Measuring USB cable resistance using USB testers
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- Опубліковано 25 лип 2024
- The quality of a lot of USB cables is rather poor when it comes to charging. Using a bad cable you can easily wait 20% longer for your phone to charge. The problem is that there is no obvious way to recognise a bad cable from a good one. They all look the same.
In this video I show how you can easily determine the internal resistance of a USB cable using only a USB power source, like a charger or power bank, a USB tester and LED light as load. I demonstrate the method using the Ruideng UM34C and the UNI-T UT658 USB tester.
I reviewed both of these earlier and you can find my reviews here:
UM34C review: • Review and tear-down o...
UNI-T UT658 review: • Review and test of the...
The power bank used in the video is a ASDA Blackweb 2600 mAh and you can find my review and tear-down of it here: • Review and tear down o... - Наука та технологія
What's wrong with us tech nerds to make it through this entire video without falling asleep, lol?
Well done mate, keep it up!
The video I was looking for, explained with the detail and pace I needed. Thanks a lot!
Thanks for the video! I enjoyed learning these tips and found a few bad cables in my inventory.
Very interesting and useful!
I was going to buy a UM34C but thanks to your video you just saved me £30!
Thanks. Just bought the ruideng tester. Gonna check all my cables like u did.
Nice, useful and well explained video. Thanks.
Very well done and laid out.
More evidence that we just never know what we are getting with any ready made cable these days - conductors too thin, or made of dodgy material, or badly soldered/crimped all seem to show up regularly. 20 years ago, I don't remember these faults being very common at all.
Recently I bought some USB cables on aliexpress (USB A to 5 pin, for mouses, keyboards etc.) and I laughed so hard when you told 1 Ohm being bad. Mine are ~3-4 Ohms with the sad record of 19 Ohms on ground of one of the cables! And yeah, I was looking for better ones, not the cheapest...
Anyway: great video, cheers! :)
Great video, really helpful thank you.
best usb analysis video on the internet.
Just the video i was looking for
really useful video!
Very informative, thank you.
Super super useful. Tqvm
Thank you - very nice.
Thanks for sharing =)
nice and very informative video one thing is that your drawing is hard to figure out because of the translation in the bottom. thanks more power to your vlog
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?
Just bought one of these. When it shows amps, is that that the charging amps going into phone.
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.
Instead of the LED light you can buy an electronic Load from ebay as well? I have the AVHzY CT-3 USb tester with the load modul, do you think the internal cable resistance function is flawed on this device as well?
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.
Hi, may i ask you something about cables and chargers?
I am planning to buy a usb-c to c 3.1 (gen 2) 100W/5A and I will use it for my PD 3.0 30W wall charger. Purpose is for fast charging smartphones and powerbanks.
Will that usb-c cable with higher watt/ampere affect the lower charger watt? Will that affect its charging speed?
My other question is, what is the difference between USB 3.0, USB 3.1, 3.1 GEN 2, THUNDERBIRD regarding charging speed. I know that their transfer speed difference already. But how about regarding charging speed to smartphone devices?
Thank you in advance and more power.
More good and informative videos.
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!
Which usb tester would you recommend?
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.
Thanks for this video explaining things. I found that using an iPad Pro (30% charged) and an iPhone charger produces a consistent ~ 954 mA load regardless of the quality of the cable you test. Not everyone has those items... but if you do :).
you could also get a usb varable load and this will have the same principle
Just give me the cash. I'll open my own business.
I have to post thumb down because you measure with fingers and thumbs.