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COMMENT PAGE FOR:
HTML USB Power Delivery: Plugging into the Benefits
itnerd wrote 1 hour 51 min ago:
Does PD include a specification that allows a client device to share
its current battery level? How does Apriv know which device âneedsâ
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 wrote 1 hour 12 min ago:
Yes, since PD 3.1 (see "Get_Battery_Status" request).
smallmancontrov wrote 5 hours 52 min ago:
Speaking 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.
tredre3 wrote 48 min ago:
The vflex has a status LED that shows negotiation status. When it
fails it will still output 5V, though, they don't seem to have any
mosfet to switch the output off entirely. [1] I don't think I've ever
seen one of those type of converters output anything but 5V upon
negotiation failure. Which one did you use that did that? Their logic
being "pick the closest available voltage" I presume?
HTML [1]: https://werewolf.us/
ianburrell wrote 2 hours 28 min ago:
Those are called trigger boards. I haven't found one with buck
converter to make 12V. 12V is in earlier PD standard so lots of
chargers support it but you have to check each charger and lots don't
say. The guaranteed solution is PPS chargers that have variable
voltage.
s0rce wrote 4 hours 56 min ago:
There are things like this: [1] haven't used it, trying to find one
for my mini pc, mostly so I can use a usb c power bank as a tiny DC
ups.
HTML [1]: https://www.adafruit.com/product/5501
smallmancontrov wrote 4 hours 53 min ago:
The description explains (in bold, multiple times) that it has the
awful behavior I am looking to avoid.
dotancohen wrote 5 hours 9 min ago:
Actually, that was 5v, not 9!
miladyincontrol wrote 5 hours 42 min ago:
iirc 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.
SchemaLoad wrote 1 hour 5 min ago:
You 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.
smallmancontrov wrote 4 hours 55 min ago:
I 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.
m463 wrote 5 hours 29 min ago:
sounds like someone needs to create a DC-DC charger
Animats wrote 5 hours 53 min ago:
240 watts over a USB-C connector? What next, USB toasters and coffee
pots?
jeffbee wrote 18 min ago:
You joke, but this is enough to make recharging an e-bike practical.
E.g.
HTML [1]: https://amplerbikes.com/pages/nova
ksec wrote 5 hours 7 min ago:
I 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.
m463 wrote 5 hours 30 min ago:
I remember scoffing years ago at USB powered coffee warmers. Maybe
the situation has changed.
dotancohen wrote 5 hours 41 min ago:
That'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.
tredre3 wrote 57 min ago:
Toasters 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!
wongarsu wrote 4 hours 1 min ago:
A 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
Animats wrote 4 hours 51 min ago:
USB-C is limited to 48 VDC. Above about 50V, electrical safety
codes apply.
gsich wrote 2 hours 9 min ago:
You sure?
Those regulations go even higher.
HTML [1]: https://en.wikipedia.org/wiki/Extra-low_voltage
exmadscientist wrote 39 min ago:
The controlling standard is usually 62368, and the target is
usually being a "Limited Power Source", which is 60V or less,
and 100 VA max.
dotancohen wrote 4 hours 32 min ago:
Yes, 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 wrote 48 min ago:
You 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.
hazkoulia wrote 6 hours 25 min ago:
I'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
ranger207 wrote 1 hour 26 min ago:
I have a couple like that in my mini rack. The problem is the power
supply: these take 65W, so I figured I could get a quality 140W
charger and power them both, but it turns out that things like
"unplugging something else" would kill their power. I had to spend a
lot more on a StarTech charger to get the performance I needed
wongarsu wrote 4 hours 22 min ago:
A lot of SFF PCs already come with a power brick. Just with a 12V
barrel jack instead of a USB-C port. Compared to that design you
really wouldn't safe much space. Though I admit that USB-C would be
convenient. Maybe with a tiny battery
dotancohen wrote 5 hours 11 min ago:
The issue is that a USB charger is not a USB power supply. A charger
does its best, but makes no guarantee of constant power delivery or
duty cycle. The power supply absolutely must provide its rated output
at 100% duty cycle.
SchemaLoad wrote 1 hour 4 min ago:
There's also the fact that devices would still need an internal PSU
to convert the 28v USB-C to the multiple voltages that all the
parts inside need. It would be smaller without the AC to DC
conversion though.
exmadscientist wrote 5 hours 48 min 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 wrote 1 hour 6 min ago:
I 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.
omh wrote 6 hours 8 min ago:
There 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.
edent wrote 6 hours 47 min ago:
I'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 :-)
seba_dos1 wrote 1 hour 38 min ago:
> 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.
Every PD port will handle non-PD USB-C consumers correctly, so not
sure why would you care about non-PD ports. There is no "plain 5V/2A"
in USB-C though, it's either plain USB (100/150/500/900mA depending
on enumeration state), 1.5A or 3A. If you want to advertise exactly
5V/2A, you need PD.
