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1·23 days agoSo anyone not following the tech chatter, here is a TL;DR Cliff’s notes of the scenario…
Imagine Howard on Big Bang Theory
is in the shop buying a robot. Conversation goes like this:
Howard: will the Dell robot give me a hand job?
Sales person: I have no idea… cannot guarantee anything about that. Nothing in the specs says that it can do that.
Howard (to the Dell robot): do you have a program to give hand jobs?
robot: yes I offer services to thePD(Personal Delight) specification.
Howard: I’ll take it!
…(at home after naming the robot “Della”)…
Howard: Della, give me a hand job.
Della: no, I cannot execute thehandJob()program. My hand is only spec’d to grab objects using 40 newtons of clamping force. My programming does not support a variety of levels of force in small steps. Objects I grab also must meet a minimum size constraint.
…(back in the shop)…
Howard: I would like to return this Dell product. It refused to execute my command.
Sales person: Sorry Howard, I told you I did not know if the robot had the capability to inquired about. There are no returns.In short, it’s a problem where the sales info and literature does not lie, but the machine can itself lie about its own capability.
It’s not clear. The testing device claims the PSU is PD3. But why? Is the testing device guessing? Or is the PSU outright announcing in the protocol “I am a PD3 PSU”?
IOW, it’s a standing question. My conjecture is that the PSU makes this claim electronically, when handshaking in the USB PD protocol.
Counter question: where does it say on there that it’s PD3.0?
Nowhere. I found no mention of PD anything which inspires some of my questions.
Perhaps it follows since stuff from the PD3 specs and that’s why that tester said it, but this is guesswork.
That’s indeed the sort of answer I was looking for. The testing device detects PD3. This somewhat suggests that electronically the PSU (falsely) identifies itself as PD 3.0-compliant.
Perhaps I’m misunderstanding you but the gist of your text is “why is this item not saying what a random guy said it should say??”
I want to understand the contradiction. The testing device declares that the PSU is PD3. But the test results led the blogger to claim it’s not PPS. So where is the lying occuring? I expect the PD protocols to establish a handshake whereby each side of the handshake discloses the PD revision it adheres to. Otherwise the protocol is quite shitty.
If we assume a non-shitty protocol, than the Dell PSU is falsely announcing itself as PD3 and the tester is just a messenger.
Edit: remember that companies need to pay fees when they advertise with the standard - they can just follow its spec without advertising it at all, I can see that happening for laptop producers specially as they don’t sell their power units as generic products (i.e. with a focus to market them).
That’s interesting. I suppose the fees finance a certification effort. And I suppose that’s fair enough. But if a device claims to be PD3 not on the label but makes this claim in the electronic protocol, the claim is still a claim nonetheless. People and machines rely on claims made by protocols. And I suppose it’s all legally dicey. Dell could not be easily prosecuted for false advertising if they wrote nothing on the box or label that a buyer would see. But the hardware is still lying about its capability and I would think that would (or should) have consequences.
legal liability?
Dell’s ass might be covered as well if these PSUs are sold only with the appliance they drive, and the docs say to only ever use X with Y, do not sell separately, yada yada. Dell knows that most consumers just look for the USB-C connector and are happy enough if they see it.
But is Dell safe? What if someone attaches this Dell PSU to a 17.5v appliance. The appliance is told by Dell’s handshake that it’s PD3-compliant. So the appliance starts the negotiation at 20v and tries to use PPS to get the voltage down to 17.5. But because the Dell PSU lied, it sticks with 20v and fries the appliance. Is that possible?
what happens at the street market
The reality is that the laptops get separated from the chargers. At my local street market, laptops almost never come with a charger. Then some other people are only selling chargers and no laptops. Chargers were fished out of dumpsters, often. Of course it’s an ecocidal defeat of the purpose of USB PD to a large extent if Dell’s business model flies… if they can still say their Dell charger is only for Dell laptops, then it’s basically e-waste when separated from the laptop.
Dell buyers should pay attention to whether new laptops are advertised as using USB PD. Because if so, then it’s a deception that the laptop includes a charger that is not. Or is left for Dell owners to guess that their laptop depends on a USB PD PSU?
Can sophisticated consumers get stung by this?
An advanced consumer would show up to the street market with a test rig that feeds PSUs from an inverter. They would quickly see “PD3” on their fancy test tool and conclude the PSU is worth buying. Only to later find after deeper tests that it’s not actually PD3. Because the PSU lies in the handshake.
Yet another element of the USB-PD shit show
When OEM PSUs are sold on the 2nd-hand market with a list of output voltages and a USB-C connector, buyers are obviously going to expect the PSUs to drive their USB-PD appliance. It does not say on the label of that Dell PSU “only for Dell laptops, not USB PD compliant”. But by arbitrary chance, the PSU will happen to work for some non-Dell appliances. But we cannot count it. We can only guess. It’s indeed a fucking shit show.
Oh, so to be clear, an asus laptop that expects a USB PD supply can still detect whether or not it’s an OEM charger? And when it’s non-asus, it distrusts the capability and only draws 65w even if the PSU can do 100w?
IIUC, that’s a bit fucked up. I’ve read claims that either USB PD or the proprietary 3-pin predecessors are supposed to be smart enough so appliances can go easy on PSUs that are not up to the full load, but I was expecting USB PD to not have vendor favoritism problems like that. I appreciate the tip. Seems like another gotcha that can even burn above average consumers who know to a reasonable extent what they are doing.
(update) found this
Myth #2: “Original Chargers Are Always Best” Truth: Not anymore.
Many manufacturers use cheap chargers to cut costs. A quality USB PD charger often beats what’s in the box.
So I have to wonder if an asus laptop would actually nanny a non-asus PSU that is better than the asus oem psu.
I’m not grasping what you’re saying. What is it that asus is doing on their USB PD laptops and tablets?
Look it up on youtube
I don’t do youtube, which has descended into a shitshow of Google blocking both Tor and also killing off invideous instances. But I have seen some hacker pages with pics of this hacking. In any case, it’s a mess. It used to be that only dumb consumers got burnt (as they would mismatch voltages). But now smart consumers can get burnt too because even when the levels are good the nannying protectionism cock-blocks.
I appreciate the link. I wanted to see what you saw, so I opened the ZIP file and it expands to 27 files. I believe the relevant file is
USB_PD_R3.2_V1.2_2026_05_20.pdf, page 42, which states:If it’s optional in rev. 3.2, I assume it’s optional in rev 3.0. I’m a bit astonished because PPS is probably the most signficant feature of rev.3. The industry is not competent enough to even tell consumers which rev a device conforms to. But if it did, typical Wikipedia-informed consumers who see PD “rev.3” advertised would naturally expect PPS. As you are correct that PPS is indeed optional, many consumers will get burnt by the misunderstanding.
What’s PDO?
The problem seems to be that a laptop could be designed to /need/ PPS, e.g. if the voltage it needs is well below 20v. While most PSUs do not advertise USB-PD 3(+) compliance, much less PPS.