Minibook X N100 - melted USB-C cable

Laptops Minibook X N100/N150/5100
1

SN: ZMinBXHY4H240201291

I have had a puzzling incident with my new Minibook X today.

First, to be clear, this topic has nothing to do with the infamous out-of-standard “USB-C” charger provided with the laptop (more details in Chuwi supplied USB-C charger will fry other devices - #16 by John_Hull ). It has not been plugged into the laptop, and is sitting in its packaging unopened.

I was charging the laptop with third-party peripherals. Admittedly, all cheap - sold under the SBS brand and bought at my local MediaMarkt. The charger is an SBS TETRGANLCD1C45K, and the cable was TECABLETCC31K. The charger is rated for PD up to 45W, the cable - up to 60w. Minibook X, in my experience (this is based on the readout from the charger and verified with a powerbank and different cable I trust) draws around 25W when charging and in use, so, well within the stated specs.

If it matters, the laptop is running Kubuntu 24.04 on kernel 6.14.0-28-generic (64-bit).

This setup worked well enough for a few days, but today, after using the laptop when charging for a few hours, I noticed a notification that the laptop was no longer charging. When I disconnected the cable, I noticed smoke. On closer inspection, the metal connector on the cable had started to melt through its plastic housing on one of the sides. This may well have been my mistake, but I had the cable plugged into the rear port - one normally used for the provided charger. I have already gotten rid of the cable.

I am now trying to understand what exactly was the fault here:

  • user error (plugging into the rear port)
    • maybe? I am not able to find detailed information on what that port does or does not support. It was happy to draw the same 25W as the front port, and supported data transfer when used with a flash drive.
  • the charger
    • seems unlikely? The end of the cable plugged into it was fine. The wattage it reports also checks out vs. my powerbank.
  • the cable
    • I really want it to be true, as replacing a cable is easy. To be fair, it was a cheap cable, it did not advertise being USB-IF certified, and it is not unheard of for noname manufacturers to lie about their PD ratings.
  • or the laptop (faulty USB-C ports)
    • I really want this to not be true, as I imagine the process of exchanging/warranty claim would be difficult, and so would be replacing the USB-C ports on the motherboard.
    • I have tested charging it, in both ports - rear and front - with other USB-C cables, including an HP 65W rated USB-C laptop charger (USB-IF certified for up to that wattage) and a cable supplied with an iPad Pro (unsure of the wattage rating). None of them smoked, but I did not use them as long as I used the SBS one. All of them got fairly warm after some period of charging with use (so, ~25W draw) - regardless of the port used.
    • For what it’s worth, I tested the rear port after the incident both with charging and a flash drive - it works for charging and data still.

So, is there a good way to know what exactly happened here and, most importantly, am I operating a laptop that is a potential fire hazard? I do not know enough about electrics myself to say. Should I expect something shorted out, or is it normal for cables to get warm during charging, and SBS just used cheap easily melting plastic?

2

It is possible that several factors have coincided here: a bad charger and a bad cable. There are 2 parameters to consider here: power in watts and current in amperes. It is possible that the charger did not output 20 volts (like the PD chargers for this laptop), but much less. Because of this, the number of amperes has increased. The cable was not ready for such tests (especially its connectors, where there is a bad solder), so it began to overheat and melt. There is nothing special here in terms of electrics.

3

This looks like an issue more to do with the cable used. I would have been more concerned if it happened while using the Charger/Cable that came with the unit.

4

21 August 2025

I received this email yesterday, inviting me to respond simply by replying to the email. Therefore I suppose this will be a public reply. Since the original post was August 1st, I’m supposing the poster sent me this explicitly and I am not receiving it simply because it links to my remarks on the Chuwi stock charger abomination which, apparently, they still ship with the current model minibook.

The fact that your rear port still functions means whatever damage there may be is minor. Despite the power levels, usb-c PD uses quite delicate connectors, so if there had been serious damage, you would know about it due to loss of functionality. What damage may there be? Burned contacts in the connector or possibly blown protective circuits in the Minibook. Since everything works, at worst the contacts are now offering a slightly higher impedance and so the lifecycle of the connector has been slightly shortened.

I looked at the product links you provided. I would never buy those products because there is no technical data provided. A reputable supplier will explicitly state the level of PD compliance by listing the voltages and currents that the charging device is capable of supplying. No such data is provided. I bought a 65w Chinese charger (Qeneq) at about the same price from Amazon. They specified the PD compliance in their listing.

That said, a 45w charger is operating in the lower power regime of usb-c and so will be limited to 3A. I have never seen such a charger that could not supply all of the mandatory voltages up to the maximum in the low power regime of 20v. The Minibook demands a 20v power delivery supply. It will NOT accept a PD negotiation of anything less, so the fact that you were charging with the adapter indicates it was capable of negotiating and supplying 20v. The rear Chuwi port has some kludge built in that recognizes when a non-negotiated 12v is immediately supplied and feeds that to some circuit not compliant with usb-c to condition the voltage properly for the internal battery charging which is nominally 7.5v (two lithium cells). 25w at 20v means your charging current was 1.25A, which is only about half again the current that any usb-c port must be able to handle, so I doubt you burned any contacts, not even slightly.

The most likely failure is in the cable solder joints for the power or ground wires on the Minibook end of the cable. Cable flexure, or perhaps an imperfect joint at time of manufacture can increase the impedance of the joint. That means any current flowing through the joint will dissipate power, heating the surrounding material. When the temperature gets above 100C, most plastics will begin to melt. The principle exceptions are teflon and silicone, and you have to pay a lot more for those materials, but the melting plastic is not the problem. The problem is the joint. A good joint should not exceed 0.1 Ohms, which will dissipate an eighth of a watt at your current level. If the joint degraded to 1 Ohm, still a tiny impedance by most standards, it would dissipate 1.25w, enough to significantly heat the joint, leading to further degradation and increase in impedance leading to more heating and a cascade failure resulting in an open connection. That was when you machine reported that you had lost power and were operating only on your battery.

As a side note, the only reason I am replying is that you use Linux. That indicates you are capable of learning about these things and I am not wasting my time. If you were a windows user, I would have disregarded the email.

John Hull

1 Like
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This was almost certainly the cheap cable failing under load due to poor quality. Heat concentrated at the connector because of resistance, melting the plastic. Cables getting warm is normal (due to inherent resistance in wires/connectors), but smoking/melting indicates a defect—SBS likely used subpar materials that couldn’t dissipate heat effectively.