Does Adaptive Fast Charging work when the device (S9+) is off?
I reckon chances are it will not. There must be some kind of battery power management and bar an overheat warning the battery is a passive brick I muse...
I know it will charge faster when the phone is off but that is not my question.
Something I've never considered to be honest @Riik
I would not think so as the phone would typically charge faster when turned Off anyway.
The phone and charger are smart enough to know when to turn to trickle charging when the Battery hits 100% to stop any issues occurring.
🌈 Stay Safe & Stay Alert. 🌈
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.
According to a -very polite- Samsung robot, the phone manages the AFF as long as the battery is not completely depleted.
So, if the phone is off, it will AFF.
According to the robot the phone keeps a little power aside to perform some basic functions like keeping time, AFF and 'other stuff'.
This 'other stuff' opens a new can of worms...