iPhone 7 Battery issues

iPhone 7.

Each day battery uses about 50% of a full charge before retiring for the evening.

So when used it uses about 50% for a 16 hr period. Then in the next 3-4 hours it drains down to 1%.

I am trying to determine why so much battery usage in such a short period.

• Background App Refresh off.
• The battery health says it is 82% Maximum Capacity.

Anybody have any ideas on why it would drain so fast when it is not in use?

Is the battery going out?

Could it be a rogue app?

Any suggestions would be greatly appreciated.