All About USB-C: Cable Types

USB-C cables and connectors: these are controversial topics, and rightfully so – I don’t want to pull any punches. I will also show you that things don’t have to be that bad for you, as long as you’re willing to apply a few tricks and adjust your expectations.

Wild West of Wiring

You might have a bunch of USB-C cables, and they all might look exactly the same, but you’ve likely experienced that they’re not the same internally, and often there’s not a label in sight. Yes, it’s pretty bad, and one could argue it’s getting worse.

I’d like to clarify that I’m only talking about USB C male – USB C male cables here. While cables like USB-A to USB-C are popular, they are quite simple; you get USB 2.0 or USB 3.0 data and 2 A of current at most, and the USB-C plug is usually hardwired as “host, will supply five volts”, which is defined by a pullup resistor. Also, while cables like “Type-C to DisplayPort” might look like cables at a glance, they are adapters with a meaningful amount of active circuitry in them.

Purely following the specification, there used to be six types of USB-C to USB-C cables out there. Then, it became eight. Now, I’m afraid, there’s twelve of them, purely following the spec, and there’s way more when counting all the out-of-spec cables. Good news is – for most of the time, majority of these cables will be suitable for simple tasks like charging and data transfer, and situations where you need a very specific cable are going to be rare enough. Still, let’s go through it, and you’ll see that they’re easier to tell apart than it might look.

Sorting Cables Into (Mental) Boxes

For a start, there are two variations of current capability – 3 A and 5 A, with 3 A being the bare minimum for any cable out there, and 5 A support being optional. Of course, as you would guess, the bargain bin cables might be undersized for even 3 A, but most cables will pass 3 A no problem. Last year, USB-C group introduced EPR, raising maximum voltage from 20 V to 48 V, and requiring changes to cables and connectors to increase isolation between power and data pins. That’s two more categories, SPR (20 V max) and EPR (48 V max). However, there are no 3 A EPR cables, so it’s a tiny bit less confusing than it sounds.

Then, there are at least four variations of data transfer speeds. It used to be that you’d have USB 2-only and USB 3-only Type C cables, as well as Thunderbolt-certified cables. Now, there’s a new USB 3 standard which wants higher speeds, and needs higher-specced cables. Plus, there’s active USB-C cables that put the signal through redrivers or fiber optics for achieving long-distance operation. If you thought there might just some cabling variability that introduces additional small permutations inside and outside the specification, you are, unfortunately, correct.

This gives us a three-by-four matrix of “which cable you might have on hand”. Three for 3 A, 5 A, or EPR 5 A, and four for cable speeds. There’s also plenty of blatantly out-of-spec cables out there – like charging-only cables without 2.0 pins, which is blasphemous as per USB specification. Of course, you can indeed buy these by accident, or intentionally. How do you figure out which ones you have? Let’s simplify the situation to the three-by-four case and mostly dismiss the exceptions – over time, the weird cables will become less and less prominent, as even bargain bin manufacturers will learn to keep it together.

The undeniable benefit of having so many cable variations is that you can actually buy a $5 USB-C cable when you only need $5 worth of capabilities, and a $40 cable when you need $40 worth. 2.0-cables are also thinner, lighter and more flexible – you really don’t want to use a Thunderbolt cable when you want to charge your laptop on the go. Plus USB-C has  facilities to distinguish between different cables! Let me show you.

Your Cable Has A Computer In It… Almost

When a power supply is capable of providing more than 3 A over a cable, it won’t do that instantly – first, it will check that the cable can handle such a current, and that the device connected is able to accept it.

How does it check cable capability, exactly? By reading the cable’s “emarker”. An emarker is a memory chip inside the cable plug that encodes the cable capabilities and parameters, and taps into the CC channel in order to transmit them. It’s required for anything more than USB 3 speeds or 3A current, and there’s a myriad of parameters that could be encoded into an emarker, including even, ahem, country codes. Would you like to learn more? Here’s a programmable emarker (VL151) datasheet, it lists a ton of fun info you will be able to get out of an average emarker!

