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I'm trying to figure out what's using my battery life by looking at the battery page in Settings. (I don't know if this screen is Cyanogen specific, or a stock Android feature.) Here's a recent screenshot of that page:
Current battery level: 67%
Use since last full charge:
- Android System: 3%
- Screen: 2%
- Cell Standby: 2%
- Ironclad Tactics: 2%
- Google App: 1%
- Android OS: 1%
- Google Play Services: 1%
(It may not be clear from the screenshot, but that's the end of the list: there's nothing off-screen.) I don't know whether those percentages are supposed to add up to 100% (logical) or to 33% (the amount of battery used so far), but either way, they actually add up to 12%. No amount of rounding error can explain that. At best, 2/3 of my battery usage is totally unaccounted for.
This is a common occurrence. I have another screenshot where my battery level is 18%, but the sum of all the used apps is only 44%.
What could be using up so much battery that wouldn't show on this list? Or alternately, could some battery usage pattern could cause this screen to grossly underestimate usage of a particular app? Or could a faulty battery, that drains more quickly than it should for a given load, cause this?