I had battery guru installed in both my s3 and my mom's and it completely devoured my battery. Mind you I have a 4400mah extended battery, before I installed it I was averaging around 2 days of battery life. Afterwards my battery wouldn't even last 8 hours. The app is supposed to monitor your actions and mimic them for the greatest battery life but it didn't work for me or my mom. Her s3 with the standard battery dropped from about 8 hours to 6 hours and still hasn't gone back up.
I'd be careful if you choose to use it, it killed my mom's battery.
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