MacBook turns off at 30-40% battery

Discussion in 'MacBook' started by PhazonUK, Jan 3, 2011.

  1. PhazonUK macrumors 6502

    Joined:
    Jun 1, 2010
    #1
    This has happened twice not. I'll be using my MacBook and it will have around 40-60 minutes worth of battery left, around 30% or 40%, and it will just shut off. No warning at all, it just turns off as if I've pulled the battery out.

    I plug it into the mains and turn it back on and it says I have at least 30% battery left.

    Is my battery dying?
     
  2. mallyman macrumors newbie

    Joined:
    Jan 3, 2011
    Location:
    United Kingdom
    #2
    Unfortunately I don't have an answer for you but I am also having the same issue. It occurs whether I have the power cable plugged in or not.

    Only started happening in the last 24hrs and no pop up comes on when running on battery to say it's low on power.
     
  3. ZebOfMac macrumors regular

    ZebOfMac

    Joined:
    Feb 13, 2010
    #3
    Have you tried calibrating the battery?

    What are you charge cycles and battery information?

    Cheers!
    Chris
     
  4. mallyman macrumors newbie

    Joined:
    Jan 3, 2011
    Location:
    United Kingdom
    #4
    Hi, not calibrated the battery as I'm not sure how it's done. The battery info is as follows:

    Health Information:
    Cycle count: 562
    Condition: Normal
    Battery Installed: Yes
    Amperage (mA): 3205
    Voltage (mV): 11881
     
  5. mallyman macrumors newbie

    Joined:
    Jan 3, 2011
    Location:
    United Kingdom
    #5
    I have looked at the instructions for calibrating the battery and this won't be possible. The battery disconnects at the 30-40% remaining level. To confirm I push the button on the battery and I am presented with 2 lights so not low enough to run through as the instructions advise because I don't get the 'low battery' alert anymore.
     
  6. Julay macrumors newbie

    Joined:
    May 28, 2007
    Location:
    Greater Philadelphia
    #6
    Same problem plus fluctuating health/max charge values

    I have the same problem. Battery dies without "reserve power" warning. When I start up again, iStat and Coconut battery both show 20% charge and 77% health. I have tried recalibrating twice. I have also noticed that the health of the battery fluctuates. Sometimes it is 77% sometimes 71% then back up to 75%, etc. Readings for maximum charge vary accordingly. Is the battery fried?
     
  7. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #7
    It's normal for the battery health to fluctuate. If you've properly calibrated and your Mac shuts off without warning when the battery isn't showing to be depleted, try resetting the SMC. This should answer most, if not all, of your battery questions:
     
  8. blackburn macrumors 6502a

    blackburn

    Joined:
    Feb 16, 2010
    Location:
    Where Judas lost it's boots.
    #8
    You can also try an when powering up the macbook, hold the alt key and let it drain the battery (don't let it boot mac os x or windows). It ignores power management and only cuts off when the battery is really empty.
     
  9. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #9
    Pressing the Alt key on startup displays bootable volumes: Mac OS X keyboard shortcuts
     
  10. blackburn macrumors 6502a

    blackburn

    Joined:
    Feb 16, 2010
    Location:
    Where Judas lost it's boots.
    #10
    Of course. The point is to not load the OS. So that only when the hardware cuts off the power it powers down. Just let it sit for a while, it heats the macbook a little while showing boot able partitions / volumes.
     

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