
The humble USB cable is part of an electrical revolution - dmmalam
http://www.economist.com/news/international/21588104-humble-usb-cable-part-electrical-revolution-it-will-make-power-supplies
======
kabdib
It's going to be interesting, from a security standpoint. One of the original
cracks on the PS3 was via the USB stack. I'd not go plugging my computers or
phones into jacks that I don't necessarily control.

I can see a market for buffering devices that allow power through, and perhaps
do power negotiation for you, but that do not allow data traffic. I believe
these devices already exist. though I don't know how sophisticated they are.

~~~
x0x0
(I'm not an engineer). I a similar article; iirc android phones could be owned
by plugging them into a hostile usb connection. I wonder, though, if you
couldn't produce a simple adapter that just drops some of the pins? Maybe I
don't know enough about usb.

~~~
jdietrich
You can buy just such an adapter from the link below; Version 2 is in the
works, which will include a microprocessor to allow for full-power charging.

[http://int3.cc/products/usbcondoms](http://int3.cc/products/usbcondoms)

~~~
x0x0
thank you jdietrich

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Brakenshire
This is interesting as a contribution to the solar net metering debate. If you
have a local low-voltage DC network, perhaps backed up by a UPS, you can
charge the UPS battery using solar, and that means that solar electricity
generated on-site automatically displaces grid electricity at the retail rate.
That means that solar would only need to compete with the retail price of
conventional electricity, and not the generation cost. And solar cost is
already at or near parity with retail price in many parts of the world:

This is 2010: [http://reneweconomy.com.au/2012/solar-pv-its-cheaper-than-
yo...](http://reneweconomy.com.au/2012/solar-pv-its-cheaper-than-you-
think-58689/bnef-12)

And this is 2025: [http://reneweconomy.com.au/2012/solar-pv-its-cheaper-than-
yo...](http://reneweconomy.com.au/2012/solar-pv-its-cheaper-than-you-
think-58689/bnef-2025)

(Countries above the isobar have lower solar costs than the price of
electricity from the grid)

~~~
furyg3
Of course you also have generation costs, though (The solar panels, the UPS).

------
ams6110
One problem with low-voltage DC is that according to Watt, to achieve
equivalent power (watts) at a low voltage, current is higher. And heat is
proportionate to current squared. So you can't send a lot of power at low
voltage because you lose a lot to heat. That means low-voltage runs have to be
kept fairly short, or very low power, limiting their usefulness.

~~~
GammaDelta
Funnily enough USB's inability to work over longer cable lengths works in its
favour here. Generally we don't rely on anything working over 3 metres.

Wikipedia says "the maximum power supported is up to 60 W at 20 V, 36 W at 12
V and 10 W at 5 V" [1]. For a typical 3 metre 20 gauge USB cable 10 W power
delivery will cause a voltage drop from 5 to 4.6 V. This is within the
+0.25/-0.55 specified for USB 3 [2].

Since nobody can rely on the 5 V from USB to be exactly the charging voltage
they need, there will probably be switchmode regulators in-line anyway. Device
manufacturers will just have to spec these up a bit to accept higher input
voltage if they want more than 10 W.

[1]
[http://en.wikipedia.org/wiki/USB_Power_Delivery_Specificatio...](http://en.wikipedia.org/wiki/USB_Power_Delivery_Specification#PD)
[2] [http://en.wikipedia.org/wiki/USB](http://en.wikipedia.org/wiki/USB)

~~~
michaelt
Yeah, it's fine for USB cables. The difficult bit would be if you're planning
on cabling an entire office building from one low voltage DC source, like the
solar panels the article mentions.

If you want 60 watts at 20 v is 3A, and if you want to supply a hundred ports
with that you're going to need copper cables the size of your finger.

~~~
tanzam75
A standard is currently being developed for DC distribution in datacenters and
commercial buildings, at 380 volts.

One of the proposals for residential DC is to supply 380 volts and 24 volts.
The higher voltage would be for things like space heaters and hairdryers,
while the lower voltage would be for electronics.

------
kochb
This was posted a month ago as well, discussion:
[https://news.ycombinator.com/item?id=6591186](https://news.ycombinator.com/item?id=6591186)

