Oreo

[TheOtherBill]

Despite multiple cache wipes and 2 factory resets Android System still uses more battery than the screen does! Started with the Oreo update and I've tried everything google search can show me to fix it. It seems there's a lot of people with S7 (not just the Active) that have the same problem. I'm looking at rolling back to Nougat (v7) now, Oreo has been nothing but a problem.

 

[hellosailor]

It is possible for an OTA to quietly mangle everything on a phone.
I was really amazed when I downloaded a free trial of GlassWire, which sits in the background and reports every task that reaches out over the Wifi or cellular connection--secretly stealing power. That's a good way to see one major source of power drains. I'm also (no longer) constantly amazed at the Amazon apps, where every upgrade turns on new notifications and finds new ways to check for updates, all by itself, even when you've previously turned them off.