Hacker News Reader

Comment by rektide | Hacker News Reader

I was going to criticize & point out how usb-c chargers at and over 100W are just so small, but there's a photo comparing it to an iphone & ok, it looks adequately impressively dense! (I have a >2 year old 100W charger that is 66x64x30mm, this 250W unit is 170x50x25)

It's been such a great synergy. Energy efficiency has been a concern already yes, but I really view usb-c chargers as pushing the consumerization & massification & development of this technology to the superb, common, un-exotic levels it's come down to. We just got tired of doing less good, actively explored trying to use a somewhat harder to drive switching semiconductor, & have reaped great rewards. Miniaturization mandated optimization & we all win. I really think the interchangable-parts/modularity & resulting competition that usb-c begot started this ball rolling.

(Hoping USB-PD, with it's bump from 20 up to 48V, once again proves another huge win!)

View on HN

I'd also point to Google's Little Box Challenge[1] as an interesting data-point of yore.

Little Box Challenge went the other direction: instead of taking AC and producing DC power, it was an inverter that took DC power and produced AC output. It had to output 2kW and be smaller than 655 cubic centimeters (cc's). The winning Red Electrical Devil's team got 3x more dense than this[2]! 240 cc's! While inverting 2kW of juice. Second place was 340ccs.

I don't know whether we'd argue this DC->AC is harder/easier than an ATX supply (AC->DC) (probably not?) but this was quite an impressive competition, almost a decade ago, that resulted in probably some of the most power-dense, highest-efficiency power conversions that humanity has ever gotten up to. For compare, this 250W unit is 212cc's. 8x less power conversion, 88% the size.

The Little Box Challenge designs were published, so there's a ton of great reading. Alas, Google frakking let the damned site bitrot off the net?! Sooo, head to archive.org[3] to read the team's writeups. From the winning CET Red Electric Devils writeup:

> GaN transistors have many very interesting electrical characteristics (low Rds_on, low Qgate and Cds, ultra low Qrr); these create technological advantages over current MOSFET and IGBT devices (small size and low production costs). Unfortunately, they also have serious drawbacks due to their very fast switching characteristics: they are challenging to drive and require sensitive electromagnetic noise management. Another pitfall is the high voltage drop due to the reverse current when the GaN is turned off. The solution selected to overcome these difficulties is to control all the GaN transistors using soft switching for the entire operation range.

[1] https://news.ycombinator.com/item?id=8070215 (271 points, 8 years ago, 138 comments)

[2] https://ai.googleblog.com/2016/02/and-winner-of-1-million-li...

[3] http://web.archive.org/web/20171006105655/https://littleboxc...

> I don't know whether we'd argue this DC->AC is harder/easier than an ATX supply (AC->DC)

The little box challenge was significantly harder, primarily due to the ripple requirements on the DC side. This is not an issue in the same sense in the AC->DC case, because you don't have that problem there (you have other ripple considerations that might look similar, but are not (PFC and ripple on the output)). Usually you would require a lot of capacitance to solve the ripple issue for DC->AC and the winning team had a very interesting way of solving it without the use of very large capacitors.

I'm doing an EV conversion, and have trouble wrapping my head around the idea that a motor controller that weighs about ten pounds or so and isn't much bigger than a loaf of bread can handle about 100 kilowatts of power, converting DC at around 140-180 volts from the battery to 3-phase AC. And that's a relatively low-end inverter.

the answer is liquid cooling. these Little Box and ATX power supplies have to rely on passive cooling (radiative, conductive, and convective) which is generally proportional to surface area == physical size ^ 3. if you halve the size, then, you lose 87.5% of the surface area! that's why these things can't shrink as much. but ultimately the silicon involved is miniscule.

It would also be worth noting that a typical EV doesn't have to run at anything close to 100% load for extended periods of time.

What sort of power an electric drivetrain can handle for a burst of acceleration lasting a few seconds versus what that same drivetrain can handle as a continuous load are two very different things.

The same even applies with combustion powered cars too, if you look at the pickup truck market you'll see massive power numbers on every manufacturer's diesel pickups. If you look at their chassis-cab commercial trucks those same diesel engines are often derated by 30-50% compared to the pickups even while being equipped with larger cooling systems. That's because the commercial variants are rated to perform to spec all day every day where the pickup version just needs to put a grin on the owner's face when they floor it off the line and then occasionally tow a boat or something.

Technically my motor controller can be passively cooled too, it's just not recommended. (It automatically goes into a low-power "limp" mode rather than burn itself out.)

I'm not sure how much power it can handle continuously in a pure passive-cooling mode.

Not to detract from your point, but surface area scales with size ^ 2.

