Battery level drops while plugged in

Discussion in 'MacBook' started by justusthane, Jul 6, 2008.

  1. justusthane macrumors newbie

    Jun 8, 2008
    Wisconsin, USA
    Hello. I have a brand new MacBook ( < 1 month old ).

    I usually leave it plugged in and sleeping on my desk, and open it up to use it. After about a day of this, it will still say the battery is fully charged, and the light on the MagSafe is green, but the batter display shows 99% (or 98%, 97%, 96%). If I unplug it and use it for a bit, and the plug it in again, the battery will charge back up to 100% (and then the whole process will begin again).

    I love my MacBook, and want to make sure this behavior is normal. Thanks!
  2. logana macrumors 65816


    Feb 4, 2006
    Yes - that what happens with mine too - so I guess it is normal.

    The charge drops away slowly to 96% then when it feels like it then it charges back up to 100%.

    Normal behaviour.....
  3. ki2594 macrumors 6502a

    Apr 12, 2008
    Carmel, IN.
    It's just sometimes fluctuates when figuring out the exact charge remaining within the battery. It shouldn't be a problem at all.

  4. wxboss67 macrumors newbie


    Jul 1, 2008
    This is normal for the percentages you've show - your Mac is fine :)
  5. scotty96LSC macrumors 65816


    Oct 24, 2007
    Charlotte, NC
    Always wondered about this. My MBP does this too.
  6. morrisman1 macrumors 6502

    you should approach your power company

    and get a refund on your power bill! you are contributing back to the national grid!

    on a more serious note, my macbook will only charge the battery if it is 95% or lower, its it is 96,97,98,99% then it will just power the laptop rather than charging the battery. i guess it just thinks that its charged enough. i only come across if i take it off power for 10 or so minutes and it drops to 98ish%.

    mine doesnt every drop the power level though.
  7. CalBoy macrumors 604


    May 21, 2007
    Indeed, all current Apple notebooks have this feature. The charger will not begin charging unless the battery has fallen below 95% in order to prevent cycles from being added repeatedly onto your lithium-ion battery.

    As your notebook sleeps at night (and during the day), a very small amount of power is used, and eventually, your notebook's battery will have consumed 5% of your maximum battery power. Only then will the charger kick in, for this prevents unnecessary charging when your computer isn't doing anything important.
  8. justusthane thread starter macrumors newbie

    Jun 8, 2008
    Wisconsin, USA
    Thanks for the great answers everyone! My worries have been abated.
  9. bigp9998 macrumors regular

    Dec 21, 2007
    I think it's considered bad for either the computer itself or, more likely, the battery to constantly charge, so they only let it charge if it gets below 95. Granted, every time you charge it, your overall health will go down just cuz it can't keep a charge as well as it used to.
  10. Machyper macrumors newbie

    Jul 6, 2008
    This is totally normal. Probably too much battery will blow up your computer!:D:D
  11. w00t951 macrumors 68000


    Jan 6, 2009
    Pittsburgh, PA

    Yeah... my MBP also does this, it's to regulate the battery cycles. The battery drops because the computer can't run off the wall adapter completely, and so it dips into the battery a bit when the power consumption is higher than the adapter can provide. :D Link to the Apple Support page is:

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