back to article USB charges up to 100 watts

The USB Promoter Group has a new ambition: using the ubiquitous connectivity standard to power your laptop while saving the planet eliminating the need for proprietary power bricks along the way. The general idea, as outlined in the newly-completed USB Power Delivery Specification, is to deliver up to 100 watts over USB. That …


This topic is closed for new posts.
  1. dfgraham

    Great idea!

    My power brick is rated at 340 watts. Only four of five USB ports to turn my GFX cards on.

    1. Anonymous Coward
      Anonymous Coward

      Re: Great idea!

      Well duh, at 100W it won't power high-power devices. But having 100W on each port would allow you to power multiple higher-power devices connected via a hub.

      My wife uses a netbook + keyboard + mouse + monitor + printer + occasional scanner + external DVD.

      100W USB ports would mean eliminating power bricks and that would both be more convenient and more efficient.

      1. Ian Yates

        Re: Great idea!

        USB-powered printers and monitors (good ones, that is). Boom! Only one PSU under my desk.

    2. Tom 35

      Re: Great idea!

      What? I can't run my kettle off my laptop USB port!

      What good is that?

      1. This post has been deleted by its author

        1. Anonymous Coward
          Thumb Up

          Re: Great idea!

          I actually just dropped a PC off to a customer today. The board had a little feature I'd not noticed (which will go unused for them :( ). It's got a IPhone4 detector/driver and it ups the juice to give it a full power charge when plugged in to the usb!

  2. jungle_jim

    I hope they up the voltage

    That's a lot of current to be slinging around....

    or perhaps i missed something?

    1. Suburban Inmate

      Re: I hope they up the voltage

      I managed to lose a monitor PSU and got a bargain on a second monitor, so I run them off the internal PSU no problem. The cables are fairly thin, but 100w constantly at for example 12v would need a pretty decent cable so as not to get too warm if coiled away somewhere underneath dust/rug/cat. That rules PoundLand out. Upping the voltage beyond 12V would involve faffing around with PSU standards, a serious obstacle.

    2. Steve Todd

      Re: I hope they up the voltage

      You missed the bit about the higher power versions delivering 12 and 20v as well as the standard 5?

      1. Anonymous Coward
        Anonymous Coward

        Re: I hope they up the voltage

        Firewire supplied 30v unregulated DC. Sounds like another catch up for USB.

        1. Piro Silver badge

          Re: I hope they up the voltage

          Yup, Firewire was an awesome standard that didn't catch on...

    3. Pypes

      Re: I hope they up the voltage

      I would have bet a penny to the pound that they were going to use 48v befor reading the article. Very surprised.

      1. Morg

        Re: I hope they up the voltage

        48V doesn't make that much sense - everything in a PC is based on 12V at most, so sure there are benefits to higher voltage, but why yet another useless converter ?

  3. Azzy

    How exactly are they doing this?

    Are they upping the voltage? (sure hope it doesn't get accidentally applied to a non-compatible device)

    If not, are they making a really beefy cord that can carry 20 amps? (that'll be awkward to handle, and more expensive to make)

    This article fails to provide any information by which we could assess the practicality of their suggestion.

    1. Dale 3

      Re: How exactly are they doing this?

      RTFA. The article provides the information, but you do have to actually read it..

      1. ssharwood

        Re: How exactly are they doing this?

        To be fair, I did add all the stuff about power modes in a revision.


  4. pith


    Sounds great apart from this:

    1. AbortRetryFail
      Thumb Up

      Re: Standards

      I didn't even need to open that to know which XKCD skit it was. :o)

    2. Schultz
      Thumb Up

      Backwards compatibilty is the key!

      This being ubiquitous USB, this standard might actually penetrate your home. Regulation of phone chargers by the EU might also help.

      Ideally, you won't even notice that you have all those compatible chargers and devices at home until holy Steve, Bill, or Linus write a stone tablet, memo, or blog on the One PSU to Replace Them All.

      1. Anonymous Coward
        Anonymous Coward

        Re: Backwards compatibilty is the key!

