Hi. Allthough i have an S3 LTE. And i have had terrible battery drain.
I managed to get rid of the battery drain, by changing to the lockscreen where you draw a pattern between dots.
Then I disabled messafes from apps (can be located in apps manager in settings).
Then i have disabled all synchronisation in the account settings. Google, outlook and so forth.
Then i have set the screenbrightness to aprox 10%, disabled all smartstuff. Like smartstay and stuff.
Then finally I have choosen a black only background image for the home screen and only chosen one widget. Wich is a digital clock. One of those without weather.
After that. I turned off my phone, and took out the battery for a half minnute.
Inserted it again and restarted the phone.
Then i did a factory reset, and made the same settings once again.
Now I have 10 hours on hard usage. More than 24 hours if i only make a 5 minute call and 10 texts. On pure standby, not using the phone at all. I get about 48 hours.
At this moment. I am trying out one or two things at a time to see what drains my battery heavily.
My bet. Is that samsungs swipe lockscren (the one that makes this fluid water sound and visual effect) is a heavy battery hog on S3 and other devices like this.