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I do not want all my USB-C cables to be able to handle 90W. That would make them very thick and expensive. I do not want all my USB-C cables to support the max

I do not want all my USB-C cables to be able to handle 90W. That would make them very thick and expensive. I do not want all my USB-C cables to support the maximum 40 GBps speed (or whatever it is). That would require them to have all the 19 wires and shielding and all and again, would make them expensive and short. And just imagine how much a 90W maximum speed 3 meter cable would cost... I prefer having one power cable, one fast cable and then a bunch of disposable cables for general use cases.

kragen 5y ago
USB-PD permits 100 W with 20 V at 5 A. If that's carried over just two round copper wires (I don't know whether it is in USB-C) they would need to be 18-gauge or thicker for safety—about 0.94 millimeters. If they're copper, that's about 7.3 grams of copper per meter, 14.6 grams including the return path. Copper is expensive: almost US$7/kg. So a 3-meter 5-amp DC or two-phase cable would weigh 45 grams and contain 15¢ worth of copper. You could drop both the cost and the weight by going to aluminum. If you were designing the system from scratch, you could use 3-phase AC to cut the weight by half again, and use 48 volts to cut the weight by another 58%. I don't have any idea how thick the 19 wires have to be for USB 40Gbps (GBps?) but I imagine the answer is "not nearly that thick".
- ethbr0 5y ago
  Afaik, signaling frequency is typically cross-talk limited, vs diameter limited. Think more shielding, stricter tolerances over thicker.
  - kragen 5y ago
    It sounds like you could maybe make substantial progress by just separating the differential pairs (?) by a millimeter or two of dielectric, giving you a ribbon cable, with much lower crosstalk than the round kind. Bonus points if you color the dielectric rainbow colors.
  - Dylan16807 5y ago
    I feel like it's harder than shielding and tolerances, given that longer passive cables don't seem to exist despite the very high prices people are paying for active cables.
    - kragen 5y ago
      There might be issues of attenuation; we're talking about signals in the GHz range, where you have to use waveguides instead of wires to get low losses.
- zepolen 5y ago
  Cables cost about 5$, no one would give a fuck if they cost $5.15
  - kragen 5y ago
    That's my thinking, yes.
  - Nextgrid 5y ago
    Bottom of the barrel vendors will absolutely give a fuck and will cheap out without telling you. The advantage of USB 2 is that it's so simple that it's very hard to screw it up. You pretty much have to intentionally do it if you want to create a dangerous cable. Even the shittiest cable will work with the vast majority of devices (it might slightly heat up, voltage may sag at the receiving end meaning it will charge slower, but it'll somewhat work). USB-C is significantly more complex and requires active electronics in the cable itself in some cases, and the potential for higher voltages means a faulty/recklessly-designed cable could request higher voltage from the charger and blow up whatever's connected at the other end.
    - Dylan16807 5y ago
      The chip in the cable just identifies it. Cables don't request voltages. And the cheap cables won't have that chip, so they'll support 60 watts.
Aeolun 5y ago
I prefer all my cables with the same heads to be exactly the same. Why thought it was a good idea to make them different? As if someone buying the cable will know the difference.
- pegasus 5y ago
  But then you lose the flexibility of using one port in many different ways. What we need is some standard color coding or other clear visual indicator on cables to reflect their capabilities.
  - ethbr0 5y ago
    I've opined the same before. Just put standard-colored rings (with textures, if we want to be sight-flexible) on the cables, when they're shipped from the factory. Standardize the colors through the IF, and bam, you can tell at a glance what a cable is capable of. Like resistors, except I don't think cables are likely to shrink too much in the future.
    - lmm 5y ago
      You'll never get Apple to do that though. They didn't with USB-3, they didn't with mouse/keyboard, they won't put them on their cables. And since they're the premium brand, everyone else will have to follow them.
      - Godel_unicode 5y ago
        I'm not sure why you're being downvoted, those examples are all absolutely true. There's no chance of Apple complying with a spec which doesn't meet their sense of industrial design (which there's no way this would). I will say, they're not alone. Look at Razer, for instance. Electric green is not exactly a part of the USB 3 standard.
        ethbr0 5y ago
        In which case Apple is welcome to deal with their users being confused about cables. I see this as how the market is supposed to work. If it's a cable property, then Apple can do whatever it wants with its cables. And everyone else can do what they want with theirs.
whatthehex 5y ago
That’s a very specific privilege you’ve chosen for yourself Here, allow us to setup the various assembly processes to serve you, sir
fomine3 5y ago
So the problem is that those cable aren't identifiable without special tester.
- Godel_unicode 5y ago
  They are if you buy the right cables. Just buy cables which have the capabilities you want, and are obvious to you. It's pretty easy, as long as you're willing to put about 5 minutes into the effort one time.
  - fomine3 5y ago
    Then I need to put a specification label to every cable.
    - Godel_unicode 5y ago
      Lots of angry people on this thread who don't realize cables with icons describing their function exist. You just need to look.
craig131 5y ago
By “expensive” are you talking in the $20-30 range for a single sufficiently long cable? I don’t replace cables that often but I don’t see the big deal paying a reasonable for a high throughput cable when needed.
Dylan16807 5y ago
> I do not want all my USB-C cables to be able to handle 90W. That would make them very thick and expensive. The difference between the minimum and 100W is that the cables need to support 5 amps instead of 3. That's not much difference at all considering there are data wires too. Supporting 240W requires a couple tiny components in the plug. That's also barely anything.
sudosysgen 5y ago
Cables handle 60W not by being thicker, but by allowing a higher voltage. The thickness of the cable is decided by amperage, not voltage. So when operating at 90W the cable only needs to be a tiny bit thicker and negligibly more expensive than a normal 15W cable.