        A standard USB 3 power input for devices sounds like a good move, just as it has been for Smart phones (in Europe anyway).

        Having high power USB 3 output on a laptop though, sounds like a recipe for expensive motherboard failures.

    3. Piro Silver badge

      Re: Standards

      Except that didn't happen. Almost every phone now uses microUSB to charge, instead of a mess of ports we had before.

      1. KroSha

        Re: Standards

        True, but there are still several different types of microUSB. My work PDA, supplied in January, and S-E phone have a different port than LSOH's Lumia 800.

  5. jake Silver badge


    Just no.

    1. Flocke Kroes Silver badge

      Why not?

      Merging a USB hub into a laptop power brick would suit me fine. I currently have power, USB and ethernet cables tied together so they don't tangle. External 2.5" disks eat two USB ports and 3.5" need their own brick. It would be tempting to put a USB/Ethernet converter on a laptop power/hub and reduce the number of cables down to 1.

      I am surprised they did not go for 48V like PoE, or take the frequency to 1000Hz so the voltage can go higher without killing people.

      1. Phil O'Sophical Silver badge

        Re: Why not?

        > take the frequency to 1000Hz so the voltage can go higher without killing people.

        What has frequency got to do with lethality? 230v can kill you as easily at 1kHz as it can at 0Hz, 50v is unlikely to kill you at either.

        1. handle

          "50v is unlikely to kill you at either."

          However, much higher is not considered safety extra-low voltage so would require completely different connectors and higher standards of insulation for anything using it.

        2. Anonymous Coward
          Anonymous Coward

          Re: Why not?

          @Phil O'Sophical

          It's not voltage, but current that kills you. As most static shocks are multiple 1000's of volts.

          As characteristic impedance varies from person to person the voltage required also varies.

          1. The Flying Dutchman

            Re: Why Not?

            People do not have a characteristic impedance. They are not transmission lines. People merely have a (very variable, depending on lots of conditions) impedance. And the reactive component is insignificant in most cases anyway.

            And while it is technically correct that (in most cases) it's the current that kills you, it is extremely unlikely that voltages below a certain level will result in enough current to be lethal. Therefore, only voltages above this level (generally set at 48 V) are considered dangerous.

            1. Anonymous Coward
              Anonymous Coward

              Re: Why Not?

              > People do not have a characteristic impedance. They are not transmission lines.

              Oh, I don't know. Hold both arms out parallel, grab the live in the left hand and neutral in the right. You'd make a pretty good shorted ¼ wave at 100MHz...

          2. This post has been deleted by its author

          3. Phil O'Sophical Silver badge

            Re: Why not?

            > It's not voltage, but current that kills you.

            I know. It still doesn't, in general, make 1kHz more lethal than DC, for a given voltage. Unless your personal characteristic impedance is highly capacitive, I suppose. 0.1F might do it, at 50V/1kHz.

      2. handle


        " or take the frequency to 1000Hz so the voltage can go higher without killing people."

        I don't know where you got that theory from - first I've heard of it.

        1. Steve Todd

          Re: 1000Hz?

          Wasnt this one of the nasty tricks that Edison played, trying to convince people that AC power was dangerous and they should be buying his DC system? It's also to origin of the Electric Chair in the US (yup, lobbying by Edison).

        2. ranger

          Re: 1000Hz?

          This is one of Tesla's tricks -- HV running at several kHz can travel through the body without the body feeling pain: at a high enough frequency, the electricty is only skin deep (literally) as it can't penetrate further.

          One problem with this though is the body's nervous system doesn't respond quickly enough ... so even if it *should* hurt, it won't. So you can get burns, but it won't necessarialy kill you.

          So I wouldn't call it "safe", and by virtue of its effects on the body, it may even be more dangerous because you won't immediately feel the effects. At least at 50Hz it's enough to make you notice when you've touched it ...

      3. Rores

        Re: Why not?

        'or take the frequency to 1000Hz'

        Surely it's DC through a USB.

