This might also be a fault of iOS 10. I used to charge my 5s once a week, but since installing iOS 10 I need to charge once a day. I've even turned off Background App Refresh and it still doesn't matter. The culprit was the Music app which I ended up removing (thank God we can now remove stock apps). The funny thing is that I never sync/load ANY music on my Phone... I've never even opened the Music app. But, for some reason the Music app takes 90% of my battery every day, even though I don't use it and nothing is playing (the app isn't even open). I've restored twice and done 2 fresh installs and the Music app drains my battery even though there is no music on my device, I do not have a Music subscription, and I've never opened the Music app (except to try and turn off settings). I have to remove the App entirely to get my battery to act normally. I never had any problems with my phone before iOS 10.