computer battery drains to 99% when plugged in!?

Discussion in 'MacBook Air' started by askrib, Aug 23, 2011.

  1. askrib macrumors member

    Apr 15, 2011
    Hey guys anyone having this problem or know why this would happen?

    I come back to my macbook air i7 256ssd that is plug in that was 100% is now at 99% and i never un plugged it! Whats the deal with this??
  2. Mlrollin91 macrumors G5


    Nov 20, 2008
    Ventura County
    Mine does it too, really annoying. My 2009MBP did it as well, but it would then drop to 98% and so on until it reached 94% and recharge itself back to 100%. This process took about a week and a half being plugged in 24/7. My MBA drops to 99% within an hour of reaching 100% and stays there..Doesn't go any lower.
  3. GadgetGeek407 macrumors 6502a

    Mar 26, 2009
    I got my i7 13 tonight haven't charged the battery yet came 88% out the box now have like 26% should i plug it in or don't plug it until totally dead?


    btw out of box my cycle count was 0 and now it says 1 and i never plugged it in SMH
  4. benhollberg macrumors 68020


    Mar 8, 2010
    My MacBook Pro does this all the time. I have it plugged in 99% of the time and it is always running, sometimes it'll go down to like 93% even. I don't think it is that big of deal, well maybe for me because I use it as a desktop pretty much.

    Note though, I have pretty much killed the battery doing this, I can only get about two or 2.5 hours out of it. Sometimes I just let the battery drain while use then plug in to cycle it.
  5. askrib thread starter macrumors member

    Apr 15, 2011
    Thanks. Its good to know I'm not the only one with this.
    But I'm wondering why this happens or if its an OSX bug?
  6. ZBoater, Aug 24, 2011
    Last edited: Aug 24, 2011

    ZBoater macrumors G3


    Jul 2, 2007
    Sunny Florida
    No, this is by design. Keeping the battery at 100% all the time kills it. The system kinda lets it drain a little bit before charging it again to prevent overcharging.
  7. askrib thread starter macrumors member

    Apr 15, 2011
    Oh really? Interesting......Thanks for the data! That makes some sense.

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