What can cause "Android OS" process to use high percentage of battery?

I've read a bunch of forum posts about the Android OS battery drain bug. This is where the 'Android OS' process is showing large percentages in the battery statistics.

For me, I'm running 2.3 Gingerbread. I don't use bluetooth or GPS. I'm on 2G most of the time. Some days I get 40 hours out of a battery. On these days in the battery usage settings, the 'Android OS' process uses about 3% of battery. However other days I get about 8 hours with similar use. On these days the 'Android OS' process uses about 35% of the battery. I really want to find out what causes this.

The fixes suggested so far are:

1. Reboot (Temporary).


2. Turn off and remove battery for a couple of minutes.


3. Reset battery stats.


4. Change WIFI sleep policy.



5. Use a task manager


6. Flash stuff to the phone.


7. Revert to older versions of the OS (not really a fix).

Does anyone know the definitive cause of this problem and the correct fix? Or is it possible there are multiple issues that cause this so different things will work for different people?

Here are some of the threads: