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 …

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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.

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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.

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Go

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..

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I agree.

My other post along similar lines crossed.

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

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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.

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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"

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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.

Anyone?

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Re: Monitors with bricks?

There is. in french ;)

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Flame

Until I RTFA

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

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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.

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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.

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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?

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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.

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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.

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Childcatcher

Think of the kittens!

Our cat likes chewing through USB cables....

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Anonymous Coward

Re: Think of the kittens!

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

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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.

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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.

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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.

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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.

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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.

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FAIL

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?

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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?

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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.

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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...

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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.

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Anonymous Coward

Adapters?

>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.

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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,.

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Boffin

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.

*http://en.wikipedia.org/wiki/IEEE

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.

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Plugs

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.

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Anonymous Coward

The link is just a summary

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

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Anonymous Coward

Found it

It's just a 9MB doc in the whole USB 3 spec zip - http://www.usb.org/developers/docs/usb_30_spec_071012.zip

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