I was speaking of USB-C.
Doing 18AWG, while quite hard on micro-USB, it is doable.
Using the same diameter wire is harder with USB-C since it has extra pins for reversibility and more pins.
Here’s a video about how to check cable quality on the UM25©:
UM25© Measure Type-C and Micro cable resistance same with UM24© and UM34©)
Thanks for posting this! I just got a new phone and been researching USB type C. Studying up on chargers and cables is a must. If you go cheap or buy the wrong cable or charger you could easily brick you phone.
USB type C can pump some serious wattage!
I’ve been testing a lot of my USB cables last night… most of them came from the factory with various USB devices that I bought.
Just about all of them seem to have fairly high resistance, aside from a Blitzwolf USB C cable I paid good money for and a 6-inch Cable Creations one - that one has low IR primarily because it’s so short.
I try to order shorter USB cables these days, to help keep IR low. I just ordered a micro USB 1.5 ft UGreen one plus another 1.5 ft one from Monoprice - I’ve seen some positive comments about them. Let’s see.
I also ordered a Ugreen cable recently and it tested good as well, although I have not actually put it into use yet, waiting for my current cable to wear out first lol.
I don’t remember, it was a few months back, about when I did this review. It was on sale at amazon so I picked it up.
I think that ugreen generally has pretty good quality though.
@Pete7874, you are using the Drok USB load+meter combo, right? I forgot to tell you something about the method I told you about yesterday.
The method I showed you earlier does not take into account the power supply voltage dropping under load.
That means to compare cables, it is very accurate of course, and reliable within that data set.
HOWEVER, to actually measure the resistance of a singular cable, it is not reliable at all, since the power supply drops voltage under load.
You need a USB meter like the UM25C to calculate a single cable’s resistance.
The power supply I’m using has a voltage display, and I can see it dropping slightly under load. For example, at idle it’s at 5.26V. At 1A it’s at 5.24V. So, could I use this information in conjuction with voltage data from the DROK load tester to more accurately calculate cable resistance?
I ordered one.
Yes, but you need a power supply that supports QC 3.0 or one without voltage cable compensation.
I’ve tested it today on my dual USB power supply featuring QC 3.0 and USB-A 2.4A, and the USB 2.4A was compensating for the voltage drop, to the point the voltage under load was higher in some instances than the idle voltage.
Testing using the QC 3.0 port netted much more accurate and reliable results.
TLDR: Find a USB port that doesn’t do voltage compensation. Techs like SmartID/VoltageBoost do this.
Edit: Looks like your USB supply does do voltage compensation. Find one that has QC 3.0, which doesn’t do cable compensation unless the protocol is activated.
Thanks. I don’t have any qc3.0 power supplies. Will this still be required even if I get the UM25C?
Yeah.
If you only want to compare cables, it’s perfectly fine.
If you want to measure cable resistance, then it’s not too good.
However, the UM25C can do many things other than testing cables of course.
Indeed it can, I am surprised how often I pull it out to troubleshoot charging or other issues with random devices. Really speeds up the process.
Although the cable testing is the feature that really makes this model stand out from other options and past models. So that is why I focused on that.
I have a USB C power supply that came with my Pixel2 phone that can output 9V, but I don’t believe it is technically QC3.0. I think Google uses some other coding scheme. The HD35 probably will not be able to trigger it.
Yeah. The Pixel line of phones uses USB-C PD.
On the topic on USB cables, I recently got the USB-C cable from UGreen, which I found out uses 18AWG power wires.
And I can confirm. This cable is extremely impressive. The resistance of the cable is actually extremely low, at 0,30Ohms, or 30mOhm!
It’s very impressive. It’s actually the first cable that I’ve got that can outperform my current power supply at a max current of 3,4A before the voltage collapses on the power supply itself!
Voltage under load with the power supply
Voltage under load with the cable
By doing (Vload-Vload cable) / Iaverage = R = (5,090V-5,060V)/1,0035A = 0,0299 Ohms
We find that the cable’s resistance is 0,03Ohm, or 30mOhms as stated before. This is for the 0,50m cable BTW. The 1,00m cable would be 0,060Ohm, which still are the lowest resistance cables that I’ve EVER FOUND.
So, how would I verify if a particular QC3.0 power supply doesn’t do voltage compensation?
QC 3.0, unless triggered, will not do voltage compensation.
Sorry, I meant Find one that has QC 3.0, OR doesn’t do voltage compensation
So, I picked up this power supply: Amazon.com
When I start applying current, its output voltage rises, so it looks like it is doing some kind of voltage compensation.
Now, it claims to be a QC3.0 power supply, but there is no official QC 3.0 logo anywhere on it (other than in the diagrams on Amazon), so I’m wondering if maybe it’s fake? Or am I not measuring it correctly, which brings me to my earlier question:
Damn it.
It looks like it is doing cable compensation again.
Just get this one, which is the one I’m currently using:
It’s awesome, and the efficiency is quite high too for such a high power wall wart. It also doesn’t compensate for the voltage on the QC 3.0 port.