      4. Anonymous Coward
        Anonymous Coward

        @Flocke Kroes

        what you need, mate, is a desktop computer

  6. This post has been deleted by its author

    1. Steve Todd

      No, 5 amps max


  7. Richard 12 Silver badge

    Except even they are saying you'll need 5 different ones

    Because you know for certain each USB3 PDS-powered device will come with a PSU at the very lowest profile it can possibly run on. (Also, PSUs are quite inefficient when run at the low end of their rated output.)

    That said, Profile 1 (5V, 2.0A) is already in existence, most tablet chargers are rated at that.

    The new bits here are the 12VDC and 20VDC ratings - do these higher voltages need to be negotiated between PSU and device (expensive), or do you need a cable with even more cores like they did for USB3 in the first place (expensive)?

    More importantly, it won't do anything about the myriad of utterly shit "USB chargers" out there that claim 1A or more and not delivering anywhere near that, or even exploding because they don't meet any of the creepage clearance and insulation requirements. Take a look at this one.

    (I really hope that's a clone and not a genuine Apple. Possible story for El Reg?)

    I know it's not the USB Promotor Group's direct legal remit, but it is already incredibly difficult to buy a legitimate USB charger and I see this making it worse. Somebody needs to start stamping on the charlatans (and Amazon don't appear to care, I've seen so many from their 'partners' being left up after a multitude of "it exploded on me" reports).

  8. spegru

    USB3 Voltage

    I think this is about USB3 with its extra contacts that can trigger higher voltages to be used. This is how the EeePad Transformer chargers work already

  9. TheOtherHobbes

    Two words:

    Fzzzzzt boom.

  10. Christian Berger


    A usecase for USB. Now if they would only use a propper connector...

  11. defiler


    Now instead of trying to figure out where the hell my wife has left my phone charger every time she misplaces her own, I'll also have to figure out where she left my laptop charger?

    Maybe if there were some central way of delivering power at a reasonable voltage (let's say 45-50V) without getting carried away on the current, where you could just draw DC out of the wall and save all this tedious mucking about with finding chargers. Something like PoE, but maybe about the same?

    NEWS - vendor ups numbers, creates solution looking for problem.

  12. Tom 7 Silver badge

    Oooooh I'm so looking forward to supporting this

    well when I plug it in at home it works...

    I cant wait till we have to upgrade all the portable devices with micro-usb on them just so fwit in finance can plug in his incredibly stylish but audibly crap speaker dock anywhere on a whim.

    Can you get car batteries with rounded corners?

  13. annodomini2

    Going to make ultrabooks look stupid

    "Yey! I have an ultrabook that weighs 2kg!"

    "Boo! I have to carry a 5Kg PSU with me everywhere!"

    1. Daf L

      Re: Going to make ultrabooks look stupid


      You already have a heavy power brick with your ultrabook - have a look under the desk. With USB charging it should be capable to make it much smaller and you may have many places where you don't even need to bring power with you as you'd just be able to plug in to a universal USB charging socket. There's no reason why chargers would have to become bigger.

      1. BristolBachelor Gold badge

        Re: Going to make ultrabooks look stupid

        I'm sorry? If you take a 5W USB charger and make it a 100W charger it doesn't have to be any bigger, because it's USB? Surely a 100W charger is the size it needs to be to convert 100W at mains voltage to 100W at 20V? Putting a USB socket on a 100W charger will not "make it much smaller".


        1. Daf L

          Re: Going to make ultrabooks look stupid

          Who said anything about making a 5W USB charger smaller - this is about making a standard power brick that is already pushing out the required Power to run the Ultrabook smaller. With standardisation and reference designs you can expect better quality and more efficient transformers.

          You also might have the ability to use existing charging sockets, or share devices amongst a power hub, hence making it only necessary to carry the relevant cable - and therefore much smaller.

      2. annodomini2

        Re: Going to make ultrabooks look stupid

        Typical laptop/ultrabook PSU is about 100w, (yes some are bigger, some are smaller), if the psu needs to also supply 100w * Number of USB socket + Laptop requirements.

