4. Is it capable of charging this device?
5. Is it capable of charging devices when plugged into this charger?
6. If it can charge this combination of things, what wattage can it charge at?
5. Is it capable of charging devices when plugged into this charger?
6. If it can charge this combination of things, what wattage can it charge at?
5. It depends, but the output capacity is printed on the power supply[0]. (Compare to USB-A, where the most you could do is 12W.)
6. The minimum of the cable (60W for any cable, 100W for some cables, 240W for a very few[1]) and the charger
[0] Annoyingly, this problem is compounded when using a power supply that can output (say) 100W on one USB-C port, but when both are used, the limit on the two ports is 60W / 40W.
[1] There are vanishingly few products (power supplies, cables, and devices) that support USB EPR. If you have one of these, just use the power supply and cable the device came with; this is no worse a situation than with devices that used proprietary power cables.
Speaking of which, every time I ask the question about “tell me just from looking at a USB C cord…”, I learn something new.
Plugging it in would probably be a good start. I can't name a single time where I've ever mistakenly identified a USB-C cable. Sometimes I've plugged it in when it wasn't connected to the wall, but I think worrying about non-compliant USB-C cables is no more relevant than caring about non-MFI certified Lightning cables.
99% of people only care about power (and optionally data), so that's what the spec focuses on.
Regardless, the fact that DP-Alt-Mode exists is not a refutation of the base USB-C spec. You're either spec compliant or you're not; same as Lightning without the license fee.
0: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...
Some “low wattage” specification USB-C devices are compliant with USB-C but are only compatible with USB-A power bricks because thet require 5V:
https://www.reddit.com/r/UsbCHardware/comments/c3q4s6/why_do...
Some USB-C cables are only 31 watts, and some devices can’t charge with less than 60W:
https://www.macworld.com/article/234030/how-to-tell-whether-...
Example brands from the above two links include JBL, Schooshe, and Apple.
I’ve hit similar problems with all my USB-C devices.
https://hackaday.com/2022/12/27/all-about-usb-c-illegal-adap...
There is a certain combination of cable+adapter+device that can ruin your device. I don’t remember the details. I heard about it on the Accidental Tech Podcast
This is because they are not USB-C compliant, despite physically featuring a USB-C port. The USB-C spec calls for any USB-C sink (i.e. device that consumes power) to include a pull-down resistor (Rd in the diagram on page 4: https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf?ts=169690039...)
Devices that do not include this resistor, and are therefore unable to be powered with a USB-C to USB-C cable, are noncompliant and should not exist.
> Some USB-C cables are only 31 watts, and some devices can’t charge with less than 60W
As seen in [0], page 37, even USB 2.0 C-to-C cables will support USB-PD at 3A: https://host.zlsadesign.com/HJU_Drfba.png
The USB-PD handshake is performed independently of the cable, and uses the CC wire that is mandatory even in USB 2.0 C-to-C cables (page 76 of [0]): https://host.zlsadesign.com/Bk62vSMZp.png
You're right about the 60W point. Anecdotally, every device I've ever tried to charge has had no problems at 60W (although of course they'll charge more slowly than if they had 100W), but this is definitely not guaranteed.
0: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...