> I don't know whether we'd argue this DC->AC is harder/easier than an ATX supply (AC->DC) (probably not?) but this was quite an impressive competition, almost a decade ago, that resulted in probably some of the most power-dense, highest-efficiency power conversions that humanity has ever gotten up to.

The LBC was misshapen because they had an odd requirement: Be single-phase. A three-phase inverter (or rectifier) naturally has low DC ripple and is both more compact and more efficient than a single-phase inverter at all power levels. All of the winning solutions had extra energy storage elements which added inefficiency and bulk which a three-phase inverter would not have needed.

With that in mind, the LBC was a little silly. A three-phase machine at the same power level would have been much smaller than any of the "winning" designs.

A high-efficiency ATX power supply has additional requirements that the LBC didn't need to meet: Isolation. This implies the use of a transformer to protect the low-voltage DC side from the AC side. They typically accomplish this by rectifing AC, using a transformer-isolated unidirectionally optimized DC/DC supply to 12V, and then provide a handful of lower-power DC/DC converters to derive the other voltage levels used by ATX. A modern unisolated DC->AC machine is effectively symmetric in its power flow, and also functions as an AC->DC machine.

One of the things I only recently learned is modern power supply’s aren’t using the transformer to knock down “raw mains” 60hz AC. Modern switch mode PSU’s in-fact rectify the AC to DC and then chop it up at a much higher frequency.

By using a higher frequency, the transformer can be much smaller and more efficient. If they were doing mains 60hz AC the transformer would be substantially larger.

I forget if they also step the supply side DC voltage up too…

> I forget if they also step the supply side DC voltage up too…

They do, but they don't have to. The front-end rectifier boosts the voltage up to 400-450 VDC. This way, most of the components can be optimized for a single world-wide compatible machine that is capable of rectifying 230VAC.

In principle, you could squeeze out a bit of efficiency (or cost) by producing a North American market machine that was optimized for 120V and a separate machine optimized for 208/230V. In practice, supply chain simplification reduces overall per-unit costs, so just about everything is designed as a single machine for world-wide markets. Only the plugs change. For ATX, only the cord shipping in the box changes.

The interesting thing about gallium nitride is its use in blue LEDs (light-emitting diodes), which was discovered in 1972 and perfected in 1993, resulting in a Nobel prize.

https://en.wikipedia.org/wiki/Light-emitting_diode#Blue_LED

I wonder what new engineering knowledge has emerged about gallium nitride that allowed it to become such a recent force in power supply electronics.

I didn't know that gallium nitride is transparent.

https://en.wikipedia.org/wiki/Gallium_nitride

It's effectively process technology improvements that allow gallium nitride devices to become less defect prone.

It's been known for some time that GaN has a superior electron mobility number (which, effectively means you can get a better/smaller/lower impedance/faster switching device depending on which tradeoff you want). Problem is, getting reasonably good process control has been challenging. It appears some folks in the industry have been overcoming that challenge, therefore we're seeing the results of that.

I've found high-wattage USB-C chargers to have very poor reliability. All the 18-W chargers I've owned have lasted multiple years, but the compact 90-W+ chargers have a lifespan measured in months.

Of course, they all purport to offer a warranty, but if you try to claim, they will not honor it. They will claim it's because you bought from Amazon and they don't warrant Amazon purchases (despite this being their main retail outlet, and the fact that they advertised the warranty IN the Amazon sales materials). Or something similar.

I have a ravpower, a hyper, and just bought the new ugreen. The ugreen is too new to judge, but the others have ran for over two years, and a good amount of that time has been outdoors in the sun.

I constantly expect failures. This seems like an absurd task I'm putting them up to. But they are all still alive & doing the job.

I've had a kill-a-watt so I can see their power consumption. A large amount of their life is spent ~60 watts, but there's definitely hours on end & heavy usage days, where they go up to or stay at 90+.

My anecdotal data looks different than yours.

My Ravpower device died within 8 months, and they refused to honor the warranty, giving as the reason that the purchaser of record was Amazon LLC, not Ravpower. Even though they advertised a warranty on their Amazon page, which was the main way they sold the devices.

Does Amazon not honour the warrenty in that case? I've never had to deal with a similar situation but I kind of figured that Amazon would do something if the page advertised a warranty and the company refuses to honour it.

I have never been able to get Amazon to honor a warranty when the manufacturer refused, even though the law in my country clearly says the retailer is responsible in the first place. In fact the button to return a product disappears from the order after a couple months, and they don't even have a category in their support system for this.

Talk to Amazon customer service and tell them you'd like to make a claim pursuant to consumer rights law.

... dreams of the EPA obtaining warrants for the fraud on the public for the disposal costs of so much wasted electronics...

