Chuwi supplied USB-C charger will fry other devices

12 December 2024

So I had a slightly more disturbing experience with the Chuwi Minibook X stock charger. I bought mine in April 2022 directly from Chuwi (n5100, 2560x1600 display) and have been running linux on it since May 2022 (I won’t use windows). Things were fine until 18 November 2024 when I plugged the Chuwi 12V charger into the dedicated port (rear) as usual and was rewarded with magic smoke.

Now I am an electrical engineer, so I carefully proceeded to diagnose the problem. I just got back up and operating on the Minibook X two days ago, and I am composing this on the Minibook X.

The charger normally has a dim blue light that glows steadily. After the magic smoke it presents as slowly blinking blue. There is, as far as I know, no documentation on what that means, but I presume it means the charger is a brick now. Trying to find information on the blue light is how I found this discussion thread.

To resolve the issue I bought a 65w PD capable charger and a Fnirsi FNB-58 usb-c power tester. I also spent about a week coming up to speed on the usb-c specification, which was not part of my inventory of knowledge. The following comments reflect that new knowledge. No one can be expected to be an expert on everything, and previously I had simply assumed that the manufacturing engineers designing with usb-c were competent and adhered to the specifications, without personally knowing what those specifications were. I generally trust engineers. As it has turned out, my assumptions were in error and my trust misplaced.

Before I begin with the substance, I would like to point out that this forum website sends my processor temperatures up to 70 degrees C. Since my older Minibook X uses passive cooling, I monitor temperatures closely. Normal use has temperatures between 45 degrees C and 60 degrees C, with the higher temperatures seen when watching video content. When the temperature breaks 70 degrees C, I disconnect and shut down as a protective precaution. I have noticed certain websites abuse their visitors by running cypto-currency miners or other noxious javascript in the browser, that is to say, locally on the visitor’s machine. That is the cause of the temperature peak. Apparently Chuwi shares that disregard of its customers’ well being.

There also does not appear to be any way to log off the forum, apart from closing the tab. Perhaps it is also necessary to disconnect to disable the login cookie - I haven’t tried that yet.

Therefore I am composing this off line, and will copy-paste to post and then immediately shut down to thwart the javascript abuse.

The information is organized in numbered sections:

  1. The Chuwi Power adapter is NOT usb-c compliant
    =================================================

I guess this is obvious once you are familiar with the usb-c specification. In fairness, Chuwi does not make any claim that the adapter is compliant. Indeed they obliquely admit it is not with the disclaimer in the user ‘manual’ (it is not a manual, but a minimally necessary summary):

“Please make sure to use the original power brick for charging. For problems or faults caused by any third-party adapter, the company does not undertake responsibility.”

A normal person will read this and interpret it as a typical marketer’s lame attempt to scare his customers into staying within the walled garden. Apple is famous for such nonsense. The reality is, this is an extraordinarily indirect way of proclaiming the charger is NOT usb-c compliant. An honest disclaimer would be something like this:

“The power brick supplied by Chuwi is NOT usb-c compliant. It can only be used safely using the rear usb-c port on the Chuwi device it was shipped with. It ALWAYS supplies 12v at up to 2A which violates the usb-c specification by failing to supply only 5v at up to 800mA until a higher voltage and current is negotiated. The adapter is in fact simply a barrel jack adapter fitted with a usb-c male connector. It has only the power and ground wires in the cable and no others. USING THE CHUWI ADAPTER WITH OTHER DEVICES MAY DAMAGE OR DESTROY THE OTHER DEVICE AND POSSIBLY ALSO THE ADAPTER. CHUWI WILL NOT BE RESPONSIBLE FOR MISUSE.”

It is notable that there are no brand markings on the adapter that would in any way connect Chuwi with its manufacture. In my opinion, the text in CAPS should be printed in a large yellow font directly on the adapter, assuming Chuwi is willing to risk the reputation destroying consequences of distributing it. Most of these adapters will eventually find their way into thrift stores and second hand shops, happily destroying equipment long after the original laptop has been recycled.

  1. There is in fact a usb certifying body
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There is however, no enforcement, nor could there be realistically, apart from lawsuits, which would greatly discourage adoption of the standards. In theory, the USB Implementers Forum, Inc., which created the various usb standards, requires certification in order to use the emblems and markings associated with usb cables and devices. Certification is provided by a large number of third party organizations. Certification costs money.

In practice, many manufacturers simply use the logos and markings because they can. Other manufacturers err on the side of caution by omitting the various markings. The Chuwi power brick is one of those devices. Mine is manufactured by Shenzen Ruijing Industrial Co. LTD. The Minibook X in contrast has one of the usb emblems screen printed over the rear port. Ironically, it is the forward port that is actually compliant, and it has no markings.

