Interesting battery life observations

Discussion in 'MacBook Pro' started by revelated, Sep 12, 2010.

  1. revelated macrumors 6502a

    revelated

    Joined:
    Jun 30, 2010
    #1
    I wonder if this nVidia chip is really more power hungry than I thought it was.

    Recently I was asked to actually give the Lord of the Rings trilogy a try. $3/per movie rental isn't bad, so I decided to give it a shot. I did the first two movies on my MacBook Pro 17", the third on the iPad, as a test of some of the claims that the iPad actually exceeded its rated battery life when playing videos.

    From a full charge the MBP was near dead after Fellowship of the Ring. Same result from Two Towers. This is with nothing else running or open, screen brightness three notches down from max, volume max.

    From a full charge the iPad was 30% down after Return of the King. That means that in theory, I could have watched all three movies at a total of around 10 hours and still had a little juice left. This is with screen brightness at around 75%, volume max.

    The question though is why? Does anyone know the true technical details behind this? I don't expect the MBP to run full screen videos for 10 hours, but I would have at least expected it to last the 6-7 it would take to watch Fellowship and Towers back-to-back. Next time I watch massive movies (like, never) I'll test with gfxCardStatus forcing the Intel GPU and see if it makes any appreciable difference.
     
  2. Constantine1337 macrumors 6502

    Joined:
    Dec 3, 2009
    #2
    This is for several reasons:
    1. Apple designed the A4 chip inside the iPad to fit its own needs (better power consumption)
    2. In the iPad, the internal system barely uses any power. Almost all of the battery power goes to the display. (Steve Jobs to Walt Mossberg after iPad introduction)
    3. You have a lot more backround processes running on the MacBook Pro than on an iPad
    4. You need way less power to power a "small" display such as iPads than to power a 17" FullHD one. Also remember that in your MacBook Pro the battery power also flows into a lot more RAM, full-scale GFX card, heat sensors, fans, bigger speakers etc.

    Proportionally, the iPad has bigger battery than the MacBook Pro.
     
  3. revelated thread starter macrumors 6502a

    revelated

    Joined:
    Jun 30, 2010
    #3
    What you say makes sense, thank you.
     
  4. ljx718 macrumors 6502

    Joined:
    Dec 13, 2008
    #4
    Even if nothing is running it still have to power all the components
     
  5. Abbe macrumors newbie

    Joined:
    May 6, 2010
    #5
    And remember that MacBook has to power the hard drive which is constantly spinnign and reading while playing back a movie (unless it has an SSD inside of course). The iPad has flash memory and that cuts power consumption by a great deal I would say.
     
  6. revelated thread starter macrumors 6502a

    revelated

    Joined:
    Jun 30, 2010
    #6
    Moot in my point as I'm running an SSD. But the concept of powering the fans and the high speed RAM as well as the GPUs make sense as to the cut.

    Makes me wonder though if Apple would ever consider a "Cinema Mode" in its MacBooks and MacBook Pros - basically, an A4 chip and whatever GPU the iPad has, off to the side and inactive until you run Front Row or watch movies in iTunes - assuming nothing else is running - in an effort to maximize battery life when just watching movies. That would be quite an awesome revision.
     

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