Battery got better?

Discussion in 'MacBook Pro' started by barnum1, Nov 13, 2014.

  1. barnum1 macrumors newbie

    Nov 29, 2009

    something strange happened recently: I have an MBP late 2008, and I purchased a new battery for it in July 2013. Pretty suddenly this autumn, the Battery health went down to 25% and the Apple shop said: too bad, not much we can do.

    But, after a week or so, Battery health has gone up to 91%! And I can run the Mac longer on the battery, so it doesn't look like false numbers.

    Anyone knows how this could happen? Could it be that the health monitor got wrong data when it sadi 25%? I have done a couple of "cycles" since, but can that help this much? Or is the battery so unstable that anything can happen now (keeping my fingers crossed....)?

    (I have used both Coconut battery and Battery health, and they both shoiw the same.)

    Thanks for any insight!
  2. Samuelsan2001 macrumors 604

    Oct 24, 2013
    sounds like a problem with some cells

    Who knows mate could be some cells failing or could be a loose connector. To be honest it sounds like anything can happen. Enjoy it while its working well.
  3. GGJstudios macrumors Westmere


    May 16, 2008
    I would have asked for another opinion. Get the manager involved. Although your MBP is no longer under warranty or AppleCare, if a battery drops that much in a few months, I would take it back to Apple, as the battery should retain 80% capacity up to 300 cycles. The fact that it would drop to 25% (if that number was accurate) could be a sign of a potentially defective battery.

    It is perfectly normal if your battery health (maximum capacity) is more or less than 100%, even when brand new, or if it fluctuates up or down over time. What is definitely not normal is that much fluctuation. I would keep an eye on it for a while and if you don't see any more wild fluctuations, it could have been a false reading. You might also try calibrating the battery. See the instructions in the CALIBRATION section of the FAQ, linked below.

    The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
  4. barnum1 thread starter macrumors newbie

    Nov 29, 2009
    Thanks for the replies. I have read the FAQ, and I have done Calibrations, but it did not seem like that helped in this case.

    About the warranty for batteries, Apple claims that they are "consumables" so only one year. I think that one should expect a $150 commodity to hold longer, but that's another story...
  5. GGJstudios macrumors Westmere


    May 16, 2008
    If you buy AppleCare on a new Mac, batteries are covered for defects for 3 years, not just one.

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