Question about battery usage

Discussion in 'MacBook Air' started by Stocks, Feb 5, 2015.

  1. Stocks macrumors member

    Joined:
    Feb 4, 2015
    #1
    Does connecting an external display use more battery power than normal use?

    I will often connect my 13" 2014 MBA to my 1080p TV via HDMI and watch 2 hours of Hulu while the laptop is on battery power. I keep the MBA display on during this time.

    After 2 hours I always have 50% battery life left, give or take 5%.

    I thought that I was supposed to get 12 hours?
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Yes, running an external display, drive or other plugged in peripherals consumes more power, which is why Apple recommends that you run on AC power when doing so. Apple states that you can get up to 12 hours. They don't guarantee you will get that much time out of a charge. How long you can run on battery is completely dependent on your settings, configuration and current workload, which can vary greatly.

    There are many factors that impact your battery life. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.
    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. Natzoo macrumors 65816

    Natzoo

    Joined:
    Sep 16, 2014
    Location:
    Not sure where i am
    #3
    You will get the full 12 hours if you don't use much apps and your brightness isnt full. Apple calculates the battery by on low brightness and low usage (or i think it is)
     
  4. Stocks thread starter macrumors member

    Joined:
    Feb 4, 2015
    #4
    Apple says 12 hours of movie playback which is why I found it odd to only get 4 hours. I didn't think connecting it to a TV would cut down the runtime so much.

    I know it's not an exact number they are giving us, but 12 is pretty far off from 4.
     
  5. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #5
    Yes, that's playback on your internal screen, not an external display.
     
  6. Stocks thread starter macrumors member

    Joined:
    Feb 4, 2015
    #6
    I've seen that thread and I've seen people linking to it in many other threads. I think one of the reasons why more people don't read the whole thread from the start is because it's 5 years old. People might not realize that you update the info. Maybe you should put the info into one new thread, just my opinion.
     
  7. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #7
    Thanks for the suggestion. Since there are thousands of links to that post, it's more effective to just keep updating it. I'll include a statement at the top to let people know that it's current information, despite the date of the original post.
     
  8. motrek macrumors 68020

    Joined:
    Sep 14, 2012
    #8
    The problem is not the external display, it's Hulu.

    Hulu has to download hundreds of K per second, which takes power, and it also uses Flash (or Silverlight?) to decode and display the video, which is catastrophically inefficient. Notice that when you're watching Hulu (or Amazon or Netflix), it uses almost all of a CPU core.

    When Apple says you can get 12 hours, they're talking about web browsing, where you download a few K once in a while and mostly just sit and look at web pages. They're not figuring for this kind of sustained load on the system.
     
  9. SFStateStudent macrumors 604

    SFStateStudent

    Joined:
    Aug 28, 2007
    Location:
    San Francisco California, USA
    #9
    Been averaging 8-11.5 hours doing internet run around and three pages open in Word & PowerPoint...not bad compared to 2-4 hours on my MacBook Pro 2.5GhZ! :cool:
     

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