After charging my Galaxy SII (ICS) overnight, I unplugged and started using the web browser. Battery indicated 100%. After 20 minutes the screen went black and the phone rebooted, then it popped up a battery low warning. On plugging back in, it seemed to charge normally for a while and then jumped from 80 to 100% almost instantly.

I would post a screenshot of the battery screen but don't have enough reputation - it shows charge starting at 100%, dropping slowly for 20 mins, then instantly down to <10%. From there I plug in and it goes slowly up to 80%, then instantly up to 100% again.

Anyone fancy having a guess at what is going on here?

  • Are you rooted?
    – Liam W
    Dec 8, 2012 at 11:19
  • Until you can post screenshots, you can upload them to some image hoster and include a link here. Somebody with enough rep then can decide to convert that.
    – Izzy
    Dec 8, 2012 at 18:42

1 Answer 1


My guess would be that the battery calibration data got lost. Probably through the crash.

  • Should that really matter? I always thought that file (batterystats.bin AFAIR) only holds data about which app cunsumed how much. Isn't the current charge of the battery decided via its voltage?
    – Izzy
    Dec 8, 2012 at 18:43
  • The voltage and charging current depends from battery to batterylevel. Therefore Android needs some calibration information to display the battery percentage.
    – Flow
    Dec 8, 2012 at 23:53

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