For the past two or three months, my Galaxy SIII has been getting horrendous battery life. Off the charger at 8 or 9 am, and by 3 or 4 pm, my battery warning would be coming on, saying less than 30% left, and I would have to charge it by 6 or 7 to keep it from shutting down. I work out of my house, and don't use the phone a lot. I started using Batteryguru about two weeks ago, and after a few days, it seemed to analyze my phone well. I am now getting battery left of 70+% at 4 or 5 pm, and my use hasn't changed. I too have been skeptical about battery apps, but this one seems to really work.