After every major Android update, operating system caches tend to get tangled leading to a number of known bad behaviors and battery eating is one of them.
Trying to chase down the problem with monitors is an exercise in futility because the OS is unstable and you may not get the truth. I've seen people not believe me and waste days thinking that they've solved the problem only to discover that they have to keep it up and play whack a mole.
This guide will walk you through the steps you really want to try. It says it's written for Lollipop, and that's because
@ironass updates it per phone and update but the steps are the same for you.
http://androidforums.com/threads/s5-lollipop-update-problems-dummies-guide.892800/#post-6840098
Read the first two posts before proceeding.
I recommend that you go right to clearing the main cache in post #1 - and if that fails to fix it, go to post #2 and backup, factory data reset, and restore your backup.
Also, if you're using the wifi smart switch feature from Samsung, turn it off.
Hope this helps.
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