Why am I getting such terrible battery life out of my iPhone 4S ?

I just recently sold my iphone 4 which the battery life was superb from heavy usage - 8 hours usage with 20 hours standby. But I have recently bought and iPhone 4S 16gb and the battery is terrible, I get 4 hours usage time down to 20% from 100%, how can I help change this ??? My FaceTime,Siri, iMessage, Bluetooth are off