I had a problem with mine the other night too, I charged it, took it off the charger at 100% and 15 mins later it was down to 91 % without being used. Within two hours it was down to 31% and extremely hot with no use. When I checked what was using the battery it showed android os . I did a factory reset and the phone has amazing battery life again!!!
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Samsung Galaxy S3 White Virgin
samsung infuse 4g " a lot a screen real estate"
super F 2.2 froyo test 3 w/ danger SPL unlocked
50 apps 73mb internal memory
Overclocked Cpu @ 528 mhz