The actual working of red LED in Li-ion battery charger

[Abdulbadii]

How actually is the working of red LED in Li-ion battery charger, it's turned on when no current (open) and when prettty high current (is charging), then as current small i.e. the battery at max volt and full charged so current pretty low, the LED turns into green ?

 

[Externet]

The LED is lit by a microcontroller that manages the charging process and knows what is going on with currents, voltages and temperature by the way the designer of the circuit decided to behave. Not necessarily the way you think it works. Two or more different colored leds can be in the same package.
Look for schematics of lithium chargers.