kragen 5y ago

USB-PD permits 100 W with 20 V at 5 A. If that's carried over just two round copper wires (I don't know whether it is in USB-C) they would need to be 18-gauge or thicker for safety—about 0.94 millimeters. If they're copper, that's about 7.3 grams of copper per meter, 14.6 grams including the return path. Copper is expensive: almost US$7/kg. So a 3-meter 5-amp DC or two-phase cable would weigh 45 grams and contain 15¢ worth of copper. You could drop both the cost and the weight by going to aluminum. If you were designing the system from scratch, you could use 3-phase AC to cut the weight by half again, and use 48 volts to cut the weight by another 58%. I don't have any idea how thick the 19 wires have to be for USB 40Gbps (GBps?) but I imagine the answer is "not nearly that thick".

ethbr0 5y ago
Afaik, signaling frequency is typically cross-talk limited, vs diameter limited. Think more shielding, stricter tolerances over thicker.
- kragen 5y ago
  It sounds like you could maybe make substantial progress by just separating the differential pairs (?) by a millimeter or two of dielectric, giving you a ribbon cable, with much lower crosstalk than the round kind. Bonus points if you color the dielectric rainbow colors.
- Dylan16807 5y ago
  I feel like it's harder than shielding and tolerances, given that longer passive cables don't seem to exist despite the very high prices people are paying for active cables.
  - kragen 5y ago
    There might be issues of attenuation; we're talking about signals in the GHz range, where you have to use waveguides instead of wires to get low losses.
zepolen 5y ago
Cables cost about 5$, no one would give a fuck if they cost $5.15
- kragen 5y ago
  That's my thinking, yes.
- Nextgrid 5y ago
  Bottom of the barrel vendors will absolutely give a fuck and will cheap out without telling you. The advantage of USB 2 is that it's so simple that it's very hard to screw it up. You pretty much have to intentionally do it if you want to create a dangerous cable. Even the shittiest cable will work with the vast majority of devices (it might slightly heat up, voltage may sag at the receiving end meaning it will charge slower, but it'll somewhat work). USB-C is significantly more complex and requires active electronics in the cable itself in some cases, and the potential for higher voltages means a faulty/recklessly-designed cable could request higher voltage from the charger and blow up whatever's connected at the other end.
  - Dylan16807 5y ago
    The chip in the cable just identifies it. Cables don't request voltages. And the cheap cables won't have that chip, so they'll support 60 watts.

Aeolun 5y ago

I prefer all my cables with the same heads to be exactly the same. Why thought it was a good idea to make them different? As if someone buying the cable will know the difference.

pegasus 5y ago
But then you lose the flexibility of using one port in many different ways. What we need is some standard color coding or other clear visual indicator on cables to reflect their capabilities.
- ethbr0 5y ago
  I've opined the same before. Just put standard-colored rings (with textures, if we want to be sight-flexible) on the cables, when they're shipped from the factory. Standardize the colors through the IF, and bam, you can tell at a glance what a cable is capable of. Like resistors, except I don't think cables are likely to shrink too much in the future.
  - lmm 5y ago
    You'll never get Apple to do that though. They didn't with USB-3, they didn't with mouse/keyboard, they won't put them on their cables. And since they're the premium brand, everyone else will have to follow them.
    - Godel_unicode 5y ago
      I'm not sure why you're being downvoted, those examples are all absolutely true. There's no chance of Apple complying with a spec which doesn't meet their sense of industrial design (which there's no way this would). I will say, they're not alone. Look at Razer, for instance. Electric green is not exactly a part of the USB 3 standard.
      - ethbr0 5y ago
        In which case Apple is welcome to deal with their users being confused about cables. I see this as how the market is supposed to work. If it's a cable property, then Apple can do whatever it wants with its cables. And everyone else can do what they want with theirs.

whatthehex 5y ago

That’s a very specific privilege you’ve chosen for yourself Here, allow us to setup the various assembly processes to serve you, sir

fomine3 5y ago

So the problem is that those cable aren't identifiable without special tester.

Godel_unicode 5y ago
They are if you buy the right cables. Just buy cables which have the capabilities you want, and are obvious to you. It's pretty easy, as long as you're willing to put about 5 minutes into the effort one time.
- fomine3 5y ago
  Then I need to put a specification label to every cable.
  - Godel_unicode 5y ago
    Lots of angry people on this thread who don't realize cables with icons describing their function exist. You just need to look.

craig131 5y ago

By “expensive” are you talking in the $20-30 range for a single sufficiently long cable? I don’t replace cables that often but I don’t see the big deal paying a reasonable for a high throughput cable when needed.

Dylan16807 5y ago

> I do not want all my USB-C cables to be able to handle 90W. That would make them very thick and expensive. The difference between the minimum and 100W is that the cables need to support 5 amps instead of 3. That's not much difference at all considering there are data wires too. Supporting 240W requires a couple tiny components in the plug. That's also barely anything.

sudosysgen 5y ago

Cables handle 60W not by being thicker, but by allowing a higher voltage. The thickness of the cable is decided by amperage, not voltage. So when operating at 90W the cable only needs to be a tiny bit thicker and negligibly more expensive than a normal 15W cable.