I have a few related questions. All are related to charging the M5StickC, JoyC and RoverC and their drain during use. Given that RoverC and JoyC need an M5Stick to be connected to be charged and all have the devices have batteries in them and the batteries in each set (M5StickC paired with either JoyC or RoverC) differ in capacity. How Do We know:

1. State of Charge of the batteries in either set?
2. When To disconnect the charger? (batteries fully charged) and
3. Which of the two batteries in each set is being drained during use( M5Stick's or Hat's)?