[Matthias] bought cheap clip leads online and, wisely, decided to check them. We’ve had the same experience that he’s had. Sometimes, these cheap leads are crimped and don’t make good contact. However, you can usually solder them and completely fix them. Not this time, however, as you can see in the video below.
The resistance for the leads was a bit on the high side, which is usually a sure sign of this problem. But soldering didn’t really make a big difference. A homemade clip lead, for example, read under 20 milliohms, but a test lead from the new batch read about 260 milliohms even after being soldered.
A thermal camera indicated the problem was actually the wire. At first, he thought the wire was just very thin. While it was thin, that wasn’t the real problem. The wire looked normal enough, but sanding the wire showed that it might be only copper-coated. Turns out, a magnet would grip the clip leads meaning they were iron wires coated with copper.
We were amazed at how many leads he was able to find with iron in them, primarily those with clips on at least one end. Oddly, mouse cables were also magnetic.
So, the lesson is to test the resistance and pass a magnet over those wires. Depending on your application, a few hundred milliohms might not matter. But you should at least know that some of your clip leads may have an order-of-magnitude difference in conductivity.
If you need an easy milliohmeter, there are plenty of options. You can even just haywire something up on a breadboard, or — like in the video — use a 1A current and measure millivolts.
I ended up junking the “fake” wire, and reusing the clips with pieces of regular hookup wire. If the clips were bad, replaced them with some good quality Japanese small alligator clips I found cheaply on line..The lack of aggro dealing with flaky leads is worth the effort!
Buying stuff from China really is like a lottery. Most often you get junk, but every once in a while you win and get good stuff cheaply. Keeps you buying their crap…
In this case I don’t think there’s ANY good clip leads out there.
I’d be willing to pay a bit more for some but they simply don’t seem to exist.
I think the sets sold by Adafruit and Sparkfun have actual copper wiring. They are available also on Digikey etc.
I bought some really good leads from an eBay seller years ago… Copper clips and proper copper wire with silicone insulation… Both light and heaver duty leads. The difference here was he advertised them as high quality clip leads, and had all the details and photos to back it up. Other clip leads haven’t been worth what I paid for them, really, as they have cause more problems than been any use.
Pomona. But. $7.50ea. But they are wonderful. https://www.digikey.com/en/products/detail/pomona-electronics/6356-24/737678 (example)
Junk? From China? Really??
“a few milliohms”… heh, one of his leads measured 600mohms. a 0.6V drop over less than 3ft.
Imagine a USB cable like this, 1.2V at 2A charging your phone… each direction. 5V is now 2.6? That’s a dead LiIon.
I’m rather shocked how passive folk who know better are these days about such things that were once established wisdom that are now winding up in even products from once-quality names. Fine, a mouse? Sure why not. A friggin set of test leads? Next thing you know, you’ll start seeing “These MOSFETS are designed to be parallelled” in datasheets, and high-end engineers who don’t think twice about it… Oh wait, that was already a thing in 2004, and guess what failed in that $5000 TV, just months after its warranty expired. Or next you’ll buy a lamp socket from a long-trusted decent-enough hardware store at a bit of a high cost, which came to them from a long-trusted decent enough supplier with a decent enough reputation to justify a bit of a higher cost considering all that and supporting local, only to discover that it’s made like they changed their outsourcing to a startup that only just learned how to stamp sheetmetal by melting down aluminum cans in a handmade crucible in thei backyard and certainly have no expectation nor desire to be hired again for the next batch, and clearly don’t know or care enough about electricity to worry about whether their barely-compressed rivets burn down a neighborhood… And all that with a Real UL-Listing, because apparently even UL doesn’t care about their reputation enough to check second-runs. Or WE don’t care enough to ask for any sort of ongoing QC for the things that burn down homes.
Or, next thing you know, decent engineers will consider it decent established wisdom, and design new standards around, sending 2A through a friggin’ hair-thick connector in every device we use…
This world is crazy.
I already pretty much DO design around bad quality parts. Obviously, I don’t actually spec said bad parts, but if it’s practical I aim for things to work, or at least be safe, with low quality materials.
I like to add input voltage monitoring to everything, so I can detect if cable resistance is actually a problem and let the user know.
Happened to me so many times. I started soldering them out the box.
The mouse wire could be magnetic due to iron shielding?
There are also valid uses for copper clad steel in cables. Most commonly to make it more durable against bending. Including a steel braid or a steel conductor can help enforce a minimum bending radius.
