Why don't the percentages on the battery chart add up to anywhere near 100%? 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:



Transcript:


  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?
Since you have last charged your device, its displaying the ratio [usage time/time since charged] * 100 of that service
It might be that you didnt use any service and the screen was off most of the time
If you use many apps simultaneously (consider using 4 apps at a time) using these all the time till your phone gets discharged will show the time for these apps to be 100% but if you add these %ages for all the apps it will be greater than 100