Good morning everybody, I'm trying to build a 5v solar panel charger for a smartphone like the one in the picture.
I would like to add also a 3.7v 3A Lipo battery with protection circuit to store energy when phone is not plugged.
Do you know an easy why to make the circuit only charge usb output when phone is plugged and battery when is not? (Possibly without using a manual switch).
I understood adding a resistor to the battery will make charge mainly the phone but will keep charging only partially the battery when phone is not plugged.
Basically I'm interested in knowing if there is a way to address circuit energy to a different output depending if a device is plugged to the usb.
Maybe a mosfet but not sure how.
Thanks in advance for your help and let me know if you need additional information and please forgive me also in advance for any mistake you can find.