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USB Power Delivery: Plugging into the Benefits
- Animats 5mo ago240 watts over a USB-C connector? What next, USB toasters and coffee pots?
- dotancohen 5mo agoThat's only a single ampre at standard European mains voltage. It's still a lot of power for those tiny connectors and insulation, but an order of magnitude insufficient for those appliances. I bet that cable gets plenty hot at 200+ watts.
- Animats 5mo agoUSB-C is limited to 48 VDC. Above about 50V, electrical safety codes apply.
- dotancohen 5mo agoYes, 240 watts is 5 ampres at that voltage - that's why I suspected that the cables get hot. I'm even surprised that a cable so thin is sufficiently insulated for 48 volts. I've seen 24 volt truck wiring arc out of dirty connectors.
- seba_dos1 5mo agoYou need a e-marked cable to get to 5A with any PD voltage, as a random crappy cable could get dangerously hot indeed. The limit is 3A and 20-21V otherwise.
- gsich 5mo agoYou sure? Those regulations go even higher. https://en.wikipedia.org/wiki/Extra-low_voltage https://en.wikipedia.org/wiki/Extra-low_voltage
- exmadscientist 5mo agoThe controlling standard is usually 62368, and the target is usually being a "Limited Power Source", which is 60V or less, and 100 VA max.
- wongarsu 5mo agoA full sized European electric kettle is about 2000 watts, but if you limit capacity to a single cup you can get acceptable performance on 200 watt. A USB-C coffee pot or kettle scaled to 0.2 liters (7oz) could work. Would be a great option for travel
- deleted 5mo ago[deleted]
- tredre3 5mo agoToasters are frequently only ~750W. That isn't an order of magnitude away from the capabilities of current USB-C. I doubt they'll ever increase the voltage beyond the current 48V (I was actually shocked that they didn't stop at 24V) so toasters are forever away. But not an order of magnitude away!
- m463 5mo agoI remember scoffing years ago at USB powered coffee warmers. Maybe the situation has changed.
- Schiendelman 5mo agoThe Ember cups could have used PD! But the cables would have been more expensive, as would have the power brick (and you would have had bad user experiences plugging into less powerful USB power supplies)
- ksec 5mo agoI mean my electric Fan and standing lamp are both powered by USB-C. There are things that shouldn't be powered by USB-C. But there are plenty of sub 100W consumer electronics devices that really should be USB-C. I waited years before Panasonic released their lamdash shavers using USB-C.
- jeffbee 5mo agoYou joke, but this is enough to make recharging an e-bike practical. E.g. https://amplerbikes.com/pages/nova https://amplerbikes.com/pages/nova
- theragra 5mo agoThis is my dream. To reverse engineer my bikes charger and create an USB pd to take with me on a self-sustained trips.
- edent 5mo agoI've basically stopped buying any portable electronics unless they take USB-C. Currently travelling with a laptop, watch, toothbrush, eReader, camera, bug-bite treater, and phone - all charging from the same power brick. I'm guaranteed of getting a replacement cable / charger wherever I am in the world if I need it. The only slight snag is some cheaper itema refuse to use PD and insist on plain 5V/2A - buy most decent travel chargers have NON-PD ports. Amusingly, most of the buses I've taken recently also have USB-C ports on them for ad hoc charging. Perhaps one day EVs will use USB-PD-Max rather than CCS :-)
- ElijahLynn 5mo agoSame! I've also returned a few USB devices that ship with a USB-A to USB-C cable and ONLY charge in that mode, they also MUST charge with USB-C PD. The two so far were a therapy light and some Zippo hand warmers. Like, who in the hell would design a device that has a USB-C port on it where only a fraction of chargers will work on it. It feels even worse than proprietary charges, because you see a USB-C port on it and think, oh I have a plug that fits it, and then it doesn't F**ing work. Idiot engineering/product teams, making the world suck with their falsely advertised USB-C ports. If anyone of you are on a team that ever makes this decision, just know that it is a stupid decision, and jump ship when you can.
- myself248 5mo agoThe thing is, making a 5v-only device PD-compliant is literally one resistor. It costs well under a penny. It's pure ignorance, not a decision, but the lack of one. Lack of caring, lack of having an actual engineer involved, just slapping an oval-shaped port into a product where a trapezoidal port had been, and blindly thinking that magically makes it spec-compliant. Or not thinking about the spec at all. I return these devices too. Lots of them. My e-commerce returns over the last year are probably 50% PD non-compliance, 50% all other defects combined.
