Measuring USB cable resistance using USB testers 

I just had a look at the CT-3. That is a very nice tester. Having an electronic load makes calculation easier but it can be done using a resistor load as well, provided you use the proper math. I don't know how well the cable resistance measurement works in the CT-3 but given that it is a lot smarter than the one I used in the video, chances are good.

@@TheHWcave I received my external load from amazon and tested it with the internal cable resistance check and i am kind of disappointed, this was useless money in my mind. The reason is you get different results everytime you check the cable again and again. I am not an eletrician but you can see when you wiggle on the USB tester a bit you get slightly different voltage readings all the time, so i guess this is the problem here.

@@danbarb9728 How much resistance and how much change are we talking about? I have two good 1.5m USB-C to USB-C leads that each have a resistance of about 0.14 Ohm. Such low resistances are tricky to measure consistently because contact resistances are in the same order but if all is snugly connected the total resistance is that low. At 2A current that means I still lose 0.3V . If your measurement inconsistencies are in the order of

@@TheHWcave I adjusted the USB external load to 0.5A because the cable resistance function of the USB tester showed a symbol with 0.5. I dont think the male USB-A connecotr of the USB tester sits snuggly into any USB Power Adapter i have, there is always a bit of room for wiggling. If its connected with USB-C cable its sits more snuggly. But when i move the USB Tester with my had the voltage changes a bit as well but not much. I tried to test the cable with your method without the internal cable resistance function. The direct connection with a 0.5A Load had like 5.025V, the worst cable i had produced like a drop to 4.85V. By the way is there a way to test Power adapters with more than 5V? I think my cheap load i bought can only do 5V. But my PD USB-C Power Adapter can do 30W but with 20V, dont know how i can test it if that is really the case because i dont believe it since its a very cheap product.

You can change the font, colour, size and other things. Enable CC, pause the video, click on CC and then on settings next to CC. Maybe that helps?

Hi Michael, the cable should work fine but of course on a 30W charger will only deliver 30W. If your current cable is already handling this, the new cable will not make charging faster. Of course it depends also on the device (phone / power bank) and whether it implements fast charging in a compatible way to the charger. Confusingly: USB 3.0 =USB3.1 Gen 1 =USB3.2 Gen 1 (5Gbps) USB 3.1 =USB3.1 Gen 2 =USB3.2 Gen 2 (10 Gbps) USB 3.2 = USB3.2 Gen 2 x 2 (20Gbps) From a power delivery point of view, old style "USB 3.1" and above should deliver 100W where old style "USB 3.0" was limited to 7.5W. I have no experience with Thunderbolt but I think it is similar to "USB 3.1" in power delivery. The point is that the name USB 3.2 is about speed only and does not define the power delivery as it could be just an old-style USB 3.0 interface now branded as "USB3.2 Gen 1". Not too helpful, I know but from a power delivery point, USB branding is more confusing than ever.

@@TheHWcave wow this is very helpful. Thanks a bunch!

If you connect it between the charger and the phone, then yes. There is another video on my channel "USB tester surprises..." on 21-Dec which hopefully demystifies how the many sockets on a USB tester work.

Oh dear, what an open-ended question! It depends what you want to use it for, or rather with what devices and sockets plugs and cables, because all testers pretty much offer the same functionality. The difference is really in the convenience of use. With mainly normal USB plugs (type A..) and sockets, micro USB and some USB-C, the UM34C or UM25C are great. If you don't want Bluetooth, you can get the -non C versions (UM34 and UM25) with are cheaper. The UM25C probably has the advantage in flexibility over the UM34C because it has a wider current range (5A vs 4A) and has USB-C inputs and outputs while the UM34C only has USB-C inputs. The new TC66C is a dedicated tester for only USB-C (with adaptors you can use it with other USB connectors, but its more cumbersome). I am going to publish my review & teardown of the TC66C in the next week or two, so if a dedicated USB-C tester floats your boat, stay tuned.