~~~
jcampbell1
I find it notable that this article entirely ignores the EU's Common
Electrical Power Supply law
([http://en.wikipedia.org/wiki/Common_External_Power_Supply](http://en.wikipedia.org/wiki/Common_External_Power_Supply)),
which effectively mandated that all smart phones sold in the EU use micro USB
for power. This had a swift and noticeable effect in the diversity of
connectors in phones (basically Apple is the only maker that doesn't use micro
USB and this change happened at the exact time of the law). The emergence of
USB as The Way Phones are Charged didn't happen as a magic emergent property,
but via considered government regulation. Government: it can actually work.

~~~
icebraining
The EC memorandum was only passed after the industry had already decided on
its own to implement it: [http://www.gsma.com/newsroom/mobile-industry-unites-
to-drive...](http://www.gsma.com/newsroom/mobile-industry-unites-to-drive-
universal-charging-solution-for-mobile-phones)

------
jzwinck
This is great. Five years ago I carried on trips a phone with a proprietary
USB cable, a GPS with mini-USB, a pocket camera with a like-sized charger (and
2m lead, which I refactored), and a AA battery charger for the rest of the
stuff.

These days, bike lights charge from mini-USB (or even have integrated USB A
plugs), phones are semi-required to use micro-USB, computer mice have USB
charging and data, and I recently learned that even pocket UV water treatment
devices use micro-USB and integrated Li-ion instead of AAs now. I think the
only use I have for AA batteries anymore is a camera flash. One of the
requirements when I bought a pocket camera recently was that it charge via USB
(Sony gets this; Olympus sort of does but their cables are "special"; Canon
has one or two models).

USB power can also do wonders for places where mains power is provided only
part of the day. Those USB "power banks" are already taking off, and the more
things we can use them with, the better.

We've basically killed off the C and D-size battery, the 6V lantern, and a
bunch of other unnecessary form factors. Now let's finish the job--we can make
AAAs as obscure as AAAAs if we get USB charging remote controls, and there's
no reason we can't make smoke detectors last a full year if we get rid of
their antiquated and inefficient 9V packs.

P.S.: America, think about migrating to 220-240VAC outlets someday. The fewer
standards, the better. You can make USB wall outlets standard at the same
time!

------
_Adam
If anyone is interested in the actual technical details, check out the docs
here:
[http://www.usb.org/developers/docs/](http://www.usb.org/developers/docs/)

There's a 37.7MB zip and the USB PD specification (328 pages) is packaged
within.

In order to ensure shit doesn't melt, they'll have detectable cables for >5V
and >1.5A operation. I'm reading the spec to find out how they plan to do
cable detection. IC based, or electrical connections, or maybe something else?

------
blocke
Network engineers in campus and enterprise environments have been building a
DC network overlay for years in the form of Power over Ethernet. All of those
VOIP phones, access points, and security cameras all need DC power with UPS
backup and the network closet has become where that power is provided.

On our campus it's reaching the point where every switch we'll be buying will
soon be PoE. I imagine many places are far ahead of us on this.

What is the max cable length of USB Pd?

------
fab13n
100W at 5V means 20A. We usually recommend 4 A/m2 max for copper conductor
sections, so it would require two 5mm2 wires in the cable here. It would feel
more like a rod than a cable IMO. Anyone got an idea how they plan to address
this? Higher voltages?

~~~
kyzyl
Well they're pretty limited in what they can do. Most things you'd plug a USB
cable into are not thing you'd want to plug higher voltages into, so that
would require device-side voltage conversion which is wasteful in energy,
space and complexity.

I suspect that the 100W figure is actually just a pulsed maximum
specification. The thing is that current ratings for wires are actually
specified as a max. continuous current for a given temperature rise in the
conductor, per unit length. So blowing 3-4x the current through a conductor
for a very short time (think of flashing a bulb or moving a servo) is not a
big deal. You just get a transient heat rise. Also, most applications simply
don't require 20A. Even microwaves and kettles stay below the 15A residential
fuses. (Although they do come close. I once had a shitty basement suite with
an underrated fuse. If I ran my toaster and my kettle at the same time the
breaker would flip!)

~~~
nickff
Almost all your USB-powered devices have voltage converters with varying
inefficiencies.

It should also be noted that a switched mode voltage converter can have well
over 90% efficiency, even with large changes in voltage.

You should also remember that those microwaves and kettles are getting up to
15A @ 120VRMS continuously, which works out to 1800W. You can verify the
actual power output of a kettle by timing how long it takes to boil a liter of
water, and calculate power from this time and the specific heat capacity of
water.

~~~
kyzyl
There are some practical limits to voltage conversion if you want to keep that
high efficiency. Probably most important is that your switching frequency
shouldn't be as high as it is in most small devices (because high freq. allows
you to use smaller components).

In any case, as dfox mentions, most internal voltage level conversions won't
be switched, because it adds complexity. They will be some form of linear
regulation s.t. they can move between logic levels. That's different than
moving from whatever high voltage is on your 150W USB line into a level that
won't fry CMOS circuitry. There's a reason that the wall-->DC plug conversion
usually happens in a brick on your power cable. Switched mode will be used as
sparingly as possible, such as when you also need AC signals rectified, if you
need both buck and boost depending on a battery or something, or if you need
to be able to modify the control loop dynamically.

