Hello Basvg_,
It appears from your post that you are having an issue with your AirPods discharging while in their case.
Be sure that the operating system installed on the device being used is up to date.
Tap on Settings > Bluetooth > [AirPods Name] and check "Automatic Ear Detection". If disabled, enable it and test to see if the issue continues. If it is enabled, toggle it off then on and see if the issue remains.
Tap on Settings > Bluetooth > [AirPods Name] and check the status of "Connect to this iPhone". If set to "Automatically" change it to "When last connected to This iPhone" and test again.
Have a good day.