[Update: Firefox Sync does not drain my battery any more, but I've had similar experiences with Exchange Sync and Soundcloud. My latest discovery is Juice Defender, my battery now lasts between 36 and 48 hours!]
From May 29th until yesterday I was experiencing unacceptable high battery drain on my Samsung Galaxy S II with Ice Cream Samsung. Instead of the normal 24-36 hours, my phone only lasted for 5-7 hours. According to the battery stats, “Android OS” was responsible for up to 80% of total power consumption, where one normally would expect the “Screen” to be the biggest consumer. CPUSpy showed that my phone only rarely entered “Deep Sleep”. The problem only disappeared when I disabled “Data” entirely, not when just disabling “Synchronization”.
Based on information in this issue on the Android-bugtracker, I wasn’t the only one to experience this problem. There seemed to be multiple solutions which worked for some but not for others. Apparently “Android OS” was just the poor sucker to get the blame, while in fact other applications can keep your phone awake.
If you ever experience a similar problem, here’s how I finally stopped the battery drain: I uninstalled a number of applications and checked battery usage. If the discharging continued at the same rate, I re-installed the application and went for the next bunch. And just before uninstalling my beloved Firefox Mobile, I deactivated Firefox Sync, which I (only then) noticed was trying to sync continuously. Ouch! I removed Firefox Sync from the Synchronization services and battery life is back to normal since. One of these days I’ll re-enable Firefox Sync to see if the problem returns. If it does, I guess I’ll have to dive into ADB for debugging info and report back to Bugzilla? Good times!