I had the same problem with the battery progressively draining, even when on charge but not in use.
Possibly relevant for a solution:
- This problem began 👉🏼 after I updated to IOs 18.2.1 (I use an iPadPro).
- I had not changed the charger or cable since I bought the ipad, and it had charged fine prior to that. (So this is a new thing, related time wise to the system update)
- I turned off all apps and tried rebooting on a number of occasions. That did not help.
- The battery very slowly drained even when on charge and not in use (and to my knowledge no apps were on) overnight.
- Then I changed the charger to two different 20 W chargers. No joy.
- Then I changed the cable. No joy.
- A possible solution came from a different question from someone using IOS 17 (so this may not be system update dependant.
- ‼️In that thread someone recommended going to settings under Face ID, where believe it or not resides the setting to turn on accessories when the device is locked. It turns out the charger and cables are regarded as accessories. The person suggested turning on the option to use accessories when the device is locked, and someone else added the option to reboot it twice after.‼️
- Once I changed the setting and rebooted twice, it started to charge slowly again. (I have not had a chance to see what it does when plugged in, but turned off).
👉🏼 Update in background
Something else possibly relevant - even though there are only a few things I allow to update in background - some other apps seem to have update in background on - but the option to turn this off is greyed (lighted green colour) out, so I can’t change it. Is this one of the factors adding to battery drain, and how can it be fixed.
👉🏼 I’d suggest you also check your notification options. Are notifications contributing to battery drain, even when the device is off? (I greatly limit notifications for that reason).
👉🏼 I’d suggest you also check what you’ve allowed Apple’s SIRI and it’s other AI program to do.
I had them turned off and presume they were off (because I don’t want the drain on the battery or stuff going on with my data which I am not aware of); but the battery slowly drained anyway.