99% shouldn't be "full charge"

Discussion in 'MacBook Pro' started by horiveira, Apr 28, 2010.

  1. horiveira macrumors newbie

    Mar 4, 2010
    A few days of battery calibration and poor battery performance, my "full charge" doesn't go past 99%. I know that's extremely close to 100%, but I don't think that should happen in less than one week of use out of a brand new MBP.

    I do realize that the poor battery performance is normal just because I do perform some heavy stuff (or at least heavy enough to drain the battery) but my main concern is the 99%="full charge."

    What's going on? Any similar situations?
  2. jav6454 macrumors P6


    Nov 14, 2007
    1 Geostationary Tower Plaza
    Think of it as filling a water glass. At first it goes fast because the glass is empty. But as it gets fuller the filling slows down as to not overfill the glass. It is not a perfect science and you will end up with 99%, don't worry it's normal.
  3. tekchic macrumors 65816


    Apr 19, 2010
    Phoenix, AZ
    I calibrated mine the 2nd day I got it and I still top off at 98%. It was reading 98% before calibrating too, so I don't know what the calibration actually did for me. :confused:
  4. thinkbig12 macrumors member

    Jul 23, 2008

    srry had to say it :D cmon.. 1% less or 1% more, who cares.
  5. IceBreakerG macrumors member

    Apr 27, 2010
    Cordova, TN
    I've noticed mine will stop anywhere from 97% to 100% depending on how full it was before I started charging initially. If the charge is around 90%, it won't charge to 100%, but if it goes past say, 70% charge, then it will charge to 100%. This is normal because the macbook pro uses smart charging on the battery. It's supposed to work that way.
  6. snaky69 macrumors 603

    Mar 14, 2008
    The controller on the battery will also let it drain down slowly to 95% and trickle charge it back up to 100%, it keeps the battery healthier on machines that are plugged in all the time.
  7. Tom71 macrumors regular


    Apr 27, 2010
    It has been said before, I say it again as well.

    It's not good to always charge batteries. It will degrade battery power. It's why so many batteries in notebooks are broken when people said they barely used them. Most likely they were killed by repeated daily charging of a few percent of capacity.

    I'm actually happy to see this behavior of not charging to 100%. I've seen it stop at 95% at times and it's just an indication that the OS is smart enough to not always charge the battery for no reason.

    I wish someone could update the post in the battery "wiki" on macrumors that says that a charge of 98% is a good indicator for a battery needing "recalibration". It's entirely untrue.

  8. diablo2112 macrumors 6502

    Apr 16, 2010
    Good grief, the nitpicks here on this site are just laughable. Are you kidding?

    The chemistry in modern batteries - especially the A123 Li-polymer cells used in laptops - is exceptionally complex and difficult to implement. Allow a cell to fall below a specific voltage (roughly 3.0 volts), and the battery will literally disintegrate. Hydrogen will boil off, and fire can (and has) occurred. Charge too-much, and you unbalance the cells, degrading performance. The need to keep each cell to the same voltage within about 0.01 volts is critical to obtain maximum performance from Li-Polymer batteries. All of this is complex and demands a very sophisticated battery controller, which monitors each individual cell. The liability to the manufacturer is large, and they take (a completely understandable) conservative approach to things like capacity and charge rates.

    Just a decade ago, you'd have to be satisfied with Nickel-metal-hydride (NiMH) cells which weighed twice as much and had less than a third the capacity of todays polymer cells. And 20 years ago, you'd be stuck with Nickel Cadmium (NiCd) cells which were half again as heavy and about 60% lower in capacity than NiMH.

    The idea that we have a laptop that can now last all day on a single charge while providing the computation power of a supercomputer from the early 80s and graphics abilities that were unheard of 10 years ago is astounding. This is Star Trek technology in our lifetime.

    All of the clueless nerds here who complain I'm not getting the last 1% of whatever out of my machine need to spend a little more time actually learning what they have.
  9. bob5820 macrumors 6502a


    Jun 23, 2006
    35°0′36″N 80°40′45″W (35.0
    Mine's reading 101%. See nothing to worry about, it all balances out.

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