99% battery

Discussion in 'MacBook Pro' started by ViciousShadow21, Apr 5, 2009.

  1. ViciousShadow21 macrumors 68020

    ViciousShadow21

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    #1
    couldnt find any info on this.

    what does it mean when the battery % is stuck on 99%? i tried draining it then bringing it back up, but still stops on 99%.
     
  2. AppleNewton macrumors 68000

    AppleNewton

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  3. Warranty Voider macrumors 6502

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    #3
    Usually calibrating fixes it for me. But does that 1% of battery actually matter to you? Thats gotta be only a couple minutes more of run time. :rolleyes:
     
  4. ViciousShadow21 thread starter macrumors 68020

    ViciousShadow21

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    it's not that. i read on battery university that if this is happening on a li-ion battery that it means that the power adaptor is "cooking" the battery. basically when the computer knows that the battery is at 100% it lessens the output from the adaptor. i dunno, maybe i am just being paranoid haha.
     
  5. brop52 macrumors 68000

    brop52

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    #5
    It stops charging at 100%. It will begin charging again when it drops to 95%. It does this to prevent overcharging.

    If you think you have a problem then reset the SMC by shutting down, unplugging the AC, taking out the battery, and holding down the power for five seconds. You should also fully calibrate by charging fully and leaving charged for two hours, discharging fully and leaving discharged for five hours, and then fully charging. Calibrate every 2 months for best accuracy.
     
  6. ViciousShadow21 thread starter macrumors 68020

    ViciousShadow21

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    #6
    huh didnt know that. that's a good feature.

    i did reset the SMC and did a calibration about 2 days ago so i know it's no that. but i think you solved it. thanks.
     
  7. kastenbrust macrumors 68030

    kastenbrust

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    #7
    He's right but its not to prevent overcharging, thats wrong. Its because your power adaptor cant always provide all the power your Macbook Pro needs, so sometimes it draws power from both the magsafe adaptor and the battery, especially during performing CPU instensive tasks, such as any video work, gaming or watching flash videos (youtube etc) online, and then when it drops to 95% it starts charging the battery again. This is well documented on the Apple support site, and is why you should never remove your battery and run your Macbook Pro simply from the power adaptor. If you do that you'll underclock the processor by 50%, and shut down one processor core.
     
  8. brop52 macrumors 68000

    brop52

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    #8
    If I'm wrong then what Apple says about the issue is also wrong. They say it is to prolong the lifespan of the battery. It is all about heat when it gets near 100%. Read the kb article. I'm not saying you are incorrect about the computer needing more power than the magsafe can offer because that is also true. But that is not just between 95-100%.
     
  9. macgrl macrumors 65816

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    #9
    Mine only goes up to 99% too. Never really bothered me. I wouldn't worry too much about it
     

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