Should i trust my batteries "time remaining"?

Discussion in 'MacBook Pro' started by jordanf1end, Nov 11, 2010.

  1. jordanf1end macrumors newbie

    Jul 5, 2010
    So im a new mac user and had a question about battery life. i did all the things apple says to insure a longer life such as calibration of the battery, using it at half brightness, turning off blue tooth, half volume etc. but i notice that when i plug out my charger it will estimate time remaining as 8 hours or so but like 2 minute later it will go down to 6 hours and fluctuate between 5-8 throughout the time using it. what gives?
  2. miles01110 macrumors Core


    Jul 24, 2006
    The Ivory Tower (I'm not coming down)
    Time remaining depends on usage. If you are playing Starcraft II, for example, it will report less time remaining because Starcraft II requires heavier CPU usage. If you quit Starcraft II and start reading your e-mail the time remaining will increase, as that doesn't take much at all.
  3. Hisdem macrumors 6502a


    Jul 3, 2010
    Boca Raton, FL
    It will fluctuate based on your usage. Unless you are keeping CPU activity steady for a long time, it will vary every time it refreshes. Just don't worry. If it keeps changing from 5 to 8 hours, for example, you could expect something in between those two. Assuming you are not using the same features constantly, that is.
  4. GGJstudios macrumors Westmere


    May 16, 2008
  5. ryannazaretian macrumors 6502a


    Sep 21, 2008
    Warning: Technical content below!

    Basically, the laptop has built in current sensors and an estimation of how much charge is left in the battery (in milliamp hours). So if you are currently pulling 1A out of a 12000mAh battery, it would estimate you to have 12 hours remaining.

    Of course, the laptop does not constantly pull 1A. It can range anywhere from 1A to something like 8A or even higher in extreme cases. So, dim screen, WiFi off, and typing something in Text Edit... your computer may pull something like 1.1A and last all day... but then you want to play that new fancy 3D game you got.

    So you turn up your screen brightness all the way, switch to your dedicated card, and since it's no fun to play alone, you turn on the WiFi and connect up your Bluetooth headphones to your laptop. Fans start whirring, the thing is really cooking now! You're pulling 9A from that poor 12000mAh battery. You're remaining battery time now went from 11 hours down to 1.3 hours!
  6. BenFL macrumors member

    Aug 11, 2010

    Great answer!
  7. jordanf1end thread starter macrumors newbie

    Jul 5, 2010

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