This is something that I've been frustrated with for a while with my LG V10. First off, the phone is great, I love it, but I've had some issues with idle power drain where I cannot pinpoint exactly what app or setting is causing the battery to slowly bleed while the phone sits idle.
As an example, last night I charged the phone to 100% and unhooked it. This morning after I woke up and checked the phone (11 hours elapsed with essentially no use, no screen time etc), the battery level was at 58%. In the last three hours, 16% of the battery has been used. When I looked at the usage meter, the biggest culprit is the amorphous "Phone Idle" category.
I've gotten to the point now where I'm willing to do a factory reset, but before I do that I was wondering if there was anything else I could look into.
I didn't find the right solution from the internet.