Why does my newly charged MBP battery start at only 94% full?

Discussion in 'MacBook Pro' started by peanutismint, Apr 20, 2015.

  1. peanutismint macrumors 6502

    peanutismint

    Joined:
    Apr 4, 2007
    Location:
    Cardiff, UK
    #1
    I unplugged my MBP at home and just got it out to use away from a power supply, but having opened my lid, my battery (just disconnected from mains about 20 minutes ago) is showing as 94% remaining (rather than 100% or 99%).

    Is there any reason why it would start at this lower amount?
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    What was the charge level when you plugged it in? The battery may appear to stop charging between 93 percent and 99 percent, because the batteries are designed to avoid short discharge/charge cycles in order to prolong the overall life of the battery. Once the charge level drops below that range, it will charge when plugged in.

    It's also possible that some process is running that's drained your battery from 100% to 94% in 20 minutes. Check Activity Monitor to see what processes are or have been consuming energy.

    The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
     
  3. bobcan macrumors 6502a

    bobcan

    Joined:
    Jan 8, 2007
    Location:
    Sunny but Cold.. Canada
    #3
    Much as above, it will matter how long ago it was plugged in, and how much it was 'topped up' when last connected _ and bear in mind that although measuring actual voltage, the gauge is not unlike a Fuel Gauge in a car and NOT always that accurate, and seems to move erratically at times _ and also it is 'guessing what you do' sometimes based upon usage to come up with a 'time left', and will become far more accurate with sustained charge-discharge cycles (or at least my latest rMBP seems to) _ No matter what, I suspect it is not likely anything to worry about, much.. ;)
     

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