For instance, if you leave your phone charging all night (say 8 hours)… it stays at 100% for hours while continuing to be plugged up and charging. Where does this extra electricity go if the battery is already full?
In: 0
Nowhere.
The phone charge is really just a power supply in almost all phones. It has a constant voltage and can provide a max current. It is the phone that determines the current that is drawn. So when the battery is full only enough current to power the phone is drawn.
Compare to a wall outlet where the current is determined by what you connect, A 20W and 100W incandescent light connected to tow outlets will have a current that differs by a factor of 5 but the voltage is the sam for both.
You can have electronics that control, for example, the brightness of a lamp, and the current from the outlet will depend on the lamp’s brightness.
Tecnialy Li-ion charging is done with a constant voltage when the battery is above ~80% full and the current depends on the voltage difference between the battery and the charge circuit. That does require voltage conversion from the USB input voltage and practically is the same as the phone controlling the current to it.
Latest Answers