[cricalix]

Sometimes it's not the cable. Sometimes it's the sodding device. I have some IP60-something speakers for the shower. Write up says USB-C power. Brilliant says I, I've got plenty of good ones I use for charging laptops and other USB-C form factor accepting devices.

Sodding things only charge with their special USB-A to USB-C cable. They're in the bag labeled "cursed usb-c charge cables".

[linux_is_nice]

I do electronics professionally. This is likely because in order to save a bit on BOM costs, the device itself doesn't have the necessary pulldown resistors to signal to turn on VBUS.

USB-A has always-on VBUS while USB-C doesn't. Because the spec allows for always-on VBUS in a USB-A to USB-C cable, some devices just assume that they're always being powered by one of those cables.

[stephen_g]

I doubt it’s even saving cost, it’s just incompetence. It works with the USB A to C cable, so job done. They’ve probably never plugged it into a PD charger, and probably just copied the schematic from the last (defective) product and will copy and paste it into the next one too.

[cmiller1]

That is likely the case; cost savings, simplicity, etc. but the end result is USB-C does not "just work" for most consumers.

[Gigachad]

It's because they are straight up defective. The USB-C spec is pretty clear in that the power pins have 0v until you signal for a voltage. This isn't a failure of USB-C, you should just return defective devices to the OEM.

Thankfully this defect is becoming less common outside of temu junk.

[ssl-3]

That's because they didn't implement USB C correctly. Maybe it was to save less than a penny on the BOM, maybe it was arrogance ("it works for me! send it!"), or maybe it was something else. Whatever the reason, they didn't do it right.

By standard, USB C provides no power at all unless the device being powered follows the rules. They're easy rules to follow. The minimum viable way of doing it right requires just two tiny resistors inside of the device.

[chaz6]

It is not ideal, but you can buy C-to-C adapters with the resistors to force the charger to supply 5V.

https://www.aliexpress.com/item/1005012247371267.html

[thenthenthen]

I have a water pump like that, the reason: they have omitted the 5.1k resistors…

[notatoad]

you'll never guess what solution i'd suggest for that specific problem...

[cricalix]

Change the device? It works fine. The cable is labeled. I know where to find it. I'm not throwing away perfectly otherwise-good hardware because of that.