Some coaxial cables have CCS core. Because of skin effect it makes no difference to RF signals, but the steel is more resistant to pulling when a long cable is hanging vertically during installation.
Solid core CCS can be a nasty surprise to your precious cable cutters.
Not just a nasty surprise. Although it seems fine, the cable will eventually rust and it will cause connection issues. I speak from experience. Before I had FTTH I had coax internet and one day the cable just, let go.
18 awg wet spaghetti insulated in kynar with silly putty affixed terminations require a few adjustments to your measurements but hey they’re cheap on Ali.
Here’s a hot tip for you:
Don’t use lead free solder on copper clad aluminum or copper clad steel.
Copper dissolves in solder. It dissolves even faster in lead free solder.
With copper clad wire, the lead free solder can dissolve the copper cladding faster than you can solder a joint. You end up with a burned mess and no joint – and a lot of frustration.
I went through this a couple of months ago when my son had some trouble soldering some wires for a university project.
https://josepheoff.github.io/posts/howtosolder-flux
Besides the copper clad aluminum wire, we also found that the no-clean flux in the roll of solder he had bought didn’t do a good job even on plain copper wire.
When you go to buy solder, make sure you get lead free solder with an activated rosin flux core rather than some no-clean. It makes a world of difference in solderability.
Don’t solder CCS and CCA, use crimp or screw terminals and solder that. Given enough time, a soldered copper cladding will detach from the core due to corrosion and mechanical stress from thermal cycling.
For that, you have to have the proper connectors and crimping tool.
All of you out there with the tools and parts for crimp on Dupont connectors, raise your hands.
(Counting…)
Zero. Right.
Use Wagos
Why would you assume the number is zero? The parts and tools are readily available and crimping makes excellent connections.
Right here I have Hozan P-707 crimping tool that works great for Dupont connectors and it’s quite affordable too. Not something you’d use for any production run, but perfectly fine for building the occasional connector.
Or in this case you might want to use a ferrule rather than a Dupont. I have right here a crimp tool for that, too, a Lodestar L214126. Again, both the tool or the wire ferrules are quite affordable.
I do, but I agree that it’s not in the average hobbiest toolbox.
Present!
I don’t use them that much but when I need them…
Aluminum works out of crimps and screws after a few thermal cycles. Spring tension (i.e. Wago or similar spring-clamp connectors) is the only hobbyist-accessible method that’s even halfway reliable.
Ultrasonic welding is the other, but it’s still megabucks.
Don’t BUY CCS or CCA. And copper does NOT dissolve in solder.
Copper most cetainly dissolves in solder.
See soldering iron tips are made of copper to conduct heat better. They are plated with iron or steel to keep the copper from dissolving.
Here’s a paper from Kester discussing copper dissolution:
https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Publications/SMTAI%202016_Paper-A%20Study%20of%20Overcoming%20Solder%20Icicling%20and%20Copper%20Wire%20Dissolution%20in%20an%20Automated%20Lead-Free%20Soldering%20System.pdf
Yes, copper dissolves in solder. Kester (and a bunch of other research and industry papers) say so.
You can prove it to yourself (or try to disprove it) very easily. Get a blob of lead free solder on the tip of you soldering iron. Hold the end of a piece of copper wire in the solder blob for a couple of minutes. You’ll see the wire has lost material when you pull it out.
If you read the blog post, you’ll see pictures from wire that was eaten by solder.
It s extremely easy to buy some rubbish today
I’ve given up buying wire or anything like that from China, much as I’ve given up expecting anything even from Amazon to be genuine.
yeah, I stopped expecting anything to “just work” or even work as intended.
Once you become knowledgeable enough on tech it feels like everything is just assembled junk that you need to keep alive somehow and do whatever you want it to.
Amazon sellers just dropship from AliExpress anyway, so…
Yes, as an example, most of the lithium ion cells there have hilariously impossible mAh ratings and they simply count on most people being unable to test them.
China being a thief/counterfeit culture is attributed to their past extreme poverty meeting capitalism, the ethics free variety that, for example, sells nutrient free baby formula in China. When such things get national attention there and, especially, international attention, the perpetrators are dealt with harshly. The guy mainly responsible for the baby formula fiasco was executed. The guys selling fake rating lithium ion cells and crappy test leads are simply ignored.
