There is nothing more to say. The parts operate as described by the seller.
Red LED indicates load, the other fully.
I do not understand what the previous speaker said with balances and multiple cells.
The device is a 3.7 volt cell and not for several
(2S = 7.4 volts, 3 S = 11.2 volts and so on.)
For this you need a charger with balancer.
One should already read what you are buying and not realize his ignorance in false expectations.
Best regards
