# Does automatic brightness kill more battery than manually setting brightness?



## Kancerstick (Dec 25, 2011)

I've always been curious as to whether or not using auto-brightness taxes our phones more (using more resources) than manually setting brightness to about the same level.

So if im in an area for lets say 6+ hours at work, and the brightness never changes in my office. Theoretically auto brightness would kill more battery right?

I imagine with autobrightess, it needs to utilize the sensor on the phone, and more cpu cycles etc....

or am i just tripping out here?


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## gunderwear (Jan 26, 2012)

Kancerstick said:


> I've always been curious as to whether or not using auto-brightness taxes our phones more (using more resources) than manually setting brightness to about the same level.
> 
> So if im in an area for lets say 6+ hours at work, and the brightness never changes in my office. Theoretically auto brightness would kill more battery right?
> 
> ...


I am not a huge expert here. I totally get what you are saying and I would be curious to know the answer. My recommendation though would be to set the brightness to low while you are at work. That way the phone won't have to check or change anything and max brightness won't be on.


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## pmoradi2002 (Jan 7, 2012)

Most people are going to tell you to disable auto brightness and manually set it to 30%.

I did and I'm happy with it. Only downside is you can't see anything if you're out in the sun.


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## craigacgomez (Jan 17, 2012)

Well, yes, auto-brightness would drain more battery than manual brightness under most situations.

Consider this... when you set the phone to auto-brightness, the phone makes use of a sensor to judge the ambient (surroundings) brightness, then calculates (from a fixed set of values) what would be the optimum LCD brightness and then changes the brightness level. Everything that happens here takes up CPU cycles and hence, more battery would be used...

If brightness is manually set, the phone does not make use of any sensor or calculate the ambient brightness so it would consume less CPU cycles and hence less battery use.

Setting the brightness to the max at all times could make the above statement a moot point since max brightness means for power usage by the LCD and could basically mean more battery usage.

Most often, I believe that auto-brightness battery usage is quite minimal... considering the fact that ambient brightness does not fluctuate too much for a particular timeframe when your display is on... I've not noticed much difference in battery drain in some random tests...


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