Battery cycling - when does it shut down vs sleep?

Discussion in 'Mac Basics and Help' started by cricketbird, Nov 16, 2008.

  1. cricketbird macrumors member

    Joined:
    Feb 17, 2008
    #1
    I've been advised to occasionally drain my MBP's battery completely (until the computer automatically goes black) and then charge it completely to "cycle the battery" or maintain it.

    Sometimes, when I do this, it shuts down the computer, and I have to restart it. Sometimes it just puts it to sleep. I'd prefer, of course, to be able to pick up where I left off. Is there a rationale behind the computer behavior when it runs out of juice? Is there something I can do to get it to just sleep instead of power off?

    Thanks,
    CB
     
  2. DeusInvictus7 macrumors 68020

    Joined:
    Aug 13, 2008
    Location:
    Kitchener, Ontario
    #2
    well the way that it is SUPPOSED to happen, is when it hits 0% it goes into sleep mode, using the "emergency" power to keep it in sleep...then after about 5 hours or so of it sleeping, it fully shuts off...at least thats what the apple support site tells you when calibrating the battery...
     
  3. ntrigue macrumors 68040

    ntrigue

    Joined:
    Jul 30, 2007
    #3
    You're being too OCD. When it says 1-2% you would shut the laptop and observe the 'breathing' for up to 5 hours. It is at this point that even the reserve has been spent.

    Sorta related. The iPhone. Do you kill the battery then allow it to auto-on when plugged-in or turn it off after it starts up when plugged-in?
     
  4. cricketbird thread starter macrumors member

    Joined:
    Feb 17, 2008
    #4
    clarification

    ntrigue and DeusInvictus7,

    I believe that it is indeed designed to sleep AFTER power gets low and BEFORE it goes completely dead from lack of power. Often, this is exactly what it does.

    However, what I'm talking about is that sometimes (but not all the time), it just immediately powers off completely, without sleeping first.

    I'm wondering what the deciding factors are, and if there is anything I can do to "help" it properly go to sleep (so that I can just plug it in and resume working), rather than having it totally die on me (and take unsaved work with it - and yes, it is warning me properly about 5 minutes beforehand).

    Thanks,
    CB
     
  5. misterredman macrumors 6502a

    misterredman

    Joined:
    Oct 3, 2007
    #5
    You need to calibrate the battery, so that the mac knows exactly how much charge is left. The procedure is described here:

    http://docs.info.apple.com/article.html?path=Mac/10.5/en/9036.html

    Step 5 is very important.

    If your mac shutdown earlier the problem is in fact that the computer thinks there is still enough charge left, so it doesn't put the mac to sleep. But the truth is the charge is so low that the system shutdown.

    When it does leave it for at least 5 hours. Better is to do it overnight. Then recharge.
     
  6. ntrigue macrumors 68040

    ntrigue

    Joined:
    Jul 30, 2007
    #6
    +1 you're laptop thinks it has 3% when it has zero life the very reason to calibrate. Just sleep it sooner and wait longer until you plug it in.
     

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