if I connect two electronic devices via USB-C how is the source and the sink determined for charging?

Question

if I connect two electronic devices via USB-C how is the source and the sink determined for charging?

In: 78

Answer 1

Software.

SmartPhones usually have some options to allow “reverse charging”.

A Power Supply only negotiate charging.

A Laptop can do both: if connected to a power supply, it charges from the power supply. If connected to a smartphone, it charges the smartphone.

If you connect two laptops? well.. I never tried, but some of them have a “charge equalizing function”, where the most-charged charges the lowest-charged.