I was also getting severe Android OS battery drain for the last few days. I lost 60% battery life in just 3 hours!
I fixed it by "recalibrating" (or at least I saw it called this elsewhere on the internet) my battery. I simply used my phone until the battery died and my phone automatically shut off. Then I kept trying to power on the phone until it stopped attempting to turn on (this just makes sure your battery is truly dead; i doubt this does anything useful though). Then with the phone off, I charged until 100%, then continued charging another 2 hours (to make sure battery is really full). Then I turned on the phone. After this, I am getting excellent battery life and Android OS is using far less battery.
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EDIT: No longer true. The issue eventually came back and has been plaguing me since.