battery running out of power quickly since updating to 16.5 OS

Higher than usual battery utilisation is expected to occur for some hours, or possibly days, after performing a system software update. After updating, many background housekeeping processes will be running - including reindexing the file system. Nominal battery utilisation can be expected to return within a few days.

If you are experiencing very high battery utilisation, a process may have stalled. A forced-restart will usually clear a stuck/stalled process. To restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If the problems persists, you might be well advised to seek assistance to seek from Apple Support - and request a remote diagnostic test. You can contact the Support Team using the Support link at top-right or bottom-left of this page. 

Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad:

Genius Bar Reservation and Apple Support Options - Apple

Subsequent to the iOS/iPadOS 16.5 update, there is an issue with charging the iPad from USB Type-A Power Adapters, via the USB3 Camera Adapter - regardless of the Power Adapter’s power output.

The current workaround, pending a software update to fix the issue, is to use an Apple 20W USB-C Power Adapter with a USB-C to Lightning charging cable.