From doing some research it seems that the low battery level threshold is hardcoded in the framework (read as change it in the code, otherwise not user changeable). I assume that’s still the case.
There are apps out there that allow for setting your own alarms (when to stop or start charging) but still don’t change what’s set in the ROM.
Interestingly, check out this admittedly ancient discussion where someone on an S3 was able to change the threshold via notifications.
Thank you for your answer!
I’ll check with notifications, but I am not sure as what I had seen was a threshold choice of 15 or 25%.
It is indeed frustrating to see a “Power Off” message appear, while I can just plug the USB charger.
It would be nice to have a “20s countdown” or a last warning, letting you plug the charger immediately.