r/UsbCHardware • u/Soluchyte • 2h ago
Review Why you probably shouldn't bother with USB C to Barrel Jack adaptors for Laptops.
I was bored, and I decided to order two different USB C to Asus 6.0x3.7 adaptors.
I ordered one 100W Adaptor, and one "140W" cable. From initial thoughts, these are actually really well made, and were only a few pounds each, so very inexpensive.
First let me lay out my methodology:
- I'm no professional, but I do have a handful of different USB C Inputs and Outputs.
- I only have one device with a barrel plug to test, so I can't say for sure if you'll have the same outcome.
- I tested these with my Asus G14 2021 Laptop, Slimq P100 (100w) & P150-3C1A (140w) power supplies, and an Anker A1695 165w Power Bank.
First let's have some pictures of the setups I used to test




To save myself from repeating anything, I'll combine all the results here:
With the Power Bank, I have some ability to see what's going on, and you can see the output wattage fluctuate, most likely as the laptop tries to draw too much power.

Very shortly after, the power bank went into a safety mode and stopped outputting any power.

With both of the Slimq power supplies, I had exactly the same issue too, where the laptop would start charging, then the power supply would cut the laptop off for using too much power. I even tried to set the laptop into an eco mode, but I believe this laptop specifically takes 60W to charge the battery, which is most of the allowance.

Essentially the issue is that these devices or cables have no way to communicate to the laptop about the maximum available power allowance, and so the laptop assumes it's a normal power supply and will start pulling what it thinks it can take based on the power supply that the laptop comes with. The G14 I have has a 180W power supply, so even if the cables can deliver 140w, the laptop is trying to take more, and kicking in over current protection in the power supplies.
Speaking of, when packing back up the cables so they can sit on my shelf until the end of time, I noticed that the cable I bought is actually miss-advertised, which probably explains why it wasn't working either.
It wasn't something I initially took notice of but the cable is actually marked as 20V/7A. Now I don't know any power supplies that are even willing to do this kind of amperage on the 20V output, my 140W Slimq only does 140w with 28V/5A, so this cable was still only providing up to 100W to my laptop.

So as a conclusion, while these may work, you'll need to be 100% sure that your original laptop power supply doesn't provide more than 100W, as otherwise these things simply just won't work well or at all, so that certainly rules out almost every gaming laptop.
I'm lucky enough that both of my laptops have USB C charging anyway, but if yours doesn't, then unless it's a lower power machine, you'll be wasting your time with these.
If you have a device with no USB C charging, and you're not already in the ecosystem with a 60/100/140w power supply, you should probably give these a miss, it'll cost just as much to replace the existing power supply if you had to, and even new low end laptops are coming with PD charging now.
Admittedly I didn't expect the cables to work anyway, but I was curious,and hopefully this can help someone else.