Remaining battery reading not accurate.

Discussion in 'MacBook Pro' started by doxavita, Jul 14, 2010.

  1. doxavita macrumors 6502a

    Joined:
    Jul 6, 2010
    #1
    The remaining battery indicator (top right) is not completely accurate. The measurement (time) constantly varies.

    As far as I know a 13" MacBook Pro should have 10 hours battery time. In this case the reading constantly changes from about 8:52 hours then back to 9:12 hours, 9:34, and other readings, etc.

    Is this normal?
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Calibrate it. Also, the time remaining changes dynamically as your current battery load changes. Some things draw power faster than others.

    This should answer most, if not all, of your battery questions: Apple Notebook Battery FAQ
     
  3. doxavita thread starter macrumors 6502a

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    Jul 6, 2010
    #3
    Well, yesterday my battery got pretty low (18%), and I fully recharged it.
    Don't know if that counts as "calibrating".
    If not, I'll follow the exact steps for that.
     
  4. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #4
    That's not calibrating. You'll find a link to the proper instructions by following the link I posted.
     
  5. doxavita thread starter macrumors 6502a

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    Jul 6, 2010
    #5
    OK, I'll do that. Since calibrating takes many hours, I can do the entire procedure in more than one day, right?
     
  6. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #6
    Do it without interrupting the process.... overnight is best
     
  7. xbeamelite macrumors newbie

    Joined:
    Jul 2, 2010
    #7
    yeah, just use it untill you ave no power. close programs and let it go to sleep by itself. Then wait 5 hours (overnight). and then I left it in charge before work. Came back and started using it again. voila
     
  8. NKT macrumors regular

    Joined:
    Jun 18, 2010
    #8
    I calibrated my MBP when I first got it and followed the instructions GGJstudios. It worked great.

    The only thing I did additional was to use the info from this site/video to help drain the battery faster:

    http://www.unixweblog.com/2010/05/calibrating-the-battery-on-an-apple-macbook-macbook-pro/

    By setting up 4 terminal windows I was able to go from a full battery to completely dead in just over an hour. Just make once the computer shuts off that you leave it for ATLEAST 5 hours. This will finish the discharge of your battery. At that point, just plug it in and leave it.
     
  9. doxavita thread starter macrumors 6502a

    Joined:
    Jul 6, 2010
    #9
    "5. After your computer goes to sleep, turn it off or allow it to sleep for five hours or longer."


    1. Does that mean that when it's in sleep, I have to wake it and then shut it down?

    2. If I shut it down, how many hours do I have to wait?
     
  10. NKT macrumors regular

    Joined:
    Jun 18, 2010
    #10
    Once the battery gets really low you'll get a notification. Keep using the laptop until it shuts off on it's own. At this point, just set it aside for 5 hours. Do not try to power it up again.

    After 5 hours, just plug it in and wait a few minutes. Then power up and let it charge to full.
     
  11. doxavita thread starter macrumors 6502a

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    Jul 6, 2010
    #11
    So when it goes to sleep, I can just close the display and leave it like that for at least 5 hours?
     
  12. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #12
    No, when the battery gets low enough, it will automatically sleep or power off. Just let it sit like that for 5 hours before you reconnect the charger.
     
  13. NKT macrumors regular

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    Jun 18, 2010
    #13
    Yes.
     
  14. doxavita thread starter macrumors 6502a

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    Jul 6, 2010
    #14
    Yesterday I fully recharged my battery (until green led in power adapter) and I'm pretty sure 2 hours passed after that.

    Following that link you provided me (Apple Notebook Battery FAQ) there's this comment:
    "AppleCare support recommends that if you leave your Mac plugged in most of the time, unplug it every 2 or 3 days and run on battery down to somewhere around 50%, then plug it back in. That keeps the electrons moving."

    So today instead of waiting until 50% and recharging, I can just wait till 0% and starting doing the battery calibration right away, right?
     
  15. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #15
    The calibration steps are very clear. Read the steps and follow them exactly. You can calibrate at any time, but remember that calibration starts by fully charging your battery and leaving it fully charged and plugged in for at least 2 hours.
     
  16. NKT macrumors regular

    Joined:
    Jun 18, 2010
    #16
    ^
    This
     
  17. doxavita thread starter macrumors 6502a

    Joined:
    Jul 6, 2010
    #17
    Yes, that's what I did yesterday (recharging and waiting 2 hours). So today I'll just do the calibration.
     

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