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Comment by pdelbarba | Hacker News Reader

I've had a ton of issues with USB power supplies and cables not allowing devices to charge properly (Improper wiring, termination, fake specs, etc) and so I started testing everything I got using a USB power meter and test load. Anker is the only brand on Amazon that Ive found to reliably meet spec. Their newer USB battery packs in particular are very interesting because they will ignore the line termination and do a TCP-like ramp on amperage until they get a voltage sag, then pull back slightly and sit there. This is especially entertaining because they'll melt really poorly designed USB supplies :)

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This is why Anker is successful imho. Not because they offer a better battery / charger / cable. But because they free users from having the think about it.

Most people don't want to have to think about USB power delivery handshakes and resistors. And they don't want to research what they need to look for in a USB 3.0 cable vs that USB 2.0 cable they bought years ago.

Anker seems to be technologically on the ball, but above and beyond that it's a "we promise not to @$^# up the accessory we sell to you" guarantee. Which the Chinese fly-by-nights seem incapable of grasping.

In other words, they've cultivated a brand of trust through their product lineup (what they offer vs what they don't offer), product design, and packaging design.

I have their 6-port USB charger in the mudroom of the house. We plug in our phones, tablets and bike lights upon entry. Excellent performance, and yes, I never have to think about it. It just works (at US and Euro line voltage).

I did find the packaging a bit ostentatious for a USB charger. A plain corrugated cardboard box would have been more appropriate for mail-order, though I can see why they might want to "steve-job" the packaging for retail.

What's a mudroom?

> Many suburban American houses have a mud room, a casual, generally secondary entryway intended as an area to remove and store footwear, outerwear, and wet clothing before entering the main house. As well as providing storage space, a mud room serves to increase the cleanliness of a house proper.

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

A foyer for the back door. Usually you'll have a tile floor and rougher walls.

You do messy stuff there, like take off your winter boots, or leave your bike.

A (usually back) foyer where you take off/store your muddy shoes.

(It's common in farm houses where it's typical to be out in the muddy fields. Most of America by geographical land area is farm land.)

> Most of America by geographical land area is farm land.

No, total agricultural land is less than 1 billion of a total of 2.3 billion acres.

That's certainly why I do it.

Getting Anker products is so much easier and quicker than the old way of trawling through pagefuls of cables trying to find those that appeared spec compliant (thanks, Benson!), reasonable quality, and don't try any scams like "Fully USB 3.1 compatible" thanks to USB 2.0 fallback.

"Their newer USB battery packs in particular are very interesting because they will ignore the line termination and do a TCP-like ramp on amperage until they get a voltage sag"

This comment doesn't make sense in the context of the battery pack being used as a charger. Are you talking about when the battery pack is charging?

yes, they have to be because they said "This is especially entertaining because they'll melt really poorly designed USB supplies :)"

I read this as "some devices don't correctly signal what amperage they want, so the anker pack ramps up until it detects some change that indicates the device is charging at full speed."

I'm referring to the charge rate of the packs themselves. Amperage doesn't work the same way voltage does. You could hook your phone up to a 1000 amp supply as long as it's 5V so there's no point in starting lower and ramping up the output since the device will only use what it can take.

(for clarification, the principle is V=IR, you could hook a 5V incandescent lightbulb or LED up to that same 1000A supply and it would only draw I=V/R (Current = 5v / series resistance). Yes, there is silicon controlling the battery, but at the most basic level, if the series resistance of all that plus the battery is 5 ohms, it will only draw 1A)

Edit: math fail

The charger could push more current by increasing the voltage, but that would be dangerous and most likely damage the device--unless the charger could somehow sense the resistance of the charging cable and compensate for the voltage drop, then the output would be >5V at the charger, but =5V at the end of the cable. That would take some sorcery I'm not aware of though.

LEDs use constant current power supplies with variable voltage, and I've seen some hybrid designs with exotic combinations of constant current / constant voltage regulation.

