Auto-brightness ON: Reduce battery life?

Discussion in 'iPhone' started by daonesteven, May 28, 2009.

  1. daonesteven macrumors 6502

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    Baltimore, MD
    #1
    I've tried to do google searches as well as search MR forums about this topic, it's like literally 50/50 on whether people think it saves battery life to turn it on or off.

    Anyone know the real verdict, if I really don't care so much about having it auto dim or bright?
     
  2. jsw Moderator emeritus

    jsw

    Joined:
    Mar 16, 2004
    Location:
    Andover, MA
    #2
    I think the most accurate statement is that, with it off, battery life is more deterministic, since the screen is always at a given brightness level.

    With it on, it depends on whether the phone is more often in a dim environment or more often in a bright one. There's no way to say for everyone which way is best - it depends on where you use it.

    In general, the dimmer you keep it, the longer the battery lasts (obviously), but I suspect that the auto-dim provides more usefulness (it keeps it fairly constantly "dim" in varying lighting conditions) than it detracts from battery life by making the screen brighter outside.
     
  3. daonesteven thread starter macrumors 6502

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    #3
    Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5H11 Safari/525.20)

    So the auto brightness sensor itself doesn't at least drain battery as it does it's work?
     
  4. jsw Moderator emeritus

    jsw

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    Mar 16, 2004
    Location:
    Andover, MA
    #4
    AFAIK, the sensor is always working (and really just drains an infinitesimal amount of energy). It's just a question of whether the phone listens to it.
     
  5. Small White Car macrumors G4

    Small White Car

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    Aug 29, 2006
    Location:
    Washington DC
    #5
    Well, yeah, but the screen is a HUGE battery hog.

    I find that just about any time that I'm indoors my screen is being dimmed a noticeable amount by the auto-dimmer. There's no way that it's not making up for the energy the sensor is using.
     
  6. Dr. Cabrera macrumors 65816

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    Aug 25, 2008
    Location:
    Los Angeles
    #6
    the sensor being on uses such a minuscule amount of battery it's a non issue.

    If you want maximum battery life, turn off auto brightness and set it to 0%
    If you want to drain your batter the fastest turn off auto brightess and set it to 100%

    Every other setting is somewhere in between those two extremes


    Lets assume your brightness is set at 50%

    If you are in a dark environment all the time auto brightness will make the screen dimmer
    this will save you battery

    If you are in a bright environment all the time auto brightness will make the screen brighter.
    this will waste more battery


    I personally have my brightness all the way up + auto brightness ( so it dims it when I use it in bed)
     
  7. Warbrain macrumors 603

    Warbrain

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    Location:
    Chicago, IL
    #7
    I've always wonder this, especially when it is constantly changing. I've never taken the time to check it, though.
     
  8. JCastro macrumors 6502a

    Joined:
    Feb 12, 2008
    #8
    I have mine set the same way but it doesn't seem to dim in low light. I even try to cover the light sensor to see if it dims, but it doesn't. :(
     
  9. matttye macrumors 601

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    Mar 25, 2009
    Location:
    Lincoln, England
    #9
    That doesn't make any sense, you have it backwards.

    In a dark environment auto-brightness will make the screen brighter, to make up for the lack of lighting in the area, so that you can see the screen.

    In a bright environment auto-brightness will make the screen dimmer, as there is plenty of light shining on the screen anyway.
     
  10. Tom B. macrumors 65816

    Tom B.

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    London
    #10
    He was right. You have it backwards.
     
  11. Dr. Cabrera macrumors 65816

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    Los Angeles
    #11
    [​IMG]

    please think (or do the research) before posting your own ideas as fact
     
  12. brvheart macrumors 6502

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    Dec 3, 2007
    #12
    +1 - the iphone is the same as the Mac Books - and most other sensor based optic screens - lower the light, the screen dims, brighten the light - the screen glows brighter....
     
  13. JCastro macrumors 6502a

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    Feb 12, 2008
    #13
    OMG!!! That is funny. You are right though!

    Lower light = Dim the Backlight
    Brighter light = brighter backlight
     
  14. matttye macrumors 601

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    Mar 25, 2009
    Location:
    Lincoln, England
    #14
    That makes very little sense to me, but if this many people are disagreeing with me I guess I have it wrong :D
     
  15. thisisarcadia macrumors 6502

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    Jun 26, 2008
    Location:
    New Orleans, LA
    #15
    i keep my brightness kind of low but to the point where i can see it good in the dark and in the sun! But when i first got it i had it all the way up and the battery would be dead in like 5 hours
     
  16. BNZ1 macrumors regular

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    Nov 11, 2008
    Location:
    London
    #16
    Give us an F...

    Thank you for your fail, I love the explanations :cool:
     
  17. daonesteven thread starter macrumors 6502

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    Aug 7, 2007
    Location:
    Baltimore, MD
    #17
    It definitely sounds counter-intuitive, but if you really think about it, it makes more sense. In bright light situations (like a sunny day outside), it's not so much that outside light conditions will help illuminate and make your screen more visible, but it will most likely overpower its current brightness (glare) and force the iphone to make it even brighter to allow you to see it.

    In dark situations it's easier to understand because you don't need the same amount of brightness to be able to see the screen so it'll dim it and still allow visibility.
     
  18. Small White Car macrumors G4

    Small White Car

    Joined:
    Aug 29, 2006
    Location:
    Washington DC
    #18
    Do you have an iPhone? (Or a laptop?)

    Turn auto-brighness OFF so you can manually control it.

    Then, go outside on a bright, sunny day. Set the brightness at 0%. Then set it at 100%.

    Then come back and tell us which one you thought was easier to use. I think you'll understand then! :)
     
  19. superxero3 macrumors regular

    Joined:
    Oct 15, 2008
    #19
    imagine you were in a very dark room, would you want your iphone to get even brighter than it normally is? I would think not, that screen can be blinding in a dark environment. So, in a dark room, it gets dimmer, and vice versa.
     

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