SO ever since iOS 7.1 my iPhone 5 battery had pretty much reduced it's self to about 4-5 hours no matter if I was using it or not. Same problem as the rest of you I think.
Any ways after trying EVERYTHING apart from restore as new everything was getting worse. I gave in and followed the instructions as posted by toneaikue. Really didn't think it was going to do anything but after a week now my battery is back to normal. Gone from 4-5 hours with little to no use all the way to 12 hours with heavy use an today managed 23 hours with little use.
I Did run into ine problem in the restore though. I used iTunes and backed up to my computer as well as iCloud. i could just not restore data from my computer to the phone. It would say it's doing it but nothing would happen. Just get stuck in preparing to copy items.
i managed to save myself by just restoring directly from iCloud.
MY biggest thanks thanks go to TONEAIKUE!!!!!!
Bottom line, after loading ios 8 my battery life went from 2 to 3 days to 1/2 day. I tried every suggestion posted here, no positive results. I contacted apple and they finally set me up with a supervisor who took the case. They kept telling me: (1). my battery was 2 years old, it was 2 years old with 7 and worked fine. (2) Turned everything off, still no luck, their response was to go through a check list (I had already done everything) and suggest I turn everything off, what good is the phone then. (3) Then ran a script remotely and stated the phone usage suggested it was still running while asleep. But it could no way be connected to ios 8, apple does not make mistakes.
SO: I started using the top power button to put it to sleep instead of just closing the cover. WOW battery lasted 3 days.
THEN I turned everything back on: still lasting 3 + days on one charge.
Reloaded all my apps: still hold strong.
Been several days now and I use the phone on a regular bases.
Does seem to drain the battery a little faster when used; I attribute that to the 2 weeks of draining and charging - took a little life out of the battery.
TRY putting your phone to sleep manually, worked wonders for me.
BEFORE: The usage indicated 80 to 90 % "home and lock screen".
NOW: The usage indicates 10% for "home and lock screen"
Hope this helps
i have heard doing a firmware reboot will fix this. i will try to post a link to the info tomorrow. seems to work wonders on the phones that have problems. my first iPhone 5 worked perfectly. i so loved that phone. after switching providers from sprint to at&t this phone will die at 25% then after plugging back in it will jump to 64% and after a sec of charging i can go another hour or two. I don't know i am checking on this DFU or something like that firmware reboot. before i make my choice.
ok. from what i have gathered (now mind you i am no expert, and do not claim to be) i have only worked hard at this because its a major problem on my end so i have done major research. this problem only seems to affect a small certain number of users. at first i thought it was a random set of users that was using 3rd party providers like straight talk cricket etc. yet i have recently seen a sprint customer with said problem. i do believe that this problem is occurring from a "jailbroke" firmware problem. (i do not know this for sure) the research that i have done is stating that when you bring your phone back to life "un jailbrake" your phone it still has a attachment to the firmware. some users have had success with the firmware reboot. (REMEMBER TO BACK UP YOUR PHONE) that said not all have had luck with this process. i have a link on my phone i will post it here in a second. WARNING: I've heard that if your phone has water damage before doing a firmware reboot may render your phone useless. so if you do not know the complete history of your phone you may wish to skip this and seek a different route.
Regarding #3 you are not quite right.
I bought a brand new iPhone 5 from apple store, and had this same problem i.e. after some time the battery started draining very fast even if you didn't use the iphone. I changed the battery hoping it will solve the problem, as apple stated they had battery issue, but the problem didn't go away it was a bit better the first 1-2 months and the problem started again.
I bought brand new iPhone 6 earlier this year, I hope I won't experience anything similar with this device.