I smell a class action.

In the EU you get 2 years warranty for all items from every retailer by law, and most generally honour them.

So this is a very frequently repeated misconception about what the EU law actually says.

Yes, there is an EU law that says retailers are responsible for 2 years(6 in a some cases) for any item they sold......but only to rectify any manufacturing defects. The law additionally states that any defect found in the first 6 months is presumed to be a manufacturing issue, anything after the first 6 months it's the responsibility of the customer to prove that the product has failed due to a manufacturing problem. I'm sure you can appreciate that this can be very hard to do.

It's not a "warranty" in the sense that most people mean warranty. If your laptop fails 18 months after purchase, the retailer only has to fix it if you can prove that it failed due to a manufacturing defect. It's different to manufactuer's warranty, which usually covers any defect no matter the reason.

And yes, there is also the law that states that products should last a "reasonable" amount of time - but what is reasonable is not a strict definition, and again, unfortunately sometimes has to be argued in small claims court. It's not so straigtforward.

However, in practice most good retailers do not make a big deal out of the burden of proof as long as there is no visible damage that could cause the issues.

I have used warranty frequently after 6 months and never had to prove it is a manufacturing defect. Of course, if you buy at some shady webstore or known-bad retailer, you might have more issues.

These are not EU laws, they are EU directives directing the member countries to implement laws. But these laws are not all the same, for instance in how much effort a customer has to make to ‘prove’ that a device failed due to a manufacturing defect.

I agree - I wonder why Chinese junk that basically barely works and not for long even then has managed to establish such a strong foothold on the retail market (particularly Amazon). I had the same experience - moreover my charger had multiple ports, but as soon as you plugged more than one thing into it, the wattage would drop drastically. my 100W charger would do 30W on port 1 and 10W on port 2. And that was the optimal case - more often than not, using more than one port would make devices randomly disconnect.

It's cheap and there's little responsibility for selling crap. Amazon is the only site I'm aware of where you can actually somewhat judge the quality of a product through reviews, and those too are often dodgy as hell. Otherwise it's all just the same fake pictures and outright lies about specs. And nobody cares because it's cheap.

Companies selling under brands want a premium for them (Anker, Aukey) and "no name brands" you can actually put a little confidence into (Ugreen, Blitzwolf) are, for some reason, rare.

That isn't so surprising nor uncommon even among high-end chargers. Many multiple-port chargers can only generate one voltage other than 5V.

So, you charge your laptop at 100W means 20V*5A, then connect a phone that can only negotiate to 9V. Now your laptop can, at best, only get 45W. But laptop and phone might also have to share the same 5A, meaning something close to what you described. (or, your laptop might not support 9V ... in which case I'd guess one of the devices would disconnect?)

You might be better off using a USB-A port if the charger has one, then your laptop could perhaps remain at ~100W and your phone might still get ~10W. (Assuming charger and phone doesn't also have quickcharge which might complicate it further). Or, perhaps charge your phone via your laptop (yes, negates the point of a multiple-port charger, but if you are in hurry - otherwise, slow charging is preferably anyway)

A good review will test this, and a good product page will specify this (but if your are not looking/thinking about it it is easy to miss).

Be happy the wattage dropped. When I connected 2 fast charging devices my charger just fried.

I just had a 4-port USB brick burst into flame. It certainly would have burned down the house if I had not happened to be in the room. It had sat untouched for an hour before the event.

Wow, what brand?

These brands are like the ship of Theseus - you'll never get the same thing twice.

Better than the brand is the picture of the device (before fire, hopefully) as all the yumcha brands off of Alibaba will usually keep the exact same physical characteristics.

I think you might be unlucky or buying low-quality models. I have a 100W Minix NEO P2 that was one of the first GaN chargers available near me and it's still going strong 2 years later.

I also have a 60W Satechi travel charger that's been powered-on 24/7 for 3 years now without the slightest hint of a problem. It's even been buried under cushions for hours at a time.

The only charger I've had actually die was a Hama-branded device. Hama is the cheapest possible Chinese junk the brand can find.

What brands have you used? My Apple 96W USB-C charger is still doing fine after having it for just under two years now.

Apple cares about its brand. Chinese no name vendors don't at all, it's horrifying what plain illegal corner-cutting they often engage in. But that's of course what they're rewarded for.

In fact, if you're in a bind and need a USB C charger that will work reliably, you may want to pay the cost to get a genuine Apple one. (I won't order Apple chargers from Amazon; I get them direct from Apple or a real retailer because I don't trust the co-mingling).

Some of the power-tool brands are beginning to make USB-C devices, those chargers should be reliable also. Here's Dewalt: https://www.dewalt.com/product/dcb094k/usb-charging-kit

If you bought the device off Amazon, I believe Amazon should be your point of contact for warranty claims.

