Recently I have been suffering from various battery issues ranging from fast battery drains to unexpected shutdowns at safe battery levels. But most striking is the fact that I lost all system data (like system app data, WiFi Access points, etc) after my most recent shutdown! The strangest thing is that i have not lost any data of any non-system apps!

I guess my question would be: Can a shutdown due to critical battery cause my to lose only system data? If yes, how did it happen and how can i prevent it?

The Shutdown: The shutdown involves a short flickering of the screen (in a rare case it also made a soft high pitch sound with a very soft pop) followed by the screen going completely black! All happening within a fraction of a second right in the middle of an app without any warning or prompt making it less like a typical shutdown and more like a crash!

Also worth mentioning:

  • After the phone freezes sometimes, I force a restart and after powering up the battery would have dropped up to 30% (that makes a 30% battery drop in under 2 minutes!)
  • The frequency of these shutdowns increased after using a battery hogging app (EveryCircuit)
  • I have 2 Samsung Galaxy SII batteries which I occasionally exchange
  • I once kept my phone for charging at 3% but instead it discharged to 0% before the charge began to climb
  • (Edit) I have not overclocked or over-volted any hardware manually, but I have for a short amount of time under-volted the 200MHZ power state as an attempt to save battery (but I cant say whether the ROM itself has done any Over/Under-Clocking/Volting)

Things are starting to get hilarious with my phone! Any insight is appreciated!


  • I have a rooted Samsung Galaxy SII (18 months old)
  • Running Kitkat ROM (CyanogenMod 11)

Similar symptoms addressed here

  • The two obvious things are the battery needs replacing. Have you overvolted anything, that could do it. Also CyanogenMod 11 on Samsung phones is not a great combination. They are rought, nightly builds and they are not suitable as a daily driver. I seem to be spending a lot of time telling people to ditch it for now until it is stable. It's a great ROM but it is buggy, laggy, missing features and error prone on Samsung devices still. The lack of Samsung KK kernels just makes it worse. New ROM, new battery I think.
    – RossC
    Jan 29, 2014 at 10:09
  • Great advice! And no i haven't overvolted or overclocked anything personally (as for the ROM itself over-volting hardware, I can't say... I edited the question for more information). Please recommend an alternative ROM for samsung devices. (Clarification: Do you mean that it is best i get a jellybean ROM rather than KitKat Rom for now?)
    – reubenjohn
    Jan 29, 2014 at 10:18
  • Well, it depends really on what you want. KitKat is still releatively new and there are know issues (kernel issues, random reboots and certain functionality not working.) From my experience there are good KK roms, but the 4.3 are more stable as they've had more time to work on them, and full kernel source code. I'm afraid I don't have an S2 so I don't know what ROMs are good, but check out XDA and try a couple of them and see what suits. CyanogenMod and Samsung don't seem to work that well together until the 'stable' builds come out months and months later.
    – RossC
    Jan 29, 2014 at 10:43


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