Battery calibration questions... please!

Discussion in 'MacBook Pro' started by lacereza, Nov 8, 2008.

  1. lacereza macrumors regular

    May 31, 2008
    I just got a replacement battery for my late 08 MBP. THe last one was draining very, very fast.

    So I charged it to 100%, let it drain until it went to sleep... but now I'm supposed to leave it off for five hours, and I need to use the computer! I took the battery out (after trying to turn it off using the power button) and connected the power cable, and expected it to start up from scratch, but I instead saw the 'coming out of hibernation' thing happening.

    1. Does the computer hold a little bit of charge somewhere other than the battery? How else could it manage to not shut down completely when I took the battery out?

    2. Is it all right to use the computer for the next five ours with battery out, or does it need to 'rest' in the computer for that time in order to calibrate properly?

  2. hari-bhari macrumors regular

    Jul 4, 2007
    the computer is entering 'safe sleep'. when you put the computer to sleep it writes the contents of the ram to the hard drive and then puts the computer to sleep maintaining power to the ram. as long as there is battery power left or you are on AC power, the computer will pop back to life immediately. however if there is a loss of power (aka disconnecting AC or pulling out the battery), then it will automatically revert to this 'safe sleep' and when you turn your computer back on it will pull the original RAM contents off of your hard drive and copy them back onto your ram. that is why you get that white overcast screen with the progress bar on the bottom. hope that helps.

    as far as not using your computer for 5 hours, i think you'll be fine. the new macbook pros seem to be going straight into hibernate mode when the battery is drained and there is no juice left for sleep mode anyways, meaning that the battery is fully drained and you can just plug it back in and use it. but leave the charger plugged in until the battery is fully charged which may take 4 hours or more
  3. GoCubsGo macrumors Nehalem


    Feb 19, 2005
    Pardon me for asking a silly question, but where did you read that you must not use the computer or battery for 5 hours after you fully discharge it?

    When you fully discharge there is a new sort of "deep sleep" mode the MB enters into. Once you plug the MB into the external power source you hit the power button whereby you see that status bar, the screen's colors are basically muted, and it'll start "waking" up. The colors will return and you can use your MB while you recharge your battery.

    Maybe this article will help you.
  4. Steve686 macrumors 68040


    Nov 13, 2007
    US>FL>Miami/Dade>Sunny Isles Beach>Condo
    The 5 hours guideline is on Apple's site. Here is the excerpt.

    PowerBook G4 (15-inch Double-Layer SD), MacBook (all models), MacBook Pro (all models), MacBook Pro (17-inch) (all models) and MacBook Air

    The battery calibration for the PowerBook G4 (15-inch Double-Layer SD) and any model of MacBook or MacBook Pro has been updated because of a new battery released with this computer. With these computers, follow these steps to calibrate your battery:

    1. Plug in the power adapter and fully charge your PowerBook's battery until the light ring or LED on the power adapter plug changes to green and the onscreen meter in the menu bar indicates that the battery is fully charged.
    2. Allow the battery to rest in the fully charged state for at least two hours. You may use your computer during this time as long as the adapter is plugged in.
    3. Disconnect the power adapter with the computer still on and start running the computer off battery power. You may use your computer during this time. When your battery gets low, you will see the low battery warning dialog on the screen.
    4. Continue to keep your computer on until it goes to sleep. Save all your work and close all applications when the battery gets very low, before the computer goes to sleep.
    5. Turn off the computer or allow it to sleep for five hours or more.
    6. Connect the power adapter and leave it connected until the battery is fully charged again.

    Tip: When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, with the safe sleep function introduced in the PowerBook G4 (15-inch Double-Layer SD) computers, the computer's memory contents have been saved to the hard drive. When power is restored, the computer returns itself to its pre-sleep state using the safe sleep image on the hard drive.
    Additional Information

    If you're not sure which model of PowerBook you have, see article 88248 to figure out which model you have.
  5. lacereza thread starter macrumors regular

    May 31, 2008
    Thanks for the replies.

    Yes, I know about the deep sleep mode, but on my previous Mac notebooks, removing the battery causes complete shutdown, with proper restart required if I take out the battery and plug in the power cable.

    In this case, I let the battery drain until deep sleep, took out the battery, plugged in the power cord, and then saw it wake from deep sleep, rather than start up fresh. I don't see how that could happen if the computer isn't storing some small amount of charge somewhere other than the battery.

    I just want to know if leaving the battery out for five hours will have the same effect as leaving it in the computer, disconnected and turned off, as per Apple's instructions.
  6. allanibanez macrumors regular

    Oct 11, 2008
    I did the battery callibration on my machine when i got it. I left it off for the 5hours once it had died and then did a full charge. I guess it is a pain when you want to use your computer, but it helps the battery abit in the long run.

    Presumably, taking the battery out will be fine for the 5 hour period because either way there will be not charge running through it. I'm not 100% sure however.
  7. duffyanneal macrumors 6502a


    Feb 5, 2008
    The idea behind the 5 hour sleep is to further drain the battery beyond what is possible with the machine powered up.
  8. Steve686 macrumors 68040


    Nov 13, 2007
    US>FL>Miami/Dade>Sunny Isles Beach>Condo
    Correct. The computer is still using battery cells while in the sleep mode. The 5 hours with the battery still connected ensures the battery is actually "dead", and no power is still available. This way the computer can actually "calibrate" how many cells(hence life) are being charged to full capacity from "zero".

    So if you want a correct calibration. leave the battery in when your computer enters sleep mode.

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