I have had a couple of pretty cheap high wattage USB bricks for years (5-6 or so at this point) and none of them have died on me so far. Props to Ugreen, I guess!

I have an Anker GAN power block that's working extremely well.

My two Minix P2s had no issues over 1.5 years.

> this 250W unit is 170x50x25

They’ve been selling a 400W (still fanless!) DC-DC version for years and it’s only 160x51.5x26mm : https://hdplex.com/hdplex-400w-hi-fi-dc-atx-power-supply-16v...

I use it to power my CPU+mobo but I also have a couple of server PSUs further away to power my 3090 over several pairs of THNN. It’s far from a SFF build, but it can be totally silent.

The difference is that this unit does the AC-DC conversion inside itself, whereas your DC-DC power supply relies on an external AC-DC brick that is likely the same size as this entire self contained unit, if not larger.

If you're dealing with solar or a vehicle you may already have DC available; too bad it can't take -48v which some racks still supply.

To be a fair comparison would need to include the AC-DC power supply that you keep outside to power that thing... it's double the size once you account for that.

More like 3x. My Emerson 7001484-J000 PSUs go full depth into a server chassis. But that’s a sunk cost since it’s much easier to build a 12VDC UPS instead of a 120/240VAC UPS

I my complaint that they are calling this atx, when the only thing remotely ATX about it is being designed to work with the atx motherboard power connector.

This in no way meets the atx form factor for power supplies, neither the original, nor the 12V version. Like I could forgive it if it failed to be a rectangular prism in favor of having more open space, as long as it had a frame with proper mounting points.

And I could also forgive it if they went with the rectangle, but far shorter than the official 140mm depth (that has always been mandatory per intel specs), given that the market already accommodates non-conforming lengths, and this could be made to not require the bottom of case mounting holes, allowing for absurdly short lengths.

But the photos show none of that, and just a fully custom form factor, without any apparent mounting mechanism.

The form factor and mounting design of the power supply are not parts of the ATX spec. The pin layout & shape, voltages, signaling, etc are what are specified.

This is an ATX power supply. It is just designed for very small cases that would never be able to accommodate the existing standard configurations.

>The form factor and mounting design of the power supply are not parts of the ATX spec. The pin layout & shape, voltages, signaling, etc are what are specified.

Did you just pull this out of nowhere?

Look at ATX Specification v. 2.01 section 4.1, page 18-20. It specifies the "required overall dimensions and general form factor of an ATX power supply," with or without special airflow ducting (emphasis in original).

The linked PSU in the OP clearly does not meet this form factor.

ATX 2.2 spec seems to no longer have that; at least, the PDF linked from the Wikipedia article on ATX doesn't.

Perhaps they removed it in a revision? That seems like a silly idea…

That's a very outdated spec. The size requirements were removed in the current spec.

This actually looks like a server psu.

> (Hoping USB-PD, with it's bump from 20 up to 48V, once again proves another huge win!)

Can someone explain to me why 48V? Is there something special with 48V or beyond? The reason I ask is because some cars now have electric turbos and the manufacturer had to switch to a 48V system. Just curious what the benefits of higher voltage is and if 48 is somehow special.

Thanks in advance.

Power is the product of current and voltage. To transfer much power at a low voltage requires a large current. Supporting a large current without getting hot and melting requires large-diameter wire. Other components may also be bulky or expensive if they have high current-handling requirements.

I seem to recall that somewhere around 50 volts is a magic number from a safety/regulatory perspective. It might also have something to do with semiconductor breakdown voltage, but maybe I'm out of date on that.

My understanding is that 50V is the established threshold above which safety to humans starts to be a factor. So, applications that want high powers, without the penalty of large wires nor the penalty of the safety requirements of an HV system, converge to 48.

> the established threshold above which safety to humans starts to be a factor

Specifically, 50 volts is approximately the threshold above which electricity can pass through the skin and shock you. Lower voltages will only shock humans if they have a way to bypass some of the skin, like wounds or tight-fitting metal jewelry. Otherwise, the resistance of skin is high enough to prevent the flow of electricity. That's why you can touch both terminals of a 12V car battery at the same time and almost certainly not be shocked.

At 48v you can use much smaller gauge wire than at 12v. Which means lower cost, less weight and a smaller footprint for your wire harnesses.

One of the things that can “get you” with these higher voltage systems is you can’t use them to jumpstart the present majority of cars. While I’ve yet to actually see a higher voltage car, I would hope they’d put warnings by the battery to remind the user that “hey, don’t try to jumpstart your friends car with this battery!”

Reply on news.ycombinator.com