> those microwaves and kettles are getting up to 15A @ 120VRMS continuously,
> which works out to 1800W

Well that's kind of my point. Even at 1.8kW those devices don't need to draw
20A continuous (or even pulsed, because of the fuse). Basically no matter what
you're doing, the copper losses are roughly fixed by the hardware. What you
can control are heat dissipation and current levels, and it's a lot more fun
to play with Ohm's law than try to fight against thermodynamics.

------
zhte415
In 2006 China demanded all mobile telephone manufactures to standardise on USB
connections for charging and data transfer. South Korea did so a year earlier,
requiring 'standardized charging' without explicitly stating USB. [1]

I'm curious if or how this requirement had any impact on charger
standardisation. The Chinese market combined with economies of scale for
common production models could have outweighed any cost benefits a market for
chargers could have brought.

[1] [http://news.softpedia.com/news/Chinese-Government-Demands-
US...](http://news.softpedia.com/news/Chinese-Government-Demands-USB-Access-
Mobile-Phone-Chargers-43092.shtml)

------
pkulak
Anyone know how this standard actually works? I think right now Android phones
tend to short the data lines and Apple uses some system of voltages to
communicate that it's high power, which means that the other device usually
gets stuck pulling 0.2 amps. How does this new standard tell the device it can
supply 100 watts? And does this mean that iOS and Android will be stuck on 0.2
amps? Can you plug a legacy device on at all?

~~~
em3rgent0rdr
[http://www.usb.org/developers/powerdelivery/](http://www.usb.org/developers/powerdelivery/)

USB has both power and data lines. This new standard can use data lines to
negotiate power delivery, I believe. I'd expect will still be backwards-
compatible of course. I would think the only allowable voltage would be 5V, as
is currently.

~~~
srinivasanv
100W at 5V would be a 20A current, which is sort of high.

[http://www.usb.org/developers/powerdelivery/PD_1.0_Introduct...](http://www.usb.org/developers/powerdelivery/PD_1.0_Introduction.pdf)
Page 9. There will be different voltage levels: 5V, 12V, and 20V.

~~~
em3rgent0rdr
yup, I had read that and corrected exactly same time as you :)

------
simcop2387
With the new USB Power Delivery spec this can finally make sense to really
start thinking about. Being able to power things that are "non-trivial" as far
as power goes would make this go a long way. Imagine your sound system being
powered off of a very clean DC power source, would be an audiophile's dream.

20V and 100W would make for a lot of nice options for powering things.

~~~
quesera
> 20V and 100W would make for a lot of nice options for powering things.

Requires a pair of 17AWG stranded wires for a 2m run, allowing 3% cable loss.

For comparison, cat6 is 23 or 24AWG stranded, and US residential power wiring
is typically 12 or 14AWG solid core. Smaller numbers are bigger, less flexible
wires.

I guess it won't work with microUSB contacts, or at least not at full power.

------
perlpimp
On wikipedia I can count at least 6 different types of connectors for
different voltages/current, sounds like a deal breaker to me.

I'd rather have devices adapt Power over ethernet which requires just one
cable and gives many more opportunities for networked future of devices.

in fact
[http://www.commercialintegrator.com/guide/product/details/po...](http://www.commercialintegrator.com/guide/product/details/poe_to_usb_chargers_it_chrg_p2u_it_wpchrg_p2u)
[http://www.creativeplanetnetwork.com/the_wire/2012/06/14/fsr...](http://www.creativeplanetnetwork.com/the_wire/2012/06/14/fsr-
powers-up-for-infocomm-2012-with-new-poeusb-charger-for-ipad/)

So I think R45 is a better standard to rely on, that it does have option to
carry networked data and intelligently carry voltage to charge usb powered
devices.

you can already get RJ45 hubs on the cheap too, ones with 8 ports and such.

~~~
kalleboo
We'd need a "micro-RJ45" to get any adoption among portable devices such as
phones or tablets. And some solution to those terrible plastic clips.

------
skreech
Disregarding the flamboyant visions of an electrical revolution, just having a
flippable physical interface (and hopefully not in three different sizes, two
of which always gets mixed up) would be a huge enough leap forward for
everyday life.

------
legulere
They forgot to mention the most important thing about the system from Moixa:
It's variable voltage and devices generate the needed stable voltages
themselves.

------
imahboob
love USB.. now I don't have to go looking for a compatible charger or
connector when ever I lose mine