        Your PSU is going to be 200w minimum!

        The voltage isn't going to change so current needs to double, more current = thicker wires and heavier duty and/or more components = much more weight.

  14. Silverburn
    Thumb Up

    ouch! ouch! ouch!

    My 1 Amp phone charger gets too hot to hold here (it is charging a less-than-economical Galaxy note, mind you).

    What would 5 Amps per port feel like in an even smaller and more enclosed form factor?

    And if it can drive 5 Amps as a charging service, won't we overheat the batteries too? (back to the galaxy - my 3030 mAh battery can hit 50'c easily while charging at room temperature).

    While such technology sounds good, I think the "human factor" has been overlooked slightly.

    1. Steve Todd

      Re: ouch! ouch! ouch!

      The iPad charger delivers 2.2 amps without spontaneously combusting. I suspect that this says more about the quality of the Samsung charger.

    2. TkH11

      Re: ouch! ouch! ouch!

      Having a 5amp PSU doesn't mean to say it's going to run at 5amps when you connect it to your battery.

      It's going to depend on what the internal resistance of the battery is at the time and no there will be protection circuitry to either limit (or regulate) the current and if fast charging a battery, a temperature sensor attached to the battery to prevent it getting too hot (and presumably exploding).

      Your 1 amp phone charge is probably also a p**s poor design, probably sourced from China and inefficient in power conversion from input to output, with the resultant heat that is generated.

  15. Velv

    When will office desks be produced with built in power distribution of this type? Why do we still need power bricks for everything? Yes, this standard will allow us to remove some. But I'm betting the laptop charging still requires a brick.

    Every office desk has a monitor, mostly now flat panel with a brick. Why not centrally power a bank of desks with one 20v brick?

    Let's take it one step further - instead of just "cumputer" stuff with USB being powered, let's set a world standard for low powered devices. Aim to have a new voltage/amperage (power) combination available in every home, office, hotel, etc in the world. How many travellers take something that doesn't require a power brick (the hair straighteners being the obvious exception). Most devices need the power brick and a plug converter. If we can set a universal standard then we all benefit.

    This won't happen overnight. And I know some pessimistic commentards will point out flaws. This is a high level suggestion to get us started. They said it wouldn't work trying to get mobile phones onto a standard charger socket, but that's getting there, and over time the obsolete ones disappear..

    1. Hope Spirals

      I agree.

      My other post along similar lines crossed.

      So at least there's two of us that are on a similar page.

    2. Fatman

      RE: Why not centrally power a bank of desks with one 20v brick?

      Two words: Voltage drop.

      As a former looser of the juice, one thing we had to take into consideration for long runs was voltage drop. The longer the run, and the higher the current the more voltage drop was a problem. One way to reduce voltage drop, was to increase voltage. In the US (where I live) typical 3 phase power is either 120/208 volt Wye or 124/240 volt Delta. Raising the voltage to 277/480 volts Wye cuts the current needed down by half or more. Since the current flow in a circuit is a component of the voltage drop, cutting the current affects the amount of drop. It is one reason why long distance transmission lines are truly high voltage (72kV, 144kV, 230kV or 460kV). You are not going to move hundreds of mega watts at 120 or 240 volts without severe voltage drops.

      Now, a single 48V DC desktop distribution "brick" with short (less than 6 feet) cords is a different matter. And quite feasible.

    3. Anonymous Coward
      Anonymous Coward

      Monitors with bricks?

      Not sure where you're from sonny but here in Blighty every LCD monitor I've ever seen has an IEC (mains) socket on it, bar one from about ten years ago.

      THERE IS NO SUCH THING AS "amperage"

      1. Morg

        Re: Monitors with bricks?

        There is. in french ;)

    4. Anonymous Coward
      Anonymous Coward

      Power over Ethernet pretty much does all this today

      If all you need for each device is an amp or two at 48V, Power over Ethernet does it today, and so does your existing LAN cabling (hopefully). A power injector at the network centre end, and either a PoE device or a tiny DC->DC adapter at the device end. Job done.

