I have a few USB-C devices with their own chargers and I'm not sure if I can interchange them. What's confusing me is the different output values listed on the charger. From what I understand too high voltage can damage the device that is being charged and too low current can damage the charger/cable, while current above required is always fine (please correct me if I'm wrong).
For example my laptop charger can output: 20V=3.25A, 15V=3A, 9V=2A and 5V=2A. If I were to charge my power bank with it which accepts 5V=3A, 9V=2A and 15V=1.2A as input, could something go wrong? In this case if I were to plug in the power bank to my laptop charger how do I know that it's charging at the 15V=3A that it should and not at 20V?
On the other hand, if I were to charge my laptop with the same power bank (output: 5V=3A, 9V=2A, 15V=1.2A, same as input) could the power bank be damaged?
Best Answer
The USB-PD standard allows for multiple output voltages on USB-C devices, but every USB-C power supply must initially output 5V and communicate with the device on the other end. If the other device does not specifically ask the power supply to output more than 5V it will just continue to put out 5V and no more.