported "HTC IQAgent" as using > 30% of the CPU for an extended period.