- exmadscientist 5mo agoIt's two resistors, actually. But they cost $0.0003 each (that's 0.03¢, or just around 3,333 of them for US$1) from distributors. Though there appears to be a bit of a stock crunch right now. So... yeah. The bigger issue is not really the parts cost, it's the fact that it adds an extra part to the design that has to be purchased and tracked and assembled and blah blah blah. This is the real reason it often gets left off on the bottom-of-the-barrel products. Many times there is no other use for a 5.1kΩ resistor. And it might not even fit well at the cheap sizes (0603 or 0402), and going down to 0201-capable assembly factory flow just for these two resistors is not going to happen.
- hazkoulia 5mo agoI'm looking forward to USB-C PD small format factor PC's. A decent amount of room in the PC cases is taken up by the power supply. And if USB-C could somehow provide a range of voltages to the motherboard, SFFPC's could be downsized even more
- omh 5mo agoThere are some SFF PCs that can take USB-C power. Lenovo have some,but sometimes require adapter cards. And a few of the Chinese N150 units will take PD power It's great for hot swapping and more portable than a laptop.
- exmadscientist 5mo ago> And if USB-C could somehow provide a range of voltages to the motherboard, SFFPC's could be downsized even more You reeeeeeally don't want to do that. Cable inductance is a big deal, among other issues. You want the main DC-DC regulators on the board, usually right at the load, for the main loads. Most of the PSU bulk is for dealing with mains itself: handling 50/60Hz or mains isolation is just physically large. Getting in secondary 20V DC (or so) from a single connector and then regulating it down on board is pretty much the ideal solution. (I can't even begin to comprehend the horrors of a USB-PD negotiation involving multiple voltages. It's already the worst standard I've ever had to deal with.* Don't make it worse!) (* Not hyperbole, it is truly, truly awful. At least things like 60601 are bad because, you know, they're covering lots of stuff like lifesaving medical devices. USB-PD is... holy hell, it is just bad.)
- seba_dos1 5mo agoI quite like PD 2.0 when ignoring the legacy USB-A stuff. It's semi-elegant. 3.0 and further made it an abomination though.
- mschuster91 5mo ago> I can't even begin to comprehend the horrors of a USB-PD negotiation involving multiple voltages. It's already the worst standard I've ever had to deal with. Yeah but usually you don't have to deal with that yourself but have some sort of chipset that handles all the USB-C PD and, optionally, even data-lane muxing stuff.
- smallmancontrov 5mo agoSpeaking of which, does anyone know a line of PD Decoy modules to convert barrel jacks to USB-C without the atrocious behavior of "oh, the charger doesn't have 12V, here's 9V have fun!" that the early ones all did? Ideally I'd like a little red light to come on or something, but I'd settle for not silently browning out the device.
- miladyincontrol 5mo agoiirc theres ones that do. However I dont recall there being any clean fix to the amperage constraint issues. Especially when a lot of usb-c chargers will vary output as they heat up with usage. Which is kinda part the issue, usb-c charging bricks, they aren't usb-c power supplies, there is no expectation of sustained output capacity. Thankfully at least some the multiport ones have renegotiation more or less solved cleanly rather than what is essentially rebooting the PD controller.
- m463 5mo agosounds like someone needs to create a DC-DC charger
- smallmancontrov 5mo agoI mean, so long as it cuts off and throws a red light I'll figure it out, especially if the brick got toasty, and then I can find a new brick. My problem is that "best effort" seems to be almost universal behavior among PD triggers and it multiplies the failure modes.
- SchemaLoad 5mo agoYou ideally want to get a USB-C brick that's over specced and from a reputable brand. Like if you get a macbook 140w usb-c brick it will work fine with everything. Even for actual PSUs it's always been the advice that you want a decent amount of headroom to avoid issues.
- dotancohen 5mo agoActually, that was 5v, not 9!
- itnerd 5mo agoDoes PD include a specification that allows a client device to share its current battery level? How does Apriv know which device “needs” a high output level? > Using dual-port modules, the system recognizes that, say, one smartphone battery in the vehicle is at 5 percent of capacity and a second phone is at 75 percent. The programming module gives the former device 100W and the latter 25W.
- seba_dos1 5mo agoYes, since PD 3.1 (see "Get_Battery_Status" request).
