4 ms·

USB-C Power Supply Pushes Almost 2 KW

25 points by mvdwoord 3y ago

sand500 3y ago
What is the max power as per the USB-C spec and what is the max power the connector can handle?
- bjoli 3y ago
  I just asked a similar question. USB-pd allows for 240w. That seems bonkers.
- beefnugs 3y ago
  Its actually a total clusterfuck: (particularily power pass-thru usbC-PD hubs) 60W over cheap garbage cables 100W over special "smart" cables with chips in them higher watts devices are just being released now (these values do not include the 15W or so the hub itself needs) there are major bugs in both computer firmwares and usbC hubs where special "safety cutoffs" are being triggered in devices so you need to power cycle hubs (not just computer) sometimes, sometimes computers will freeze during boot sequence because of a usb-pd glitch (no mention that manufacturers even care about these bugs in their bios release notes)
bjoli 3y ago
Tengentially, a question: USB PD iis supposed to allow you to use USB-c for up to 240w, but I start feeling uncomfortable at way lower wattages. The connector just seems too small and flimsy. The wires are fine, so much I understand, but is it really sensible?
- lxgr 3y ago
  240W are reached using higher voltages (48V@5A), not higher currents, compared to 100W (20W@5A). The only real concern is arcing while making or breaking a connection, and the 48V mode has special provisions to avoid that, including the cable having to have provisions to make the the control pins are disconnected before the power pins to give the power supply time to lower the voltage.
  - jackvalentine 3y ago
    I know very little about USB-C or PD. Two of my laptops give me a physical 'buzz' sensation when charging via USB-C. Is this because they're not grounded? Should I be worried about the issue at higher wattages?
    - lxgr 3y ago
      Most USB-C (and other laptop chargers, for that matter) are of the double-insulated/"Class 2" variety. This means that they're galvanically separated from the primary circuit and not grounded to a protective earth conductor. For EMI reasons, there needs to be a connection (via a very small capacitor) to the primary side. This creates a measurable, and as you've noticed sometimes even physically detectable, voltage leak from the primary side, but is completely harmless since it can't actually sustain any meaningful current. More details here: https://electronics.stackexchange.com/a/216967/23924 https://electronics.stackexchange.com/a/216967/23924 If it really bothers you, you can get a three-prong USB-C power adapter. These can just ground the EMI to protective earth, and you won't feel anything. You can convert most Apple laptop power supplies into one by using a properly grounded cable, for example; they have a grounding connector (which is not connected to anything using the regular duck head adapters, though – hence the phenomenon of "buzzing MacBooks"). The phenomenon of being able to sense it using your fingers is called "electrovibration" and is actually quite fascinating. There's research into being able to use it as a form of haptic UI feedback!
      - rubatuga 3y ago
        If you want a three-prong USB-C power adapter, options include Apple, Dell and HP.
        jackvalentine 3y ago
        Found this one just before - https://satechi.net/products/6-port-gan-charger https://satechi.net/products/6-port-gan-charger
Arrath 3y ago
To be fair this appears to be a power supply that feeds a multitude of USB devices at once, instead of pushing that full amount down a single amazon basics cable. Still having trouble imagining a use case for a supply that can fast charge a dozen business laptops at once, though.
- jazzyjackson 3y ago
  slow charge ur Tesla in a pinch
- Pet_Ant 3y ago
  How about... fast charging a dozen business laptops? A charging station at a conference or a convention or a media event. Other things charge over USB such as cameras and various other sensors. I could see it being used in remote outputs that researchers charge up at, and then head out to the field for the day. That amount of charging isn't really alarming if you spread it out over many wallworts. In this case, hopefully it's more efficient being in one single unit.
thebruce87m 3y ago
My car chargers at 7kW at home.
- lxgr 3y ago
  Using USB-C? That must be a new PD mode!
  - thebruce87m 3y ago
    No, but it’s crazy to think how much power this is. Clearly this was lost on the downvoters.
efitz 3y ago
Here come the USBC hair dryers and space heaters.
- hulitu 3y ago
  And house torchers.

