Battery guage... seriously

Discussion in 'MacBook Pro' started by tunerX, Mar 25, 2012.

  1. tunerX Suspended

    tunerX

    Joined:
    Nov 5, 2009
    #1
    So I have noticed that after owning my MBP for two weeks that no matter how long I leave it plugged in the percentage indicator keeps dropping.

    On the first day it was at 100. Then over the course of a week it dropped to 99. Now it is at 97.

    I am now going through the calibration steps that say to run it down until it shuts down, then leave it in that state for 5 or more hours, then charge it until the little light turns green. I have never done this on any rechargeable device I have owned. But I figure that i need to do this since it says 97 instead of 100 percent.
     
  2. Erasmus, Mar 25, 2012
    Last edited: Mar 25, 2012

    Erasmus macrumors 68030

    Erasmus

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    Hiding from Omnius in Australia
    #2
    Your computer will not top up the battery until it drops to below 95%. It does this to reduce charging stress on the battery, extending its life.

    Furthermore, under heavy load, your computer will drain slightly more power than the mains power supply can provide. The extra power comes from the battery.

    Therefore your battery charge will very slowly drop over time until it falls below 95%, before fully recharging.

    (Waits for GGJstudios' "This will answer some, if not all of your battery questions" post...)
     
  3. shardey macrumors 6502a

    shardey

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    Jan 28, 2010
    #3
    If you are going to worry about anything, worry about how many charge cycles you have on your battery, and what the full charge capacity (in mAh) is.
     
  4. thundersteele macrumors 68030

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    Oct 19, 2011
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    Switzerland
    #4
    If the battery is between about 95% and 100%, it does not get charged. This is to avoid short charge cycles that are bad for the long term performance of the battery.

    If for some reason you want to see it fully charged, disconnect, let it drop to 90%, and reconnect it.

    As to why the battery might loose charge while connected:
    Under very heavy load, the MBPs consume slightly more power than the adapter can provide, and very slowly discharge the battery.
     
  5. tunerX, Mar 26, 2012
    Last edited by a moderator: Mar 26, 2012

    tunerX thread starter Suspended

    tunerX

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    Nov 5, 2009
    #5
    OK, so was I supposed to do the battery conditioning?
     
  6. /user/me macrumors 6502

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    Feb 28, 2011
    #6
    If it's anything like the iPhone, the battery can't actually charge to 100%, but it's rather displayed as 100% for the user to feel satisfied...
     
  7. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #7
    As others have stated, it's possible that during periods of high demand, your Mac draws power from both the AC adapter and the battery, causing the charge to drop. Also, batteries are prevented from charging between 93% and 99%, to avoid short charge/discharge cycles. It's all quite normal. Finally, the built-in batteries in the newer Mac unibody notebooks come pre-calibrated and do not require regular calibration like the removable batteries.

    This should answer most, if not all, of your battery questions:
     
  8. Erasmus macrumors 68030

    Erasmus

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    #8
    Called it! :D
     
  9. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #9
    Of course, you're always welcome to post that yourself, rather than waiting for me, if you wish! :)
     
  10. Comeagain? macrumors 68020

    Comeagain?

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    #10
    Why don't you share you Text Edit files, and then you won't be the only person to post it!
     
  11. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #11
    I don't use TextEdit, but you can copy any of my posts. Just click Quote, then copy the text, including links. I'm not the only one, as many have quoted my posts to answer questions, most notably simsaladimbamba.
     
  12. tunerX thread starter Suspended

    tunerX

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    Nov 5, 2009
  13. Comeagain? macrumors 68020

    Comeagain?

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    Spokane, WA
    #13
    :confused:
     
  14. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #14
    Did you notice the date of the 2nd post you quoted? That was Dec, 2011. Here's one from Feb, 2012:
     

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