      Everything from printers to TVs comes with a LAN connector these days. Another few cents of chippery and you can put power in through it, AND there'd never ever be a need for manufacturers or distributors to supply a country-specific power supply with the device (a country-specific PoE injector would do when there wasn't one already available at customer site).

      Why this hasn't caught on, I really dinnae know.


  16. Anonymous Coward 15

    Until I RTFA

    I wondered for a minute if they were going to put 20A down a USB cable.

  17. Hope Spirals

    Size of Desire outweighs solution advantages

    I think we can all agree that power bricks are a right royal PITA.

    This proposal is constrained because it comes from the USB Promoter Group, within that constraint it's OK, maybe - others can argue the nitty gritty.

    I'd like to see a solution that has the same ubiquity as mains power so that carrying a brick becomes pointless, ideally the outlet would then be built in to the mains socket itself - and you just plug in. Thus the source of power is not a USB socket (it's special*) - the consuming socket is ... well whatever you want USB, phono etc.

    Of course this is so much fairy dust and USB has all the traction.

    1. Richard 12 Silver badge

      Re: Size of Desire outweighs solution advantages

      I've seen a few USB power supply modules for UK wallplates, so you can get them already.

      About £20 IIRC.

      This would have the possibility of making them a lot more useful - I can see monitor, printer and netbook manufacturers jumping on this, as 'generic' PSUs are much cheaper than branding your own.

  18. Anonymous Coward
    Anonymous Coward

    What's wrong with Power over Ethernet technology?

    Why don't the device manufacturers put an Ethernet socket on (if they haven't already got one) and use it for Power over Ethernet? 50V at an amp or two, tried, tested, proven, cheap as chips?

  19. James 100

    48V and more PoE would be nice. I wonder which direction monitors will support this in - or will they support both? Having my laptop charge down the monitor cable would be nice (more or less what Apple do with the Thunderbolt displays: displayport+magsafe), but so would having the monitor powered from the desktop rather than needing its own power cord (like Apple used to with some of the G5 towers I think?).

    5A at 20V should be enough for a lot of things - laptop charging, some printers, scanners, any kind of external storage, decent USB hubs without needing a power brick or being limited to self-powered devices only. The combined laptop-charger+USB-hub route sounds good to me: I could have one at home, one at work, connect the power supply in to the network, printer etc and just have a single cable to handle.

    1. Morg

      A long time ago, many PSUs did exactly what you're talking about for G5 towers.

      It was not powered from the desktop PSU, simply just wired to the PSU in -

      This wasn't such a good idea either, considering the power cable requirements that would vary wildly with a PSU burning from 100 to 700 watts and more, and a screen that could also do the same, depending on your pick.

      20V is bad because it implies yet another power converter to bring it back to 12V - if you want to go above 12V, be at least smart enough to use a multiple for future simplicity of build.

  20. RonWheeler

    Think of the kittens!

    Our cat likes chewing through USB cables....

    1. Anonymous Coward
      Anonymous Coward

      Re: Think of the kittens!

      "Aim for the cat! Aim for the cat!"

  21. stucs201

    I still think Douglas Adams was right...

    ...when he pointed out that we don't need a new standard to solve this problem - we just need to start using the one we've already got : The 'lighter' socket found in cars. 12V, enough amps to heat metal to the point it glows.

    So, just as the socket on the mains side of the power brick is (mostly) standardised on a kettle-style plug the hardwired cable on the laptop side could be replaced by a car-style socket.

    True this means carrying slightly more than standardising the socket on the laptop - you still need a cable between the brick and the laptop. However a cable is a lot lighter than the power brick, plus if you're travelling by car for some of your journey you can charge up the laptop on the way without carrying anything extra.

    1. Anonymous Coward
      Anonymous Coward

      Re: I still think Douglas Adams was right...

      Until someone plugs it into an ancient car with the earth the other way round.