Arguably, the usb-c connector itself could be a trademarked emblem. It is, however, apparently not, which brings us to the next point.

  1. The usb-c mechanical connector specification was created explicitly for usb-c
    ================================================================================

What this means, is that when ordinary people see a usb-c connector, male or female, they assume the device it is attached to is compliant with the specification. In a perfect world, this would be the case. Unfortunately, Chuwi is not the only company willing to risk its reputation by supplying abominations like the stock Minibook X power brick.

Once you are familiar with the specification, it becomes clear that any power brick that has a built in cable with a usb-c male connector on the end (that is, that does NOT use a female connector to supply power to a male to male usb-c cable) is NOT compliant, and is in fact a barrel jack power brick masquerading as a usb-c adapter. ALL such devices are abominations.

If you want an idea of how bad some ‘usb-c’ things can get read this:

Of course that was eight years ago, and things should be better now. They will get even better once manufacturers like Chuwi fully understand that using power bricks like the stock Minibook X one is a complete abomination, and decide to conform to the specification.

  1. Power delivery and data delivery over usb-c are disjoint specifications
    ==========================================================================

What this means is that you may build a device or cable that uses the usb-c connectors to deliver only power, to receive only power, to transfer only data, or any combination of these. Specifically, power delivery does NOT depend on data capabilities to negotiate voltage and amperage. It uses a special wire in the usb-c cable for that purpose and that wire is not required to be present in all use cases.

The Minibook X forward port is a full function port. It can deliver power, receive power, and communicate data, and, to the best of my understanding, is fully usb-c compliant. In future revisions of the Minibook X, Chuwi would be well advised to ditch the rear port and replace it with a fully compliant port identical to the forward port.

One of the early critics in this thread correctly pointed out that there is no requirement to conform to all aspects of the specification. That, however, can not be misinterpreted, as he does, to imply that violations of the specification are permissible. Specifically, omitting 5v 800mA default power delivery (the only delivery permissible with a cable that omits the negotiation wire) is a violation of the specification. Nowhere does the specification permit 12v only power delivery, and, in fact, 12v is not even part of the downward compatible voltage list in the specification. Those voltages are 20v, 15v, 9v, and 5v, at up to 3A, and now with extended power delivery 48v, 36v, and 28v, at up to 5A are included in the list. Many chargers supply the completely optional 12v supply only because it is historically common and very useful. It may turn out that something similar will happen with the conspicuously absent 24v and 32v in the extended specification.

Again, the fact that Chuwi uses only this optional voltage does not in any way make it compliant. The Chuwi charger is NOT a usb-c charger - it only pretends to be by using the usb-c male connector.

To underscore the point, have a look at:

Now violating specifications for one off projects is just a normal day for a hacker, but if you look at the 67 comments under that post, most of them concern the possibility of accidentally destroying equipment. Many suggest there are better less dangerous solutions to the proposed hacks. When even knowledgeable hackers look askance at the practice of abusing the usb-c specification in a one off, Chuwi engineers should sit up, take notice, and change their ways.

Concluding Remarks

I very much like the Minibook X, even with the flaky keyboard under linux (I made a work around), and the thermal issues of the original version. I rarely have to shut down to cool off, and then it is only because of an abusive web page.

If the new n100 version had a 2560x1600 display that maximally utilizes the frame to frame real estate of the small form factor, I would not hesitate to buy one, even with the crappy non-compliant power brick. The Minibook X is, for me, the perfect daily driver, but only because of the efficient use of display real estate. The new one is a non-starter. So much space is wasted in bezels, and I won’t go back to a primitive 1920x1200 resolution now that I’ve tasted luxury.

It boggles my mind that so many crab about the loss of a few hundred pixel square in a corner of the display I never use anyway, and are willing to trade that for the loss of tens of thousands of pixels in a wide bezel. I never use the camera anyway. In my mind, Chuwi was brilliant in leveraging an existing supply chain by using the Huawei Mate Pad display in the Minibook X. Your marketing should highlight that brilliance, not invented rubbish like “the world’s first hole punch display”. People aren’t stupid. I keep the icon for my soft keyboard (Onboard) under the camera. The edges stick out, and you can click on it by clicking when the pointer disappears under the camera.

So what caused the magic smoke? I think fatigue in the internal insulation of the power brick cable caused a break in the insulation that eventually became a short. I won’t be sure until I dissect the power brick, and that is not a high priority just now. One thing is certain: the brick cable is the traditional bad design of a barrel jack adapter. It has the positive wire in the center with a sheath of ground wires around it, and then the external jacket. That design is notorious for failing due to fatigue. I’m just glad to be back up and running, now with thorough knowledge of the usb-c specification and fully compliant equipment.