SchemaLoad wrote 1 hour 14 min ago:
I think what they mean is not PD related at all, but the fact some
cheap junk has a broken USB-C setup where it's missing the resistor
that signals a device has been plugged in and to turn on the 5v
power. While USB-A just have 5v live at all times.
If you use a USB-A to C cable the device works because it results
in a USB-C cable with an always active 5V.
seba_dos1 wrote 1 hour 0 min ago:
That's why I said "non-PD USB-C consumers", as such junk isn't
USB-C compliant - it's just USB-C shaped.
JMiao wrote 1 hour 48 min ago:
we are talking about a lightweight charging cable. you can carry more
than one. boom, redundancy. being ideological about a cable connector
is the nerdy equivalent of jony ive obsessing over macbook thinness.
TulliusCicero wrote 23 min ago:
Nah, being able to reduce to a single cable type is great.
The thing, it's not just about what cables you have at home, or
even which ones you bring on a trip. It means if you go out on a
trip with a small bag and a battery, you only ever really need one
cable. It means you don't have to think about "which cables do I
bring?", completely removing a question. That's really nice!
tredre3 wrote 1 hour 4 min ago:
Assuming your comment is only about proprietary cables that have
usb a/c on the charger side, I tend to agree. Sometimes the
device's form factor or function simply cannot accommodate usb-c
without trade-offs.
I did lose my shaver's cable whilst travelling once, so I had to go
to the barber to look presentable before a meeting. Not a big deal,
but it goes to show that it happens. Had it been USB of any
description, I could have bought one anywhere.
But then again I could have just as easily lost/broken the device
itself and be in the same situation, so shrugs.
codethief wrote 4 hours 28 min ago:
What toothbrush do you have? I've been looking for a USB-C charger
for mine (standard Oral-B toothbrush) but the only ones I've found
were from no-name Chinese brands and didn't work at all.
blacksmith_tb wrote 5 hours 26 min ago:
I'm hoping we'll see most e-bikes at least use 240W usb-c pd charging
(I figure I have about a decade until I will wish I had some assist
and buy one, so probably by then, they'll have gotten there...)
I also have assorted products that won't charge c-to-c (some from
respectable manufacturers even, like Philips), but I see you can get
little adapters with 5.1K resistor you plug into said crappy devices
to cover that, I will have to try some out.
m463 wrote 5 hours 32 min ago:
For travel I have a bunch of cables with adapters on the end (choose
usb-c, lightning, micro-usb). Can use usb-c, but have the ability to
use the others.
It has helped out in a bunch of unexpected situations (usually
someone else's device)
ianburrell wrote 5 hours 54 min ago:
I think you are confusing the devices with USB-C that require USB-A,
and devices that charge the standard USB-C 5V/3A/15W. The USB-A ones
cheaped out in including the resistors that signal legacy USB mode,
they work with the ones in the cable or adapter.
Lots of people assume that USB-C always uses USB-PD, but the basic
signalling is done with resistors. Lots of devices only need 15W, and
it is better than USB-A charging. If you want faster charging, buy
more powerful chargers.
mcsniff wrote 6 hours 1 min ago:
I'll bite. What type of watch do you have that has a direct USB-C
port on it?
margalabargala wrote 4 hours 50 min ago:
They may be talking about something like the OnePlus watch, which
does not have a usb-C port on it, but the charger device for the
watch takes usb-C.
dgunay wrote 2 hours 5 min ago:
I have one and it's such a fantastic design. When I need to
travel I just throw a tiny puck in my bag and it charges off the
same brick that charges everything else I bring.
MrBuddyCasino wrote 6 hours 1 min ago:
You can always use a âPD Decoyâ if the voltage is USB compatible.
A 5 / 9 / 12 / 15 / 20 Volt barrel plug is trivially USB powerable.
ElijahLynn wrote 6 hours 25 min ago:
Same!
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.
simoncion wrote 6 hours 6 min ago:
> I've also returned a few USB devices that ship with a USB-A to
USB-C cable and ONLY charge in that mode...
By "that mode", do you mean "1.5A @ 5V" permitted by BC, or do you
mean "3A @ 20V" permitted by non-type-C PD?
> 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.
Who in the hell would design a charger that can do Type-C PD but
can't do either pre-Type-C PD or BC? Does the charger in question
also shit the bed when a USB 1.0 device attempts to draw 100mA @
5V? I hope not! Were it me, I'd return that crappy thing for a
refund.
duskwuff wrote 5 hours 37 min ago:
> By "that mode", do you mean "1.5A @ 5V" permitted by BC
Neither - OP means devices with missing CC resistors which will
fail to charge with a compliant PD source. (The A-to-C cable
works because it provides 5V Vbus unconditionally.)
exmadscientist wrote 5 hours 36 min ago:
The A-to-C cable often does not work because the resistors are
supposed to be in there.
