Enbies and Gentlequeers, may we present to you: the USB-C killer five thousand.

No power delivery, no negotiation, just 12V straight to VBUS

You surely wouldn't regret having a USB-C plug with 12V on VBUS around.

@derf That's right! It goes in the VBUS.

@jpm does this do fast charge?

@arichtman
It does drop a massive charge rather quickly.
@jpm

@derf Chuwi... I have some Chuwi Surface clone with a 12V PSU, USB-C without PD.
There seems to be a patten.
Label this cable with a warning!

@Exilsarahl @derf EU sagt es braucht USB-C, aber nur von der physischen Größe?

@kloenk @derf Du meinst, ein klassisches Beispiel für gut gemeint, aber nicht zuende gedacht?

@Exilsarahl @derf oder malicious compliance

@derf Can you actually do any USB killing with it? They should not be doing this, but any USB device should probably expect 20V on the input these days... and my guess is that many devices will tolerate 12V just ok.

@pavel @derf I have various earbuds and small torches that have the Type-C plug, but when I connect them to a good PD supply via a monitor, they only ever get 5V.

I imagine that adding PD capability to a small low power device is not worth the cost :-)

@pavel @derf anything that was a microusb design, now with a type-c port, will not survive it. plenty of them

@arcaneoverflow @derf Yeah, expected, and was not my point.

@whitequark @derf Why do you believe it will not survive 12V?

I guess you should not try, because it may be out of spec for the devices, but old Nokia phones were designed for 5V charging, but were actually designed to survive 15V IIRC according to service manuals.

I'd strongly suggest anything USB to survive 20V these days, and may guess is that a lot of hardware would actually survive.

@pavel @derf because I design electronics and know how it's put together? it's pretty normal to use components with absolute max rating of 6-7 V if you're not using USB-PD explicitly. it adds cost for very little gain, so it is generally not done

@pavel @derf anyway, you're welcome to take 10 random devices around you and subject them to this stress if you don't believe me lol

@pavel yeah, no, definitely don't try this.
proper USB-C negotiation chips will prevent this crap from doing any harm, but 90% of 5V devices have no Vbus MOSFETs, they just have the 2x 5.1kOhm resistors and that's it.

If you connect them to 12V, you'll let the magic smoke out. Quickly.

@pavel @derf We seem to have different points. Some people reading may not realise it's a very bad idea to stuff the wrong voltage into the charging port, just because it looks the same (which has previously been the point with USB Type-C, after all). Earbuds and torches are the obvious examples, but although my laptop negotiates 20V, it also charges (very slowly, overnight) from a basic 5V supply. I wouldn't risk passing in 12V that hasn't been requested via PD :-)

@derf oh i have a eurorack module that does this

@derf i don't understand electrical stuff well, my iphone charger says the basically the same thing, "output: 5V or 9V or 12V"
how do you know this one's a killer

@batterpunts Typically, USB-C PD devices negotiate the bus voltage – they get 5V by default and may request 9V, 12V, 15V, 20V (or other values in more recent versions of the standard). Crucially, some devices only support 5V and will fail and possibly burn when exposed to higher voltages.

Those devices will never request more than 5V, but if a power supply delivers 12V regardless, the magic smoke is sure not going to go back into device once it's done smoldering.

@arcaneoverflow @derf Yes, pretty clearly having a charger that simply provides 12V on USB is very bad idea. But also, if you are making an USB device, please make it 20V tolerant. Polyfuse or something. [And I believe at least some manufacturers are doing that.]

@whitequark @derf Yeah, I'm not stupid enough to do that. But if you are designing devices... please make them tolerate 20V on USB. It should not be that expensive. (Polyfuse?)

@pavel @derf I will for the next iteration of the thing I'm designing, exactly because of the prevalence of these horrible out-of-spec supplies; but I reverse-engineer a lot of consumer devices and I'm gonna tell you that basically only those which actually use higher voltages to charge seem to have any protection against Vbus overvoltage that I've seen. (I'm not perfect at RE and I usually only give limited attention to power circuitry but protection does stand out a bit)

@pavel @derf polyfuses don't work for this (by the time the fuse actuates, something important has already died) but there are cheap protection solutions out there. unfortunately you have maybe 50c for the IC and then 50c more because you need one more PnP feeder, and maybe a few cents here and there because of yield, overheads, etc and not a lot of vendors are likely to do this just for funsies

@pavel Yeah, they were probably designed for unregulated transformer supplies, from which you usually get few volts more when they don't have a significant load. These are somewhat rare nowadays and nearly everyone expects power supplies that normally deviate from the rating only in few 100s of mV and nearly none gives you even a volt above the rating, unless it's failing.

@derf Yet another reminder that CE is just a declaration by the manufacturer, not a certification.

That said, I severely doubt that this is compliant with CE, so maybe this could still open them up to charges?

@Fiona @derf CE also known as a china Exports?