Book:
To Steal a Book Is an Elegant Offense: Intellectual Property Law in Chinese Civilization (Studies in East Asian Law, Harvard University) – 1997
One of several studies:
JOURNAL OF CHINESE ECONOMICS, 2014 Vol. 2. No. 2, pp 73-78
Call for Copy – The Culture of Counterfeit in China
by Ling Jiang
Abstract: The aim of this paper is to deepen the understanding of Chinese counterfeit phenomenon by exploring the effect of culture. Counterfeit activities are shaped by Chinese historical, social and political reasons. Intellectual property rights protections don’t have an obvious presence on Chinese soil. The discussion of counterfeit consumer behavior research via the effect of culture is provided.
Planted “lost wallet” return rate experiment by country. Note what country is at the very bottom of the resulting chart:
https://pbs.twimg.com/media/D9mk_d2UYAIpAdP.jpg
Surprised to not see Japan on that list. Saw a video where someone tested it about 50 times with a 100% return rate with money.
Au contraire, last 18650’s I bought had a shringwrap of 2000mAh or something on them, over another shrinkwrap with the actual capacity.
So I complained about the obvious fraud, got a refund, and free calls into the bargain!
I was shocked recently by a USB-C charging cable getting seriously hot with moderate current applied. Of course, I immediately binned it.
So take it as a heads up that this phenomenon appears to be present in USB cables ad well.
How amazing! Buy in CHina and de surprised
Yeah, the good old copper clad aluminium was discovered whilst PAT testing some Amazon bought cheap nasty mains extension towers, live & neutral nice copper , but the earth, nope Cu/ Al. Small cost saving for the manufacturer I suppose, nasty fake cable though
Speaker wire too has this problem. I tried soldering it and it’s less than useless, extremely thin copper cladding just dissolved.
I always used 18AWG zip cord for speaker wire. Real copper and worked well. I suppose if you’re pushing lots of amps you might want bigger cable, but that’s available as well. Easy as your local DIY center.
“Oddly, mouse cables were also magnetic”
Maybe the isolating mantle/shielding?
More likely a steel wire for strength. It doesn’t carry any current, it is just there so the copper wires don’t get pulled out.
Sure, let’s buy it for 10usd/lead on Mouser
High quality aliligator clips. https://www.muellerelectric.com/products/BU-60 Plus some high quality wire which can be sourced from old equipment or old car wiring etc. and you have good quality clips that last forever. Sure it probably costs 2-3 USD per cable but it pays for it self when you don’t have to repeat your work or worse put out a fire!
I partly blame products like Monster Cables… a 1/4″ thick mostly-plastic audio cable with 32AWG conductors, doped to look “gold”. A product of the death throes of Radio Shack.
i buy cheap crap all the time. it’s just a question of my requirements. i remember i got cheap ic clip leads and i was unhappy about it so i bought some that seemed dramatically overpriced from a relatively more reputable vendor, and they were the same exact garbage that had upset me. in my case, the problem is nothing so exotic as fake copper wire…they simply fall apart. so i just took the plastic apart and put a dab of hot melt glue as a strain relief and now they last forever.
i can understand the desire for truly high quality test leads, but for me, if i cared about a sub-1ohm resistance i would solder it. a quarter ohm is just enough to be surprising but not enough to matter for most of my uses. i’m always aware of the fact that breadboards and test leads and so on have some resistance, some intermittence, perhaps even some inductance as well. luckily most circuits i work on just don’t care.
i don’t really like the mentality that something is garbage just because it doesn’t meet as high a standard as something else. it depends what you’re doing. if you’re mountain climbing, you need a way to validate your ropes. but if you’re just holding down a tarp, the ‘counterfeit paracord’ is generally more than sufficient. one isn’t garbage because it isn’t the other. engineering 101, it is absolutely essential to know what you are really demanding of your materials. if you don’t know what your demands are, your product will fail even if you buy expensive or certified materials. of course, a lot of times all i’m demanding is “hopefully it works well enough to tell me what i did wrong, so i can learn for the next prototype”.
the thing that really gets under my skin is that if you do know you need to meet a spec and you go out and shop for it, you often just wind up paying more for the same cheap product. that’s really frustrating. i love using temu specifically because it’s all bargain stuff, there’s no suspicion in the back of my mind “maybe i’ll accidentally buy a premium product.” the opposite of amazon where you are expecting to get what you ordered but have a nagging suspicion that reality will happen instead.
fwiw i ordered a bunch of stuff from temu and the only things i got 3 different clocks that are all so defective that i would say they are fake timepieces. but almost everything else meets expectations and quite a few things are wonderful additions to my lifestyle. everyone needs to go buy the $15 melodica!!