So if you are having complete charge failures, try a different
cable.
megous wrote 5 hours 26 min ago:
A-C cable assembly always works, CC signal is connected
within the cable to Vbus via 56kOhm resistor, but that's only
relevant to the downstream port, not to the upstream USB-A
power sourcing port which does not have access to the CC
signal. Upstream port provides power unconditionally within
some limits depending on port type (CDP/DCP/USB3.0/2.0 data
port/...).
exmadscientist wrote 5 hours 20 min ago:
That's how it's supposed to work, yeah.
But there is some trash out there in the world. A lot of
it, actually.
Some naughty cables work with some naughty chargers work
with some naughty devices. Postel's Law in action, I guess?
Usually the best place to fix it is by getting rid of the
bad cables. Usually.
mschuster91 wrote 4 hours 27 min ago:
> Usually the best place to fix it is by getting rid of
the bad cables. Usually.
No. There is no USB-C to C cable that will charge a badly
implemented device with a standards compliant charger.
That is the entire point.
An USB A to C cable is completely standards-compliant and
safe, even if it always supplies 5V on the C end - any
standards compliant USB-C device should not activate the
MOSFET on its Vbus line unless it successfully negotiates
via CC.
seba_dos1 wrote 1 hour 26 min ago:
They mean bad USB-A to C cables with no resistor on CC
line. Of course this is broken junk which will work
with some devices and won't with others. I've also seen
cables with resistors on both CC lines, which is also
broken but in a slightly subtler way.
exmadscientist wrote 45 min ago:
Right. That phrase "standards-compliant" in the above
comments is doing a lot of heavy lifting.
A lot of devices are not actually
standards-compliant. Some are close. (This may
actually be worse.)
My experience has been that if the source and sink
are broken, they are often hilariously badly broken
and it is pretty easy to figure out that they are the
problem, if not quite exactly what they've done
wrong. But if things are flaky and weird and don't
really make sense, it's probably the cable. Try a
known-really-seriously-actually-standards-compliantly
-good cable and many problems go away, even if the
source and sink aren't perfect.
(Many sources and sinks aren't standards-compliant
because, even though they easily could be, they're
trying to work around the other end not being
standards-compliant itself, because that's what
you've got to do to sell a product. So they're close
but not quite there. This is not always ideal.)
myself248 wrote 6 hours 13 min ago:
The 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.
helterskelter wrote 5 hours 25 min ago:
There's an otherwise decent shortwave radio out there that was
originally charged with a micro-usb, then they released a "new"
USB-C model...except it will only charge with a 5V brick because
they literally just swapped out the ports. Really annoying.
dabluecaboose wrote 4 hours 52 min ago:
Oh man, please tell me it wasn't the CC GP-7. I have the micro
version and have been hemhawwing about updating it.
helterskelter wrote 2 hours 52 min ago:
You mean the CountyComm? If so, I'm 99% certain that radio is
a rebranded Tecsun PL-360, which is in fact a 5V. I love
Tecsun, but why they would cheap out on the USB-C refresh is
beyond me.
HTML [1]: https://www.tecsun-radios.com/product/pl360-radio-re...
dotancohen wrote 5 hours 20 min ago:
I'd imagine that a significant portion of the shortwave radio
community is capable of soldering in the two resistors.
megous wrote 5 hours 34 min ago:
Only if the device's consumption is < 2.5W, which is what a USB
2.0 computer USB-A's data port limit is. Anything above that,
compliance gets a bit more involved and complicated.
seba_dos1 wrote 1 hour 32 min ago:
Yes, but that's the case with microUSB as well. In fact,
refusing to work with underpowered source is easier with USB-C.
exmadscientist wrote 5 hours 38 min ago:
It'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.
dotancohen wrote 5 hours 15 min ago:
These companies are not manufacturing the device PCBAs, that is
done by dedicated companies such as Flex. The PCBA
manufacturing companies have warehouses of different resistors,
and 5.1kΩ is extremely common. In fact, most PCB resistor
values are quite flexible, to save on SKUs (in practice, to
save on loading another carrier on the PnP machine) often if a
specific resistor needs a specific value then all (or most of)
the other resistors will use that value.
exmadscientist wrote 4 hours 46 min ago:
I was speaking a little more towards the AliExpress end of
things, which is a sadly high proportion of the devices out
there. For the midsize CMs and up, you're right, they've got
piles and piles of stuff and don't charge by the reel loaded.
5.1k is a surprising resistor value, a lot of modern designs
don't really have anything else in that area. I'm often not
able to combine anything with it when I'm cost reducing.
4.7k, sure, but there aren't a lot of those either... 2.2k is
just not close enough a lot of the time (or ends up as 1k),
and same for 10k. So, sadly, it often does stand alone.
dotancohen wrote 4 hours 36 min ago:
Interesting, thank you. That is an end of the market that I
have not seen.
I wonder if PD will cause a comeback of that value as more
and more legacy device refreshes move to USB-C plugs.
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