Originally Posted by
noglider
USB-C can provide 5, 9, 15, or 20 volts. There is a protocol between the charger and the gadget so the gadget can request the voltage it wants. It might also be able to say how much current it wants. I don't know much, but I'm pretty sure what I wrote is correct.
I have some gadgets from 2020 or 2021 that charge with USB-C. If I give them more than 5 volts, they won't charge, so I need to use an old-style 5-volt charger with a A-to-C cable. Newer ones adapt to whatever the charger can deliver. My spouse just bought an iphone 15, Apple's first phone that charges by USB-C. It was interesting to see that it will take the (probably) 20 volts that a computer charger provides, and it works just fine.
I received my second USB-C gizmo (a Samsung Android phone) in the mail this past Friday. My first USB-C gizmo was a laptop a half year ago.
I put a watt meter on the line on my laptop. It was up at 20 volts, at times it uses a lots of watts. I just looked at it now, it is fluctuating from 11 to 18 watts as I type this. But my computer is not working very hard right now.
So, I have been forced to learn some of this stuff now that I own it. My new phone instructions said to charge it up before anything else, so plugged it in, screen said it was at 67 percent. I had a watt meter on the cable and it said it was drawing 17 or 18 watts initially.
I never had any USB-A devices draw as much as 2 amps at 5 volts, i.e. never had 10 or more watts on any of my older USB devices.
As these newer devices need more electronics to operate the more complex software, even if the electronics get more energy efficient I can see our power needs will only grow when bike touring.