USB cable quality / resistance measurement?

OK…… thanks ZoomieFan.

[quote=ZoomieFan]

Thanks, I got these numbers from a little round of googling, so I'm stickin' to them :)

If you want the best of the best micro-USB cable, here it is:

If you want the best of the best USB-C cables, here it is:
https://www.aliexpress.com/item/Ugreen-5A-USB-Type-C-Cable-for-Huawei-P20-P20-Pro-USB-3-1-Fast-Charging/32844394210.html?spm=2114.search0104.3.56.60c334b5DUL8VD&ws_ab_test=searchweb0_0,searchweb201602_1_10152_10151_10065_10344_10130_10068_10547_10342_10325_10546_10343_10340_10548_10341_10696_10084_10083_10618_10139_10307_10059_100031_10103_10624_10623_10622_10621_10620,searchweb201603_13,ppcSwitch_2&algo_expid=f1e8772f-d626-46a0-8834-30774854cf75-6&algo_pvid=f1e8772f-d626-46a0-8834-30774854cf75&transAbTest=ae803_1&priceBeautifyAB=0

Both are 18AWG USB cables. So, top of the top quality :+1: :beer:

Thanks BSM… good info. :+1:

Simply having large gauge doesn’t make a cable good.

The flexibility and durability of the insulation, the quality of shielding, the reinforcing cables inside, the joining between cable and connector, and many other things also matter.

Having had a Dash Charge cable which uses 18AWG wires, and is a great quality cable, and the fact that UGreen cables are great in general, I would have no problem that it is a high quality cable.

Ugreen is definitely one of the better brands, but I’m just saying that in general it is a bad idea to only consider wire gauge.

+1

You are right.

As you said, there are many factors in making a good USB cable.

The other problem with using thicker wire gauge is that flexibility is also affected. And the cable is made even heavier and thicker.

measure the cable resistance, you can use out UM series (um24, um25, um34) to measure the cable resistance
this video show how to measure

Thanks! The more advanced meters now do this automatically. You plug them in directly to the supply, then with the cable in between just like you say, and it calculates the difference. Only thing is most meters only have male USB A in or micro USB, so you can only test micro USB cables. Unless you have this:

Converts micro USB, USB C, Apple Lightning and even direct + and - into female USB which you can then plug your meter into.

I had already bought the Qoopow Qualmeter before I found that though. Yes it’s overpriced, and doesn’t give you direct results.

I bought that interface converter board too, but haven’t used much. It’s handy for converting various interfaces. But for measuring resistances, then I won’t exactly recommend as the board will also add some amount of resistance (so it will affect cable resistance measurements by adding some amount of resistance).

Hmm I wonder if you can calibrate it with a known cable. At least you can use it to compare cables even if you can’t get an absolute value.

It is possible to directly connect the converter board to any given meter by soldering the power leads with short thick wires, plus the data leads. Frankensteining but useful job, of course.

Cheers ^:)

But there are 2 currents - with and without the cable. Which current should I use?


I don't see how you'd get 2 different currents?
You set the load to a specific current and leave it there. You don't have 2 different currents.

It could be because I’m using a battery as a load and it’s unstable, but shouldn’t the current drop if you add resistance in series with a fixed voltage source?

I don't now man, I just mess around with meters and make videos.
Maybe someone else here knows what you're on about...

If need meter only resistent, then cheapest way, I think, are use corresponding female USB sockets

I mean if you look at HKJ’s reviews like Review of USB battery box Chuwi Q-Power USB-C power bank 10000mAh M10 a lot of them mention
“What happens if the charger drops in voltage or a long cable is used? My usual 0.5ohm resistor shows it clearly: The charger will reduce charge current to a much lower value. ”

Didn't come across that behaviour in my tests, to be honest, and I've tested quite a few cables, chargers and powerbanks.

I don't know why, maybe my testing setup doesn't trigger the protection.