Solved my battery drainage issues.
What a lot of people are missing is iCloud and devices associated to your iCloud account. It can put a hit on your battery.
Perform the following:
- Go to Settings - iCloud - select your account (very top selection) - Devices - remove all associated devices to your account. you may even see devices that you no longer use.
- Go Settings - iCloud - disable iCloud Drive, Mail, Safari, Home, Notes, Keychain, and Backup
- Settings - iCloud - Share My Location - Disable Share my Location. Remove all associated devices for share my location as well under 'From' by swiping left and deleting each device
- Settings - Privacy - Location Services - System Services - Disable HomeKit, Location-Based Apple Ads, Location-Based Suggestions, Share My Location, and Disable Frequent Locations. Disable everything in Product Improvement
- Settings - Privacy - Advertising - Enable Limit Ad Tracking
- Settings - Sound & Haptics - Disable System Haptics at the bottom
- Settings - Photos & Camera - disable iCloud Photo Library, and iCloud Photo Sharing
- If you want, go to Settings - General - Background App Refresh and completely disable the feature
Guarantee you will get improvement in battery life after performing all of the above.