New Battery Usage Tool

I've upgraded my iPhone 4S to iOS 9.1 on Thursday and everything seemed fine. This morning, however, my battery was draining really fast - 20% in 30 minutes so I started researching solutions. I'm still working on sorting the drain and have tried turning off and on, closing location services on a number of apps, closing all apps and reopening, I always have my brightness low but nothing has worked. Whilst researching I found there is a new Battery Usage tool and thought great I'll check that out to see what is using the battery and when I go into the battery screen I don't have that function only low power mode and battery percentage. Does anyone know why I don't have that new tool? Is it because I'm on a 4S and they have only given the older phone a few things? Any ideas for finding the Battery Usage tool or for increasing battery life would be really appreciated.