If you ever feel like it, you can just buy emarkers online and put them inside your cables – here’s a WLCSP VL151 in stock, and there’s also currently-out-of-stock UDFN versions of the same; you can reflash it over I2C, sadly, only three times. If you want to build your own USB-C cables with  5A support, you can also buy cable plugs with emarkers soldered onto them. One can only hope that we see Doom on USB-C emarkers soon.

Checking The Cables Ourselves

So you can check the cable capabilities by reading the emarker. Linux users might think that this information ought to have been available to you somewhere in /sys/, but apparently, there’s not all that much support for it yet – /sys/class/typec/ is empty on my Framework laptop with 6.0.3 kernel, even with a Type-C monitor plugged in. In the meantime, there’s USB-C testers that can read emarker information. Also, as this article series follows, I might just show you how to build an emarker reader yourself!

If an emarker is not present, you can assume USB 2.0 speeds and 3 A current support, but not necessarily much more than that. Apart from current carrying capability of the cable, the emarker can tell you whether the cable contains high-speed pairs, and what kind.

A USB-C cable is supposed to contain either no high-speed pairs, or four of them, in addition to the required USB 2.0 pair, of course. There are legal exceptions – if you have a USB-A to USB-C, USB 3-capable cable, it will contain only two pairs. And a USB-C to HDMI adapter with a hardwired (captive) cable is also likely to only have two pairs. Plus, in practice, I have a cable that came with my USB to M.2 NVMe enclosure that only contains two pairs. It will work for USB 3.0, but it won’t work for DisplayPort or such – it’s not long enough for that, anyway.

Do you want to check for yourself? No need to cut the cable apart, thankfully. We’ve covered USB-C testers aplenty, here’s just a recent one. It’s open-source and you can easily assemble it for yourself; otherwise, Tindie and Aliexpress have a whole bunch of ready-made ones. This will not show any differences between a 20 Gbps and 40 Gbps cable, but it will let you distinguish between 2.0- and 3.0-capable cables.

You can also test cables in vivo. If you use a 100 W charger and a 100 W laptop, you can easily check whether your cable is 100 W capable, just by plugging them together through a cheap USB-C power meter and seeing whether power consumption exceeds 3A. Same applies if you have a bunch of cables and you want to know if they do USB3 or beyond – and you also happen to have, say, a M.2 NVMe enclosure with a USB3-capable Type-C female port.

Given that, here’s a quick&dirty test – connect the enclosure to an USB-C-equipped laptop with a cable, then run lsusb -t, which will show the connection speed (480 for USB2 cables, and 5000/10000 for USB3-capable cables). As a bonus, you can check if any of your USB3 cables fail the reversibility test too – since, apparently, that’s still a problem.

Compensating For Lack Of Labels – Ourselves

Of course, the manufacturer knows the cable capabilities and exact internal structure when they build it. There are supposed to be labels, but there are hardly ever labels on the cables. Sometimes there are labels on the packaging, so, if you haven’t yet thrown it out, you might want to take note of what’s written on there – or revisit the store listing. Say, you have a cable without markings, and you’ve just determined what kind of cable it is. What do you do?

Well, you get the nail polish bottles out, and follow the proposal of [@_saljam]. It’s a coloring scheme for marking USB-C cables after you’ve learned what they’re capable of. One stripe means 3A, two stripes mean 5A. Orange is USB 2.0, blue is USB 3 20 Gbps (Gen 1), green is USB3 40 Gbps (Gen 2), yellow is Thunderbolt. I particularly like how, with this scheme, the Thunderbolt 5A-capable cables look like bees. Also, [_saljam] says this scheme is reasonably color-blindness-friendly!

That said, USB-C started fixing things. They introduced a new labelling scheme that a lot of people laughed at. However, this new logo scheme is quite simple and makes sense. If a cable supports 40 Gbps, it will have the 40 Gbps logo on it. If the cable supports 240 W, it will have the 240 W logo on it. If it supports both, it will have both logos. You might not want to paint over these logos with nail polish, but I trust you to figure something out.

