If I plug a 10ft USB cable from the laptop (USB A port) to a phone (USB C port), it doesn’t charge the phone. If I use a shorter USB cable, it works. But on a Lenovo laptop the 10ft cable does charge the phone. I’ve tried 3 different 10ft cables.
Any thoughts on what’s going on and what I can do about it?
Welcome to the forum.
If it works, it works, and that’s nice, but a laptop is not intended to be a power supply. Laptop USB ports are intended for communication. 10 feet is really long for a USB cable. All wires experience voltage drop, the longer a wire is and the thinner the wire is, the more voltage drop. My guess is that phone is more demanding with its voltage cutoff than other devices, and the voltage drop is just at the edge of what it wants. After 10 feet with those cables, it may only work with some devices that output slightly higher voltage. The USB spec says a port should supply between 4.75v and 5.25v, with the upper end increased to 5.5v with the release release of USB Type-C.