The home for all things iPhone on LW.
Rules:
What can be the reason that an iPhone SE 3rd gen. loses battery power significantly over night when it is completely shut down? The flight mode was activated before the shutdown. The device is brand new, battery capacity and health is on 100%, no background tasks are allowed. It is a replacement for the same model, which had the exact problem some weeks ago.
Even when I disable that function before powering off the phone looses energy. I found similar reports on the internet. A failing capacitor could be the reason.
If it’s brand new, it might be doing stuff in the background. I had a similar issue some time ago but eventually it went away.
Maybe some buggy app is causing it. Might be worth setting up as new instead of restoring from a backup.
Oops I just realised you meant when it was completely off - no idea what could be causing it. Are you in an extremely hot or cold climate ?
If it is completely shut down there should no third-party app do anything. Even when I switch off the Bluetooth beacon which helps to locate the phone when it is shut down there is this massive power loss.
I found similar reports on the internet, also from Android users. Most of them assume a failing capacitor on the main board. If this would be the case then it would happen the second time at a brand new iPhone.
Find my iPhone is still active when powering off the device, could be that? Which version of iOS are you running?