I bought an iphone 5 2 days ago and both days, the battery has drained to 20% in 12 hours.... I thought it was supposed to have 8 hours of talk time? I haven't even been talking on it. 2 calls... just texting. Is there a app killer app available?

A function may be ON that is unnecessary, these are very difficult to trouble shoot. Even simple things such as screen brightness uses battery. But the battery usage you have seems to be fairly good. If I can get through the day on a single charge this is the only convenience I need. Charge at night, use during the day, charge at night, happy.

I use an app called Caret. Tells u the apps running in the background. It will tell u if you close this app, how much more time u have.

but like what brad805 said, it doesnt look at brightness and others.

Well, i bought two iphone 5 for me and my wife...she used it for only 2 days and she gave it back to me complaining from the same problem and she went back to her 4S, i thought she was kidding until i used mine,,,oh my god, the battery does not last for more than 6 or 7 hours, even without making any calls. i was so happy with my previous 4S as i used to charge it at night and stay almost 2 days on a stand by before recharge it again. well, im done with apple, have an appointment today in apple store to return mine, and even if they give me 2 new ones, i will not even open them,,,, for sale right away.

Got 2 Apps for you to DL and try, watchs over your CPU % sees whats eating up battery/ memory

1) System Status( shows battery %, cpu %, network connections, memory usages/ %, what process are running

2) MyDataManger (incase you are eating thru data also, monitors very nicely well laid out)