25 points by mvdwoord 3y ago

sand500 3y ago

What is the max power as per the USB-C spec and what is the max power the connector can handle?

bjoli 3y ago
I just asked a similar question. USB-pd allows for 240w. That seems bonkers.
beefnugs 3y ago
Its actually a total clusterfuck: (particularily power pass-thru usbC-PD hubs) 60W over cheap garbage cables 100W over special "smart" cables with chips in them higher watts devices are just being released now (these values do not include the 15W or so the hub itself needs) there are major bugs in both computer firmwares and usbC hubs where special "safety cutoffs" are being triggered in devices so you need to power cycle hubs (not just computer) sometimes, sometimes computers will freeze during boot sequence because of a usb-pd glitch (no mention that manufacturers even care about these bugs in their bios release notes)

bjoli 3y ago

Tengentially, a question: USB PD iis supposed to allow you to use USB-c for up to 240w, but I start feeling uncomfortable at way lower wattages. The connector just seems too small and flimsy. The wires are fine, so much I understand, but is it really sensible?

lxgr 3y ago
240W are reached using higher voltages (48V@5A), not higher currents, compared to 100W (20W@5A). The only real concern is arcing while making or breaking a connection, and the 48V mode has special provisions to avoid that, including the cable having to have provisions to make the the control pins are disconnected before the power pins to give the power supply time to lower the voltage.
- jackvalentine 3y ago
  I know very little about USB-C or PD. Two of my laptops give me a physical 'buzz' sensation when charging via USB-C. Is this because they're not grounded? Should I be worried about the issue at higher wattages?
  - lxgr 3y ago
    Most USB-C (and other laptop chargers, for that matter) are of the double-insulated/"Class 2" variety. This means that they're galvanically separated from the primary circuit and not grounded to a protective earth conductor. For EMI reasons, there needs to be a connection (via a very small capacitor) to the primary side. This creates a measurable, and as you've noticed sometimes even physically detectable, voltage leak from the primary side, but is completely harmless since it can't actually sustain any meaningful current. More details here: https://electronics.stackexchange.com/a/216967/23924 https://electronics.stackexchange.com/a/216967/23924 If it really bothers you, you can get a three-prong USB-C power adapter. These can just ground the EMI to protective earth, and you won't feel anything. You can convert most Apple laptop power supplies into one by using a properly grounded cable, for example; they have a grounding connector (which is not connected to anything using the regular duck head adapters, though – hence the phenomenon of "buzzing MacBooks"). The phenomenon of being able to sense it using your fingers is called "electrovibration" and is actually quite fascinating. There's research into being able to use it as a form of haptic UI feedback!
    - rubatuga 3y ago
      If you want a three-prong USB-C power adapter, options include Apple, Dell and HP.
      - jackvalentine 3y ago
        Found this one just before - https://satechi.net/products/6-port-gan-charger https://satechi.net/products/6-port-gan-charger

Arrath 3y ago

To be fair this appears to be a power supply that feeds a multitude of USB devices at once, instead of pushing that full amount down a single amazon basics cable. Still having trouble imagining a use case for a supply that can fast charge a dozen business laptops at once, though.

jazzyjackson 3y ago
slow charge ur Tesla in a pinch
Pet_Ant 3y ago
How about... fast charging a dozen business laptops? A charging station at a conference or a convention or a media event. Other things charge over USB such as cameras and various other sensors. I could see it being used in remote outputs that researchers charge up at, and then head out to the field for the day. That amount of charging isn't really alarming if you spread it out over many wallworts. In this case, hopefully it's more efficient being in one single unit.

thebruce87m 3y ago

My car chargers at 7kW at home.

lxgr 3y ago
Using USB-C? That must be a new PD mode!
- thebruce87m 3y ago
  No, but it’s crazy to think how much power this is. Clearly this was lost on the downvoters.

efitz 3y ago

Here come the USBC hair dryers and space heaters.

hulitu 3y ago
And house torchers.