USB-C In Captivity

You might have seen devices, like docks, with short USB-C cables attached to them permanently – as opposed to having a female port on the dock, and using a male-male cable. This is called a “captive cable”. Captive cables actually don’t fall under the same rules, and the circuitry required for them is way simpler, which is why they’re used on cheap stuff so often.

In short, if you want to use high-speed lanes on your device and you build a captive cable into it, you don’t need to add a high-speed multiplexer chip to support two different cable rotations – as then, it’s the responsibility of the host to adapt to the orientation of the captive cable. Plus, since the only possible CC line is hardwired, you only need one 5.1 KΩ resistor instead of two – and you don’t need an emarker, either. If you’re adding a female port with high-speed lanes to your dock, on the other hand, you do however need a multiplexer.

In a penny-pinching arrangement of selling a highly featured USB-C dock on Aliexpress for $15, that just won’t do. As a result, many cheap devices will come with captive cables, which makes things both easier and harder. On the upside, you no longer have to worry about picking the right cable to connect such a device, and it’s more likely to be standards-compliant in a useful way, just because of how simple it is to implement a captive cable. On the downside, you’re limited to the cable that’s soldered into the device, and it breaks, the whole device breaks. Also, you can’t quite extend it. Or can you?

Let’s talk about extensions the next time, as well as other kinds of USB-C cables that might or might not be specification-legal. For now, here’s something to remember – cables are meant to be easy to replace. If a cable is no longer your friend, or it’s being weird – slap a mark of shame onto it, put it somewhere you won’t be tempted to use it, and order a replacement; better yet, a few replacements. Just like with MicroUSB cables, replacing them is the primary way to make most of your cable problems disappear.

51 thoughts on “All About USB-C: Cable Types

  1. USB was good when it was just HID and bulk transfers. Now it’s like trying to make a bulk freighter out of ski jet and some used condoms (for floatation).

    1. Very poetic, and not at all wrong.

      It wouldn’t be so bad if it was just a dumb cable that has to be able to handle w amps at x speed with the pairs within y of perfectly equal length to meet the spec. And the data that goes down it is defined effectively the same way USB HID or PD is supposed to work – default to a safe minimum active state and let the devices figure it out. But its got way to many odd little caveat in the cable now that its just making life annoying. Which now I think on it kinda sounds like POE…

      About the only bit of USB-C connectors that makes sense is they should plug in boths ways up…

    2. USB was never good (c). On a serious note, I’m writing the USB-C series continuation right now, and the more I dig in, the more I see that USB-C is overwhelmingly a net good – and worth learning for a hacker. I don’t think the few already-in-the-queue initial articles will convey the sentiment well, but if there’s one takeaway I’d like you to have – if you can’t list a bunch of things that make USB-C wonderful, you’re missing out.

      If you’re a hacker, you should look into USB-C. It’s a seriously powerful standard. The surface-level troubles can create a different impression, but it was the same for old USB stuff.

      Need I remind you about a nigh-decade of hackers clinging onto serial and parallel ports, deriding USB2 for its then-complexity compared to those? About the USB 1.1 vs 2.0 woes? About The 100mA and 500mA limit problems? MiniUSB vs MicroUSB, MicroUSB-A vs MicroUSB-B, hundred proprietary cables? Proprietary charging standards? All the shitty ports? Custom resistors on MicroUSB ID pin to denote alternative modes? MicroUSB 3.0? =D

      I hope my articles will help convey what makes USB-C a genuinely exceptional standard. I’ll go further into “what makes USB-C worth looking” throughout following installments. I focused on cables, connectors and spec legality first, the latter two are in to-be-released queue, but I aim to go into a different direction from there.

