Latest iOS update is killing the battery on my iPhone 5, how do I go back to the old one?

Thank you for all if the information. The 6.1.3 update was actually the first one I ever did over wifi, so I'm going to do what you suggested to fix that. Right now, I've done everything else suggested and have had no change, so I'm willing to do a factory reset if it'll fix it.

Ok, just finished backing up and did the "reset all settings" first. I'll update in a couple hours. If it doesn't work, I'll do a complete factory reset and erase everything.

I might be jumping the gun here, but I think it worked!!! KevPan, thank you so much!! Everyone just kept telling me I must be doing something wrong or using it too much, so I was very happy to hear someone suggesting a real fix. It's been about 20 minutes since full charge right now and it's still at 100%. I used it for about 10 of those minutes, and I also left all the extra stuff on like bluetooth since the reset turned it all back on. Thank you again!!

I might be jumping the gun here, but I think it worked!!! KevPan, thank you so much!! Everyone just kept telling me I must be doing something wrong or using it too much, so I was very happy to hear someone suggesting a real fix. It's been about 20 minutes since full charge right now and it's still at 100%. I used it for about 10 of those minutes, and I also left all the extra stuff on like bluetooth since the reset turned it all back on. Thank you again!!