I earlier resolved the battery problem by disabling "push" email. I've installed the 6.1.3 update and reenabled push, and the phone continues to be normal for power consumption. Odd that Apple makes no mention of 6.1.3 resolving this issue for some users. Maybe the problem was resolved by other means.
I have the same problem as well.... Battery drains to fast and mind you, the phone was just a week old.... And I did what my friend told me..
Turn OFF Siri if not needed
Turn OFF EQ on Music because that too can consume a lot of power..
Decrease Notifications on your Notification bar or simply disable apps, not so important apps
Time Zone Auto Update - Disable as well or manual
and the basic - do not set the autobrightness of your iphone to auto, set it manually and decrease the brightness
I did all of that and well.. I can use my I5 for 12 hours if I use a 3G or a wifi and almost 24 hrs with no 3g/wifi...