      1. How about the USB C hardware the industry just refuses to make? Only recently did some company finally produce a PCIe x1 card with an internal Type E connector – after having them with one Type C external port (often with some 3.x A ports). For some reason nobody would “turn things around” to put the port on the inside for front panel C port support. The lowest they’d go on that was PCIe x2.

        I contacted all the manufacturers I could find, and posted on HaD and various other places. Dunno if a bunch of other people did. But apparently someone finally decided they were leaving some money on the table by *not* making that product, especially when all they had to do was a minor PCB change and soldering on a different connector.

        Now if someone would make a USB C ExpressCard… That’s also PCIe x1 so why not put USB C on it to get the absolute maximum out of it as can be done with desktop PCs?

      1. Cables should never be disposable by design… Even less so ones that need active smarts in them!

        I wouldn’t expect my cat 4/5/5e to run the highest speeds over the long runs, but I absolutely expect it to last! And in my experience network and phone RJ-sockets and cable do tend to last really quite well (bar the retaining clip) – I’ve ended up eventually recycling the older lower grade cables that come in with stuff over having to ditch them for being busted in almost all cases. I think one or two have failed after being run over by the wheely chair on a hard floor type situations, but…

        As do decent quality USB 1 and 2 cables… USB3 stuff on the other hand seems to always be garbage that stops working if you look at it funny after 6 months, especially the micro-b connectors, those really are awful. But even USB-C isn’t immune despite a less weedy connector end – as looks nice and has all the conductors it claims populated is about the best you get, and as its a cable with far too many conductors most cables either seem to skimp on number or quality so they don’t last well or are about as flexible as a branch…

        Also never really needed a USB tester in the past – either it was power only, or had the datalines, if it has datalines it is trivial to speed check it with any old computer and device capable of current gen USB speeds… Now the cables have so many different data lines, often their own chips as well you really can’t do without a tester…

        1. USB cables are designed to fail when mechanically stressed. To save the socket and the device.

          The USB cables in my ‘cable mess’ don’t fail. The ones I’m constantly unplugging do. Cheaper then a new phone.

          1. There I have no objection, if they are designed to fail protectively of the harder to repair and more expensive devices. Though I think Nintendo’s GameCube controller style with the inline low force disconnect are a far better solution – being resettable and rather effective at protecting the device.

            But that hasn’t been my experience with USB3, especially usb C full feature cables – the internal wires tend to be so delicate that nothing you could call stress kills them at least enough for intermittent behavior.

            (I don’t have huge experience with them, as I’ve mostly avoided USB C till very recently, but something like 90% failure rate in short order so far. Though I’ve not kept proper numbers either, so it may not be quite that bad, it just feels it. I’ve certainly spent more money and time trying to source good USB C-C over the last yearish I’ve needed them than I have ever spent on any other cable…)

  2. Since i commented in the last article how much a PITA USB-C seems, and since already so many have commented from experience how much of a PITA it’s become, I’ll comment this time with a Thank You to the author for putting this information out there. If I ever have no other option but C, I know where to look for guidance!

    1. OK got one: say I get a USB dock/hub with an inbuilt C cable to connect to the host computer. It has some C/3.0 female ports which amount to a hub… But it also has a C-Female “PD” port. Specifically it says it can be used to charge the laptop. OK… If I *don’t* want to charge the laptop through it, can I expect to be able to use a C-male to 3.0A-female adapter so I can use the PD port to connect devices? Or is it power-input-only?
      Further, I take it even though C has no specific host/device “keying,” and even though it supposedly has the ability to negotiate host/device when two hosts are connected, I *couldn’t,* say, run a USB3-male (or 2.0?) to C male cable into that “hub”‘s PD port, to connect the hub to a host with USB3/2 ports, then use the C-male connector/cable built in to the hub to connect my phone as a device (even via 2.0 speeds over c) to the computer…?
      And if that somehow *is* possible, does it mean I could connect my phone and tablet, one on the built-in cable, one on a C port, then still be able to use Android’s “host/drive” switching to choose which device acts as which without swapping the cabling, and thus, via the host/device menu, be able to also swap which unit is driving the dock’s HDMI port, and which is using the mouse?
      While this may seem “obvious” to folk used to 1.0/2.0 hubs, it’s not at all obvious *in the spirit of* C’s using the same connector on both sides. And there’s no way I can afford to experiment with numerous such hubs/docks to find one that does this, because it’s darn near impossible to think of the terms to search/look for in manuals that clearly haven’t even thought of such possibilities.