It's incorrect to think of the charger as "pushing" current. Not only in general electrical theory, but also in the context of charging lithium ion batteries. The real 'decision' as to how much current is used is in the management IC for the battery, which converts the 5V from the 'charger' to a variable voltage and current based on the charge state of the battery and its input power specification.

See, for example, this design note from Linear Tech: [0] which describes a 20V adapter, analogous to OP's 5V USB 'charger', that can provide 2A (40W total) to the laptop. If the laptop battery charge management IC says that the battery can use up to 2.2A at 12.6V = 27.7 W, but the laptop computer is using more than 40-27.7=12.3W, it will reduce the charge current to the battery to avoid damaging the 20V 2A adapter. The problem that pdelbarba's USB battery packs are solving is that they can be plugged into various adapters - perhaps a port on a laptop limited to 500 mA, or a 1A 'phone charger' or a 2.1A 'tablet charger'. Some manufacturers solve this by adding resistors to their chargers so that the device can sense the resistance and know it can use up to 0.5, 1, or 2.1A. But everyone uses different resistors.

So Anker does a functional test rather than the electrical equivalent of user-agent-string parsing to set the current limit.

> unless the charger could somehow sense the resistance of the charging cable and compensate for the voltage drop, then the output would be >5V at the charger, but =5V at the end of the cable. That would take some sorcery I'm not aware of though.

That's pretty standard for lab power supplies. It also is used in precision metrology with sensors like load cells. All it takes is a pair of non-current-carrying wires to sense the voltage at the device. The current-carrying wires experience a voltage drop, but the sense wires are only feeding into high-impedance measurement inputs. This is known as a Kelvin connection.[1] With a device that takes an excitation voltage, you'd use a 6-wire connection.[2]

[0] http://cds.linear.com/docs/en/design-note/dn194f.pdf

[1] https://en.wikipedia.org/wiki/Four-terminal_sensing

[2] http://loadcelltheory.com/LoadCellSupportTheoryPDF/ShuntCalR...

Thanks for detailed reply with references. Knowledge enhanced. :)

Yes, I suppose it's incorrect to think of the charger as pushing current; but with a resistive load, with LEDs, with raw lithium cells, most batteries, and with most loads in general, the current can be expected to increase as the voltage increases. And some power supplies regulate output by current rather than voltage. I didn't know that about lab power supplies, very interesting!

Awesome writeup! Another thing that I should probably have mentioned earlier is that the resistors are across D+ and D-, allowing the device to know that it's A) not plugged into anything it should be talking to and B) what the output of the charger is. This get's really entertaining when you start talking about USB C where if the resistor is used incorrectly, you can start doing real damage to device and charger.

Yep, HP / Agilent supplies typically have the sense connections, and they're useful for compensation from various factors :)

My friend was going scuba diving on an island without power. He bought and tested 5 different brands on Amazon. Anker was the best. He had an extra battery, so I bought it from it. It was worked wonders when I am traveling for the day and need to charge my phone.

Is this you?

https://arstechnica.com/gadgets/2015/11/google-engineer-leav...

Can you recommend a portable USB charger of there's? I sold my wife on getting one when she needed to replace her's because of their solid reputation, only to have it break three months later.

Maybe the typical one would have broken down after couple of hours?

How did it fail? I have a few of the PowerCore chargers and have had no issues.

It stopped charging fully and would no longer power any devices. I just tested it the other day while I was getting ready to recycle some other electronics and it was still doing the same thing.

Did you contact Anker? Among the many products I've bought from them, I've had a couple of problematic ones, but have found that in these cases their support has been very helpful and sent me a replacement, even a year or so after the original purchase.

No, but I should have. It broke during a trip out of the country and we needed to replace it then and there. Thankfully, we were in Japan, so we had no shortage of options. I'll keep that in mind if I buy from them again.

You can buy any of theirs that was manufactured in the last 1.5-2 years and you shouldn't have a problem. I wouldn't buy one that was originally made 3-4 years ago just because the cells might have lost a lot of capacity. Like the others said, if you contact them they have great customer support and will often (very anecdotal) send you a free one.

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