+1. Plenty of stuff not made poorly, but it isn’t on the cheap chinese based provider sites. Get what you paid for isn’t necessarily true anymore, but from what I see it is a self inflicted wound. Fluke sells test leads. You gonna buy those or the 1/8 price Alazon set?
Haven’t had a bad product from Ali in many years. I ordered about 50 items in the last few days alone. Just ordered 50 rolls of felt tape used for wiring looms. Not going to pay 10x the price for the same product.
That “fork” meter – it measures fairly low rezistance. Does it use Kelvin method somehow? Anyone used it and have some thoughts about this instrument in general?
I have a lot of test leads (some with various clip and some with banana plugs) that I’ve had since the 70s and 80s. All made in USA, but (not suprisingly) the ones that are made the same as the cheap Chinese ones perform just the same. If you want to run current through a lead, you’ll need a larger conductor and probably a good solder connection. Don’t expect a lead made for signals to do the job of one made for carrying current. Know what you’re buying and don’t expect something expensive for a rock bottom price.
Even knowing that the cables on Aliexpress are dodgy and just buying the connectors from there won’t help. I’ve bought two lots of banana plugs from them. One the screw won’t tighten far enough to actually hold wire in, and the other the pin and insulator came as separate pieces and the former won’t fit inside the latter. OK they were both just cheap basket fillers to get free shipping and I wasn’t expecting a lot, but it would be nice if things were even vaguely usable.
That’s an excellent experiment. Matthias Wandel’s channels are truly wonderful. Test lead safety is important, but often ignored in hobby/maker circles. Even cheap, high-resistance leads can be used safely if the limits (current, voltage, clamping force/geometry, clearances, etc.) are known and accounted for.
Test leads aren’t invisible or universal. I learn this lesson again every few years. As with every other piece of test equipment, you have to know the specs, assess how they affect the test being performed, and take appropriate action.
After watching the video, I checked all of the test leads in my personal workshop and my classroom. Of 154 clip leads and 86 probe leads, only 14 were copper-coated steel (checked with a strong magnet). Those leads came with cheap multimeters. A couple hours with an LCR meter and a spreadsheet shows 20 (all from ebay) that are probably copper-coated aluminum. The rest looked good. This makes sense since the remaining leads were either shop-made with crimp connectors (using the proper tools) and high-quality test lead cable or purchased from Mouser, DigiKey, Jameco, and McMaster Carr. They weren’t cheap, but they also weren’t unreasonable given how much they impact to safety and test effectiveness. Buy once, cry once.
Insulation testing of cheap test leads would be interesting. I already test my classroom leads at least annually with an insulation tester. Between 1-3 leads fail that test each year. Students and their projects are rough on cable and damage to insulation can be hard to see.
I wondered weather good clips can be bought as good as decades old brands like Muller etc. like I own. Build them kit fashion with known wire. A search just gave me pleasing data that Digikey has Muller and others and booties in colors. Third page or so down on their listings. Those solid copper ones whip booty.
A few years ago I bought some 5 Volt, 4 Amp wall warts for a project, but I couldn’t get more than 3/4 of an Amp out of them before the voltage started to drop. I tested them and found that while the wires were marked as being 18 AWG (and later confirmed with a wire gauge) , I calculated their current capacity as being equivilant to 25 gauge copper. I cut them open and yep, tinned steel wire, probably no copper at all.
Finding good clip lead jumpers is difficult. Cheap Chinesium ones are crimped steel wire and while the more reputable US suppliers are usually made of copper wire, the alligator clips are often poorly crimped. I hate having to spend my time disassembling them and soldering the wires to the clip before I can even use them. I’ve also noticed that the wire insulation and clip covers sold these days are quite stiff and inflexible.
I sometimes find older jumpers at hamfests but I always check them with a magnet before I buy.
ive accumulated a large number of terminated jumper wires and clip leads and i know there are broken ones in the rats nest, i usually find out when something isnt working like i should and i get the meter out, or more likely use a different wire, throw the old one pack in the pile, and relive the nightmare again later on down the line.
I’m finding that on cheap clip leads, the soft plastic boots harden up after a few years, making the clips harder to open, or they boots split etc. About the same time that the crimps fail.
Anyway, I test my test leads before depending on them, and sometimes I’ve opened and soldered all the connections if I think I got a bad batch. I’ve custom made a few heavier clip leads for when I need guaranteed current capacity and low resistance.
Lol, by just seeing the sleeve of his shirt, I know this is Matthias wandel:)