      1. a. likely power input only
        b. not guaranteed, depends on whether the PD port has 2.0 data lanes connected to your laptop (as opposed to “this is a charging port” billboard notification 2.0 lanes), and that’s just not what I’ve seen out there.
        c. > also swap which unit is driving the dock’s HDMI port, and which is using the mouse?
        this is way more complex than what USB hubs, even USB-C hubs, are capable of. They’re very much like regular USB hubs in this regard – there’s a clear host role for data, and it doesn’t happen that you’re able to change it easily. You could build an external USB muxing solution that helps you with this, however.

        1. From my understanding of the usb-c standards the answer to all 3 questions is yes.
          I understand a lot of manufacturers don’t follow specs, but they shouldn’t be considered standard as this worsen UX for all customers just to save little money. The problem is so bad that most customer don’t even know what is in spec. It’s not really the fault of the usb-if and (utopically) customers should stop buying out of spec products.
          Regarding question c, check out Dual-Role-Data, contained in usb-c spec (evolution of old OTG). This should be supported by most smartphones and from my limited experience it is.
          USB PD spec even supports independent DRD and DRP(ower), so that the power host can be the data sink and vice-versa, and it can be changed any way during the connection

          P.S. I wrote a longer, more detailed answer but it got deleted and I’m too lazy to rewrite it :(

          1. Sadly, there’s a difference between “would be compliant if done (in the correct way)” and “spec requires that this be supported in all cases”.

            Most manufacturers do support the spec, mostly, maybe even correctly. What they rarely do is support the WHOLE spec, including advanced optional bits.

            And they’re not wrong; many of those optional bits are significant cost drivers and would not be useful for the target audience. Other audiences need to find other vendors.

      2. From all the PD adaptors I have played with, the PD C female is power only. I have one of those mini mulit-adaptors that is pictured in the article and it behaves like that. The host device attaches to the captive cable, power input for charging into the PD port (it has a little lightning bolt (not a lighting bolt with arrow) symbol or DC symbol (solid line with three dashes underneath)) which charges the host device, the adaptor/hub and anything attached to it, HDMI excluded. If you plug a USB-C phone into the USB-A ports via a C to A cable, I doubt you will have HDMI out from the phone. If I can find my adaptor I will try it but I doubt it will work.

        Pretty much what you are describing you want is a USB-C KVM. With a KVM you will be able to switch between your phone and a PC or laptop with a single USB-C cable going to each. However, not all laptops/PC that have USB-C will have USB-C Display Port (DP Alt mode). That caught me out with my laptop so I can only run 2 external monitors.

  3. Even USB A to USB-C is a PITA, you can’t tell if it supports USB 3 without a flash-light and a magnifying glass to examine the USB-A connector for the extra pins.
    The USB standards body should’ve mandated an “if it fits it can do it” approach.

        1. Yeah, I don’t know why people buy cables that you can’t actually grab drawings/specs for and expect them to work. Cheap crap can be handy, but I expect it to be cheap crap.

          For stuff I expect to work, there better be a proper cable drawing available for it showing the wiring/gauges/shielding/etc.

        2. “Manufacturer ignored spec” should be reason enough to not even consider that cable anyway.

          99.9% of the ‘problems’ with Type C is due to manufacturers ignoring the spec and doing something stupid, when then breaks compatibility and causes problems.

          1. Not really. The Razer Tartarus is USB2 and has a green insert. I’ve also got “USB3” cables that have a blue insert but don’t have the extra pins and are only USB2 capable.

