I've found this solution on different forums here and there, and tested by myself and it's working great. But I wanted to make a separate thread to help people find this solution easier. The speculation and theory: Post iOS 7, and perhaps only on the iPhones post 5, Apple introduced a new technology that helps you maintain a good connection at all times. When you have both cellular and wifi on and connected, and one of these signals is not perfectly strong, the other connection will "help" into the connection, therefore maintaining a connection at all times even though one of your wifi or cellular signal fluctuates. The problem here is, from what me and other people have speculated: If you have both cellular and wifi on, and one or even both connections are not strong enough or fluctuate a lot, then "out of kindness" your iPhone (post iOS 7) will activate and perhaps enhance BOTH signals in order to maintain a strong overall connection. The consequence is your battery drain much faster than before, because while in the past, with both signal connected, wifi would take stronger preference over cellular, effectively let the cellular part rest, now both wifi and cellular will work together and compensate for each other. Count in the basic signal enhancing function in case of weak coverage, and you'll have a potential 3X or 4X faster drainage with your battery. In my case: Before yesterday, and since the official iOS 7 release, my iPhone 5's battery would go down to 80% or something on each morning, and then it goes down by 1 or 2% each 3 minutes or so just messaging. After 3 hours or so it would be basically dry. I thought it was an aging battery problem, and on 1st of October I swapped for a new one due to LCD problem, so I thought that would fix that. To my disappointment the battery dies just as fast, if not faster. So since yesterday afternoon, I've decided to turn off cellular when I'm home (mind you, my 3G coverage at home is always only 3/5), and turn off wifi when going out. Since then my battery works much better, just like the expected 10%/hour drainage. Yesterday before sleep I charged it to 100% and after waking up it's 96%, and now its status is (after messaging, youtubing, surfing, and constant music playing): 70% Usage: 3 hours, 45 minutes Standby: 10 hours, 19 minutes TLDR; Turn off WIFI if you're using 3G/LTE. Turn off 3G/LTE if you're using WIFI. Don't use BOTH unless you have excellent connection with BOTH!