I had a similar issue however on my Galaxy S7. I came here while doing a quick Google search (no idea why I didn't come to the forums as I am a member, lol).
I found this article and a more specific one that outlines how to reduce battery drain aka increase battery life on the S7.
For me, I noticed that the article references the use of a task killer which I did install. However, in this thread, I noticed that there is advice against using such apps. On my S7, I used the task killer with no issue. But, when my brother installed the same on his Galaxy S6, it only made his problem worse.
I would think that the different software/hardware caused the difference between both our phones re-acting differently.
Other things that I did on my brother's S6 included,
- changing the GPS settings.
- Changing the sync intervals for emails.
- Changing the notification settings.
- Uninstalled the task killer.
- Reduced the brightness.
His S6 works better now. And, my S7 works great sans the task killer as well. However, works just as good with it installed.