    1. That approach would’ve been hella expensive for users, and you’d need damn thick cables if all you wanted is to connect your phone for charging. The cable difference situation is way better than the alternative scenarios, other than labelling of some kind is paramount, and it’s sadly not yet the norm.

      1. How does one know if it follows spec? Can we even rely anymore on well-known brand names not to just relabel noname inexperienced brands’ products, without even bothering to verify it does what they claim? Remember what RCA used to be, and have you seen what it’s become? Sony. JVC. And the decade or so it took for decades of customer loyalty built on decades of quality products to get smashed to smitherines by investments in names renowned for their in-depth support, that couldn’t even support the products they stamped their name on, even if they cared to?
        Can we even begin to rely on “you get what you pay for” in this era?

      2. There are a bunch of cheap Chinese things out there with Blue 8 pin Type A port connectors, that are only hooked up as USB 2.0. I installed one in the useless cache slot on a MPC Transport T2500 (AKA Samsung X65). The listing insisted it was “USB 3.0” but of course it could only work as USB 2.0 since it was just an adapter to the USB 2.0 pins on the Mini PCIe cache slot. I tried a WiFi card in it but it wasn’t recognized, I assume the BIOS was programmed to only work with the cache cards.

        At least the USB was left enabled and I installed a 128 gig USB 2.0 flash drive in the cache slot.

        Would be nice to know why, in 2008, Samsung chose to equip a top line laptop with a CardBus slot instead of ExpressCard, also why MPC didn’t say “Hey. We’re selling some of the highest spec laptops in the USA (yours, with a bit of color changes and our logo) so WTF is with this CardBus crap in 2008?”

  4. The biggest problem I’ve found is speed, and there seems to be no correlation with the speed a cable can do and the price..

    The only answer was to buy quite a few, and test them, then buy more of the one that worked the best.

    Everybody seems to be labeling cables with their marketing departments, and not any actual test of the cable. Thus you end up (with the roughly the same priced cable) being able to do anywhere (with usb C on both ends) from 25Mbytes/s all the way up to over 1Gbytes/s with exactly the same hardware at both ends…

    The whole USB mess should be changed from a arbitrary ‘maximum’ pretend number, to an actual minimum the cable/hardware will do…

    1. The USBIF doesn’t care about minimums. They allow companies to put USB 3.0 on flash drives with write speeds that crash down to below the best that USB 2.0 can do. “Write speeds up to 30 MBPS!” Yeah, for the second it takes to fill the cache, then it’s ultra slow. If it cannot sustain a USB 3.0 write speed from empty to full, it shouldn’t be allowed to bear the USB 3.0 logo.

      1. I don’t quite agree on USB from empty to full – but you certainly should have to sustain full speed for more than the pico second of cache at that speed… After all flash controllers with wear leveling and thermal throttling can never be 100% consistent in throughput, but its reasonable to at least assume staying at greater than USB2 speed as a worse case scenario to wear the USB3 badge IMO.

  5. 2 years ago I had my work laptop upgraded to model with USB-C power and get USB-C hub. In theory it should be great experience but in practice – I waste tens of minutes every week to get it working. I have second hub already and still the same problems – mangling with connectors – this way works, this don’t, or work but not charging, blinking screen and occassionally – whole USB system fail (only 2 internal hubs visible in lsusb) impossible to recover without reboot.

  6. USB started with idea of plug and play. After years of improvement you can plug everything to everything in any direction but you need so much knowledge, equipment and luck to get play :)

  7. Great article once again from Arya Voronova, thank you.

    HaD seems to be splitting into two: there are the technical articles such as this, and there are the “look Mum what I found on YouTube” articles.

  8. A continuing problem with USB cables are ones that only contain power wires yet have official USB logos printed on them or molded into them. That is *not allowed* by the USBIF licenses.

    But there’s nobody with any legal teeth to crack down on companies manufacturing bogusly marked power only USB cables. When I find such a cable I deface the USB logos so I know it’s power only.

