Why does MacBook Pro battery charge drop the longer it is connected to the wall?

Discussion in 'MacBook Pro' started by logicstudiouser, Jun 19, 2015.

  1. logicstudiouser macrumors 6502

    logicstudiouser

    Joined:
    Feb 4, 2010
    #1
    I have a 17" MacBook Pro that I use as both a desktop and a portable computer.
    I will have days when I continue to work from my desk at home and the macbook pro could be plugged in for 5 days. I notice the longer I have my macbook pro plugged into the wall, the battery charge dips from 100% to 99 than 98 than 97. I have had it go all the way to 91% once.
    Why does it do this? Is this normal or is there something wrong with my battery?
    Btw, I had the battery replaced with a new official apple battery (not a generic third party battery), 8 months ago, so my cycle count is about 105 and in the 'System Information' app, my battery status shows up as 'normal'.
     
  2. snaky69 macrumors 603

    Joined:
    Mar 14, 2008
    #2
    Trickle charging and discharging to prevent "storing" the battery at 100% charge which is bad for it.

    Perfectly normal behaviour.
     

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