    2. Anonymous Coward
      Anonymous Coward

      "standardised on a kettle style plug"

      Except most laptops are not 'kettle leads', they are 'figure-of-eight' as earth is not required.

      1. stucs201

        Re: "standardised on a kettle style plug"

        Figure 8 on a laptop brick? Really? Every one I've seen has been a kettle lead or very occasionally cloverleaf. figure 8 I associate more with camera battery chargers and radios.

        1. Anonymous C0ward

          Re: "standardised on a kettle style plug"

          Laptops I find are mostly cloverleaf but I have seen all three. The problem with cloverleaf cables is that I've never seen them on anything other than laptops- anyone can find a spare kettle lead.

    3. Richard 12 Silver badge

      Re: I still think Douglas Adams was right...

      I strongly disagree. The car cig lighter socket is a horrible design, completely unsuited to its current purpose as the contacts are very poor and unreliable.

      How many times have you had to wiggle yours to get it working?

      1. stucs201
        Paris Hilton

        Re: How many times have you had to wiggle yours to get it working?

        Thats a bit of a personal question isn't it?

  22. Jim 70

    Either way up!

    Come on, let's have a new connection specification that means you can plug the damn cable in either way up. Surely that can't be too hard to spec.

    1. Anonymous Coward
      Anonymous Coward

      Re: Either way up!

      What about a round plug, so that there isn't a "way up"? Perhaps co-axial, with a central pin? You know, like those power sockets we have on laptops, radios...

      1. Fatman

        Re: Perhaps co-axial, with a central pin?

        Are you daft???

        Unless you are talking about AC; because if not, then you have forgotten about one aspect to DC - polarity.

        I can remember having to get one of those dammed Radio Shack co-axial adapter sets, different diameter pins. different outer diameters, etc. What a PITA!!!!!

        Then what is the voltage the dammed thing runs on? How much current does it "eat"? You certainly do not want to run a device that requires 2.5A from a power adapter that can only supply 0.5A, now do you??

        Icon says it all.

  23. Anonymous Coward
    Anonymous Coward


    >What a PITA!!!!!

    True, no such worries about USB. We don't have mini/micro/fullsize A, B fitting there, do we? And we'll not need any new adapters to handle 5A USB either.

    > You certainly do not want to run a device that requires 2.5A from a power adapter that can only supply 0.5A, now do you??

    0.5A, like a standard USB port? No, you're right. I'd want to be sure that I was using one of these new USB adaptors that could deliver 5A. I do hope they don't use the same connectors as the 0.5A ones.

  24. TkH11
    Thumb Down

    Stupid idea. USB was never designed for carrying power, leave it well alone. The connector format is totally naff anyway, it's too symmetrical, often you have to look at the connector to ensure you can plug it in.

    What happens when someone takes a 100W power supply terminated in a power USB connector and inadvertently plugs that into a standard 5V peripheral USB connector on say a laptop..BOOM..bye bye £600 laptop. Naff idea,.

  25. cortland

    Good, Quick, Cheap; pick TWO

    Over the years, there has been discussion in the IEEE* Product Safety and Electromagnetic Compatibility mailing list concerning the need to keep USB ports at SELV; "safety extra low voltage." This means not only a safe, low voltage, but a safe, low current as well, and doing so makes possible some quite inexpensive, very small cables and USB devices.


    It will be interesting to see new what practices in board and device design are needed to accommodate this use: Engineers know that when seeking to make something both good, quick, and cheap, it is inevitable that one of the three must be given up to have the others.

    Tech warning because a lot of really smart people have forgotten High School physics.

  26. Astarte


    With apologies to J. R. R. Tolkien -

    One plug to rule them all, One Plug to find them,

    One Plug to bring them all and in their Laptop fry them.

  27. Anonymous Coward
    Anonymous Coward

    The link is just a summary

    Just 2 pages, do you have a link for the full thing?

  28. Anonymous Coward
    Anonymous Coward

    Found it

    It's just a 9MB doc in the whole USB 3 spec zip -

This topic is closed for new posts.