[KennyBlanken]

It's even worse. A 20W USB-PD charger might indeed put out 20W, but not at the voltage your device needs. It might put out 20W at one voltage, but only 10W at another.

The whole thing is a goddamn mess, and it's a mess because the alliance is a cartel, not an actually useful technical standards group. They're a bunch of fat swine contributing little to nothing but extorting licensing fees from everyone.

[crote]

This should never happen, provided everyone is actually following the specs.

If a charger outputs X W and a device needs Y W, for any X > Y it is guaranteed to output the voltage and current combination the device requires.

Every <=15W charger supplies 5V @ 3A, every 15-27W charger additionally supplies 9V up to 3A, every 27-45W charger additionally supplies 15V up to 3A, every 45W+ charger additionally supplies 20V up to 5A. A higher-power charger is therefore always a superset of a lower-power one. A charger may offer a variable voltage, but this variable voltage may not exceed the highest fixed voltage it offers. With the right cable, it may offer currents above 3A for lower voltages.

Devices are required to be able to charge from any charger providing at least the device's power rating, and it should even provide a similar user experience. It is not allowed to depend on the optional variable voltage or higher current a charger may offer.

Really, the USB PD specifications are fine. There is nothing wrong with them - except perhaps the fact that they are over 650 pages long. If you run into issues with USB-C charging, it is almost always caused by either the device or the charger manufacturer simply not following the damn specs.

[gumby]

I only remember a couple of gross violations, both in the early days: apple macbook charger and the Nintendo switch.

I think things have quieted down since. Of course that is due to the limited choice in chipsets (cartel? Or just bc nobody wants to design a complex, low margin part?). But nowadays dodgy mfrs can compete on who can electrocute or set alight the customer to save a couple of pennies, but the protocol conformance will be outsourced.

[sixothree]

For the last 5 or 10 years, USB has seemed like a standard designed to make you purchase more than what you need. Whether it's the capability of the cable or the number of cables (through trying to rectify disappointing purchases). I'm sick of everything they are.

[gumby]

I only buy the maximal cables as the other family members in the house assume all cables are equivalent. So I have to ensure that is true. Grr!

[bjoli]

Oh, but USB-PD 3.0 with PPS got rid of fixed profiles. Not the charger and chargee negotiate a voltage between 3.3 and 20V.

I wonder how they'll screw up that branding...

[gumby]

From the article they just label the maximum power, which the author called “speed”.