Alright peeps, ok I shall enlighten you of my experience. I too have had the dreaded batterygate effect on the iphone 4S since I had it brand new.
I restored it off my original Iphone 4 backup which in turn was from my Iphone 3G which was my first iphone. I too tried every thing I could to try and extend the battery life, I tried battery conditioning software, process killers, memory boosters, turned practically everything off, charged it from dead every couple of weeks...there ain't nothing I didn't try.
Almost two months down the line and I was ripping my hair still barely getting between 14-16 hours at best!!! The final straw was when I went to bed with 25% battery and after 6 hours sleep it had evidently died meaning my alarm did not go off, luckily it wasn't an important alarm but the phone was dead as a dodo!! So I phoned Apple and complained and they came up with an ingenius suggestion!! They told me to restore my phone back to factory settings and set it up as a new phone.......if that didn't work they were going to get me a new phone...as dubious as I was I did just that, I backed everything up and because of my icloud account I didn't lose any contacts/calenders notes or photos, but you do lose any settings on your phone and apps/games, which was a minor inconvenience. BUT....it has done the trick....it has worked a treat and now it is VASTLY improved!!! I finished the setup, put all my apps back on, music and stuff on left the settings cos I was knackered and went to bed with it fully charged.
I woke up and I couldn't believe my eyes....my battery was still well in the 90's with everything on full whack, all settings and on Wi-Fi etc!!! whether as before I would lose between 25-30% and that was with fine tuned battery saving settings. I have adjusted the settings and now almost 12 hours on with quite heavy use (tethering/light text/facebook and a 5 minute phone call) is still the best side of 50% a first!! By now I would be lucky to have about 20% left and that was with light use!!
So I urge you to try this little trick before righting it off!!!
process: transfer purchases, back up on itunes/icloud, back up all your photos/videos and then erase all contents and settings off the phone. When it resets setup as new phone, resync your icloud account which should restore your contacts etc, and then resync your apps and music!! All done!!
if it is makes no significant difference claim a new handset!