Why does USB-C almost never work?

what is “PD”?

i have a 90 watt usb-c charger and it won;t charge a tiny cyansky M1R keychain light


USB-C is bidirectional. Both ends use the same connector. Thus the devices have to negotiate which end provides and which consumes power. By default none of them will provide any power until one says: “hey, give me some power.”

In the most simple case it is enough to add two resistors and the power supply outputs 5 V.

PD is a more complex protocol that includes some negotiation (voltage, current).

Many flashlight developers forget this detail and their flashlights won’t be able to receive any power via USB-C.

you mean the lights that do not work, are not doing the PD protocol?

i did notice they work on more ‘plain’ chargers - ie a normal charger with a rectangular plug on one end and USB-C on the other

those wouldn;t be doing “PD”

Manufacturers unfortunately forget to put 5.1 kohm resistors on the USB-C CC1 and CC2 pins to GND. A USB-C PD compliant charger (with a female USB-C port) looks for these and if they are present on the other end of the USB-C male to male cable it’ll put out 5V (3A max as per spec). For other voltages negotiation happens over these CC1/2 pins.

Unfortunately I’ve had to make a “trigger” adapter-thingy for such lights without a proper USB-C implementation. I made it with USB-C breakout boards with 5.1 kohm resistors available on Aliexpress.

This has nothing to do with PD. Your “plain chargers” with “rectangular plug”, which is a USB A connector, are always power source, thus they don’t have to negotiate who’s sender and who’s receiver.

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"Regular" USB chargers will always output 5v by default.

USB PD (Power Delivery) requires some sort of negotiation or at least a trigger before it'll output anything.

why would they [ cyansky for instance ] keep making products that do not charge on ‘normal’ USB-C?

seems like they have all known for 5 years at least what the issue is

Most of them (Astrolux and Sofirn, anyway) do ship an A to C cable. That always works.

Personally, I would rather have a C-shaped micro-usb than a regular micro-usb, because I really, really hate the micro-usb connector. So, even though it’s not perfect, it’s a big improvement, to me, anyway.

i guess

but i have these super high power chargers - expensive ones - and they don;t work

they also do not work for my modern, work, dell computer that has usb-c input