How Much Does Brightness Affect Battery Life?

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How Much Does Brightness Affect Battery Life?

Hi all, just purchased a refurbished 13" Macbook Air 2012; I'm pretty psyched on it. My only issue is the battery, I never recieve the 7 hours Apple advertises!

My main question is: How Much Does Brightness Affect Battery Life?

-I like to keep my brightness at about 75%, I think I've been getting a little less than 5 hrs. Sound right?

-I've also tried out auto-brightness and I like it. How long have your batteries lasted on autobrightness? I've gone three hours straight so far and have 33% remaining- which would mean 4.5 hours. (If you do the math)

-Also- Are the "battery time remaining" estimates supposed to be accurate? Mines will jump around a lot, it'll often quote me 4h at 100% or 1h30 at 50%. But then change its mind pretty drastically.

-I'm basically just wondering if my battery is alright or if the wild swings in estimated life remaining and 5h- length are reason for concern. After all it is a refurbished model. Thanks

PS: My CPU is running @ 90%+ idle, typically only Google Chrome with +/-5 tabs open.

MacBook Pro with Retina display, OS X Mountain Lion (10.8.2)

Posted on Dec 12, 2012 7:15 PM

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Answer 1

Kappy

Level 10

361,995 points

Dec 12, 2012 7:34 PM in response to cwdudley

Don't know as I've never timed it, but Apple's advertised battery life is always based upon setting brightness to the lowest possible level for use. I wouldn't be surprised that battery time would be cut in half or more if you ran the computer at full brightness and turned off all energy saving features.

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