To the OP, if you're actively using the phone with the screen on, battery life will suffer...but here's my advice:
1. Disable auto-brightness, and just set it to the lowest level that looks good to you
2. Turn off power saver. I know this sounds counter-productive, and frankly won't help your battery, but in my experience it doesn't really save that much and only cripples your device (if you leave CPU throttling turned on)
3. The real test is how much battery drains when phone is in "standby" (not being used). I leave virtually EVERYTHING on, and generally lose only 1-2%/hour. Get it to 100% before you go to bed, leave it unplugged, and see where it is the next morning...then report back.
EDIT: I say to test in standby because there are too many additional variables to judge "normal" battery life when in use.
Google now destroys battery life? Sad if true.. Never disabled on my S3 and it doesn't cause an issue... My drain is due to heavy usage which is expected.
Sent from my Sprint S3 using AC forums.
I wouldn't go as far as to say it "destroys" battery life, but because it's so location-intensive, it does consume a fair amount of power. Personally, I find it to be a neat feature, but also found I didn't really use it for that much more than a novelty, so I turned it off. If you use it, fine, but if not, you can definitely extend your battery life by turning it off.
thanks for answer , how can i turn off google now ? yes i ll try to take to tmobile store to change my batter , did they took the phone and check it ? or they directly give u the new battery ??
Go into Google Search (i.e. Google Now), then menu --> settings and turn it off.
But syncing is one of the best things about Android imo. Being able to do things on the computer and have it auto sync the to the phone.

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Sent from my Sprint S3 using AC forums.
Agree 100%. You can definitely get great battery life with this device without having to cripple basic functionality.
EDIT: Sorry for all the edits.