- mtabini 5mo agoUSB-PD 3.1 provides both a Get_Battery_Cap message, which asks the sink to tell the source the capacity of its battery) and a Get_Battery_Status message, which asks the sink to inform the source about the current charge of its battery. Here's an example capture of an exchange between my MacBook Pro and iPad: https://imgur.com/a/8rZlN9X https://imgur.com/a/8rZlN9X The iPad responds to Get_Battery_Cap with Battery_Capabilities, which reports the total capacity in Wh: USB Vendor ID: 0x05AC Product ID: 0x0000 Design capacity: 280 Last full-charge capacity: 280 Battery reference: valid And then when the MBP asks for battery status, the iPad returns a Battery_Status message: Battery is present. Present capacity: 14.2Wh Charging state: charging. Later on, as the charging continues, the iPad will issue an Alert message: Reported alerts: Battery status changed. Affected batteries: Fixed battery slots: 1 And then the MBP will send a Get_Battery_Status again, and so on. (Example capture here: https://imgur.com/a/TI5maV0 https://imgur.com/a/TI5maV0 What's really cool is that this exchange happens both ways—the iPad also sends a Get_Battery_Cap message to the MBP, because it is also capable of acting as a source, and, if the laptop's battery drops sufficiently low, the source/sink roles may swap (using a DR_Swap message) so that the iPad ends up charging the MBP!
- seba_dos1 5mo agoI think you meant PR_Swap rather than DR_Swap.
- quotemstr 5mo agoI'm appreciating this recent spate of "Why Underappreciated Technology X is Good" articles. (For example, the recent EXIF one.) It's way too easy focus on the bad and foment outrage. But the world we inhabit is pretty good, and it's good to understand why it's pretty good.
- infoinlet 5mo ago[flagged]
- userbinator 5mo agoIMHO this is a classic example of extreme overcomplexity leading to fragility and regulatory capture along with increased opportunities for antiuser hostility. Practically all devices needed nothing more than +/- on a robust barrel jack, but now we have negotiable voltage (with disasterous consequences if there is a bug in the inherently software-driven process --- which will certainly happen) pushing insane amounts of current through a tiny effete connector with barely-visible pins, "authentication" schemes to enforce vendor lock-in under the guise of protection, and entire regions legally mandating this flustercuck.
- mmastrac 5mo agoThe consequences of plugging the wrong voltage or polarity into a barrel jack, most of which are compatible enough, is pretty bad. Ask me how I know.
- userbinator 5mo agoThat's still far simpler and more obvious than the insanity of USB-C. Looking at all the complaints about "noncompliance" makes it much clearer.
- Schiendelman 5mo agoThis is purely a standards problem. The working group had to say "you don't get the logo unless you do PD" and have logo. They waited a DECADE to do that, which missed the boat, and when they did it they focused on transfer speed and wattage markings instead of a single stamp.
- anon7000 5mo agoIs it? DC barrel plugs look identical to most users. Just like USB C. Only one of them negotiates the correct voltage by default in most cases. This is a non issue, IMO. Does it depend on the electronics being designed correctly? Sure, but that’s the case for all electronics, and most devices probably build on some widely-available standardized control boards from 3rd parties. As a user, I’m sooo happy that I can bring a portable battery and a wall charger, and both can recharge every single one of my portable devices. From gaming handhelds to large, powerful laptops, to wireless earbuds, to cameras, to smart watches, to flashlights. All with very different power requirements.
- sysguest 5mo agosecurity-wise, usb-c is the worst scenario device I've ever seen -- unless you're Apple, you can't make a security-boundary without infringing patent US11205021B2 for laptops, a bad-actor usb-c cable/charger can do so much more, unless your laptop has AI that can distinguish "is this signal really coming from monitor/keyboard/etc ?" I'd rather have plain-old DC adapters (or usbc to dc)
- bar000n 5mo agolots of hallucination or should i say misinformation in this article
- rpaddock 5mo agoI have found this ST Discovery kit extremely useful in figuring out what my USB-C power sources could actually supply. "The STM32G071B-DISCO Discovery board is a demonstration and development platform for the STMicroelectronics Arm® Cortex®-M0+ core-based STM32G071RB microcontroller and particularly the USB Type-C™ and Power Delivery controllers. ... The STM32G071B-DISCO Discovery board discovers and displays USB Type-C™ port capabilities such as data role, power role, VBUS and IBUS monitoring. ..." https://www.st.com/resource/en/user_manual/dm00496511-stm32g0-discovery-kit-for-usb-type-c-and-power-delivery-stmicroelectronics.pdf https://www.st.com/resource/en/user_manual/dm00496511-stm32g... Around ~$70 US now. Was around $50 when I bought mine a couple of years ago. STM32G071B-DISCO at Mouser or Digikey.
- throwaway81523 5mo agoMadness. USB C doesn't even let you control which way the power goes. Try to charge your phone by plugging in a USBC power bank? Oops, the phone is charging the power bank instead of the other way around. Sometimes you can't even make that stop without a USB-A cable. I can't imagine what kind of fools invented that.