  9. I always wondered why they didn’t just define type-C to be essentially, two USB 3.x ports strapped back-to-back. I mean it is that, but also a CC line, and needing to track which way is up, and how to define power delivery passively at the same time.

    Imagine two USB-A ports stacked, but one of them flipped over. Then take two A cables and tape them together similarly. Now you can use your double-A cable either way around and it won’t matter. If the device on the other end can only make use of one USB port, the other is unused. PD could be negotiated via software. I guess the cable should be marked somehow, to prevent shoving too much power down it.

    Ok, so some added complexity was needed, but it seems they did over-complicate the spec (high speed muxes in case the plug is flipped over? just make it symmetric…). At least the physical plug is so much more durable than micro-USB (the previous end-all-be-all charging port)

    1. You can do that for USB 2.0 because it’s still relatively slow: just take each side’s D+/D- and shove them together, and whatever, it’s fine. It’s a routing disaster, but whatever, it’s slow enough. Can’t do it for USB 3.0, it’s too fast.

      “If the device on the other end can only make use of one USB port, the other is unused.”

      If *both* devices only use one SuperSpeed lane, they have to find out which one. You can’t standardize it because you don’t have an orientation: if you say “if you only have 1, use SS lane 0” that won’t work if the cables are crossed (lane 0->lane 1) because each side will be talking to air.

      You *could’ve* done something like that and mandated that every device takes in *two* SuperSpeed lanes (even if they can only use 1) but you’d still need some way to figure out which one you talk to.

      “At least the physical plug is so much more durable than micro-USB”

      It’s actually exactly as durable, spec-wise. It’s more durable from a practicality standpoint *because* it’s symmetric, since most people just damage the crap out of it by shoving things in wrong.

      1. > “At least the physical plug is so much more durable than micro-USB”

        > It’s actually exactly as durable, spec-wise. It’s more durable from a practicality standpoint *because* it’s symmetric, since most people just damage the crap out of it by shoving things in wrong.

        I disagree; I’ve lost two phones because the micro-USB port broke; haven’t had that happen with USB-C. Granted, it could have been poor internal mounting.

  10. I spent several months slow-charging my smartphone, thinking it was because of battery wear.
    Actually I was using another, wrong usb-c spare cable as this article told me.
    Ok then, I feel a little bit stupid now…

  11. I’ve found if something comes with a USB-A to USB-A Micro cable for charging, it’s most likely power only. I have a stack of <1m white and black cables from things like rechargable lights and such. The easy way I test is plug it into a laptop and plug the micro end into my Mooltipass. The mooltipass will only display the username and password on it's display and won't connect to the PC if it's a power only cable.

    1. I built this USB cable tester from a kit.

      It’s not “cheap,” but it works very well. It won’t do the high-wattage USB-C only stuff, but will test every wire in USB 1-3 cable, and all the 5V stuff in USB-C. It will test your data lines and also place a 1A load on your power wires and report the resistance. This has been invaluable for a product that I bundle with a USB cable for power – I was able to find a new cable to bundle that had literally half the resistance of the previous one I used (and no, these weren’t no-brand cables from ebay!)

      I’m not affiliated with the kit provider, just a happy customer (and I subscribe to their monthly magazine which I believe is well worth the cover price)

  12. Is there a way to plug in a USB-C or other USB cable to determine its specification?

    When I connect the cable, the computer is able to determine speed, power, and other parts of the cable to know what it can do. On my Mac, System Information will tell me what I’m connected to and specs to the peripheral, but not the cable.

    Like many people, I have a collection of cables. If someone gives me a cable and asks me why it’s slow in charging or speed, I have to throw up my hands. Granted, I can infer it by connecting a disk drive or some other device, but there has to be a better way.

      1. Check out the ChargerLab Power-Z KM003C. It works as described. It reports on nearly all power protocols, including PD-compatible, and supports eMarker. Tech support was very responsive when In submitted a small pile of bugs and other issues, suggestions, and questions.

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