Freezing System Update Service Drains Battery?

I'm rooted on 5.0.1 (24B) and, of course, trying to prevent an update to 35B. Using the DisableService app, I've disabled all the System Update services. (Disabling the "SystemUpdateService" under Google Play Services or Google Services Framework does not prevent the system update notification.) When I do this, my battery life is TERRIBLE. Battery gets warm and lose 10% an hour or more when idle (screen off).

Any thoughts on why this might be happening? Any other techniques to kill the system update process in 5.0.1?

TIA