Do you have an exchange email account? outlook/gmail?
If so delete the account - then do a reset - hold down the home/sleep button together until you see the apple logo and thne release, then wait for the phone to boot back up.
then install the account again. Then let your phone die out and then let it fully charge undisturbed. Then see how the battery life is.
Another you can try is settings - general - reset - reset network settings.
You will have to enter password for known wifi again.