Apparently Connected Advanced USB Charger Survey

[Gallymimus]

Hey, potentially interesting device if implemented correctly. I would not mind buying one or two.

I may have a few question (I've quickly gone through the thread, but didn't managed to find the info):

• What kind of power input is needed? 12V, 19V, 12 to 24V? If 19V, then that's interesting since you can use a notebook charger (assuming the plug works), and the 12V could be nice for car usage.
• BTW, do you intend providing a primary PSU bundled in the package? It would nice to be able to buy the kit or just the charger.
• Any chance for an extra "direct" 5V output on a better connector for power distribution (I would like to suggest a PowerPole, but that could get me lynched on some forums), with adjustable current limit?
• Any plans for a travel version with maybe two outputs and a smaller primary PSU?

Thank you and best regards,
Dan

10V to 28V should work fine.  The only limitation is that the general 2.5mm x 5.5 mm Barrel plug we currently have on the design can only handle 5A so that would limit your total power output at the low end of the voltage input.  I've not found a higher current easy to implement barrel jack that can handle more current yet. 

We did envision using standard 19V laptop bricks!  The only issue is getting the physical connector adapters.  As you know they vary a bit between notebook brands.

To get full power with the current prototype (all ports at 3A) you probably want to stay above 18V input)

[Balaur]

10V to 28V should work fine.  The only limitation is that the general 2.5mm x 5.5 mm Barrel plug we currently have on the design can only handle 5A so that would limit your total power output at the low end of the voltage input.  I've not found a higher current easy to implement barrel jack that can handle more current yet. 

Hello and thank you for your answers. Much appreciated.

Yay, hooray for 5.5mm jacks. Very reasonable practical choice (assuming high quality plugs and connectors). Thought you'll end up dissipating around 0.75 W though (30 mohms contact resistance) @ 5 Amps enough to shave 1.25% of your efficiency (@ 60W). In any case, this will be dwarfed by PSU to charger cables resistance.

Overall, yep, better use a higher input voltage.

[Gallymimus]

10V to 28V should work fine.  The only limitation is that the general 2.5mm x 5.5 mm Barrel plug we currently have on the design can only handle 5A so that would limit your total power output at the low end of the voltage input.  I've not found a higher current easy to implement barrel jack that can handle more current yet. 

Hello and thank you for your answers. Much appreciated.

Yay, hooray for 5.5mm jacks. Very reasonable practical choice (assuming high quality plugs and connectors). Thought you'll end up dissipating around 0.75 W though (30 mohms contact resistance) @ 5 Amps enough to shave 1.25% of your efficiency (@ 60W). In any case, this will be dwarfed by PSU to charger cables resistance.

Overall, yep, better use a higher input voltage.

This product definitely isn't an efficiency play .  It's really focused on quality of power and precision regulation.  For an efficiency play we'd have used a different approach and no secondary LDOs.

Glad you like the charger!  It should be pretty neat once we get it all done!

[Richard Crowley]

No, there is no need for something like this. But there is no need for a Cadillac Escalade pick-up truck, either.  And you can probably buy a gold-plated toilet plunger at some rich-person's boutique, also.  This gadget is well into "audiophool" product space.  The passion and engineering and execution are admirable. But they should have selected a non-trivial product to make.

[Gallymimus]

No, there is no need for something like this. But there is no need for a Cadillac Escalade pick-up truck, either.  And you can probably buy a gold-plated toilet plunger at some rich-person's boutique, also.  This gadget is well into "audiophool" product space.  The passion and engineering and execution are admirable. But they should have selected a non-trivial product to make.

As we've said many times, it is a niche market.  Niche markets are more interesting from a business and engineering standpoint IMHO.  We have no interest in making a "trivial" device that has 5 components and competes with low quality Chinese manufacturing.  That doesn't deliver anything new or much value.

That's why we went for a "non-trivial" and rather complex design that offers more, and delivers more, in an aesthetically pleasing and high quality fashion.  Many people want the best, that's what we are bringing to market.   Certainly people can use something cheap from China, or that came with their phone instead.  People who want the best, the most information, and the highest quality, and greatest convenience may appreciate what we have designed. 

[Richard Crowley]

Please  note, I did not characterize your product design as "trivial", it obviously is quite elegant.
But the APPLICATION (USB charger) is trivial and does not demand elegance where simple competence is required.
The fact that there are low-quality products out there is not an argument that the market demands premium products.
But it is a free market and you can design and sell whatever people will buy.
Perhaps it is a good starter project to allow sinking your teeth into something substantial next time.

[Gallymimus]

Is there an actual need for that though? I have never had trouble charging stuff on USB, and all USB devices are designed to accept fairly dirty, poorly regulated power because the spec says they must. What problem are you actually trying to solve?

You'd be surprised.  It's a situation where we don't have enough information about our charging to really know how things are proceeding.  We've seen a lot of chargers produce very low voltages (close to 4V) and also seen a lot of chargers, when mismatched with the device being charged, produce very low currents, 400mA in some cases.  When you device is capable of charging at 1A or 1.5A this kinda sucks and you don't really know since most of us don't time our charging.  So it's definitely offering charging peace of mind, and I like data personally so it's cool to know exactly how the charging is progressing. 

If I can be sure my device is charging in 3 hours instead of 5.  I want to take advantage of that if I can.

[nathancrum]

I understand the sentiment that USB charging is a trivial task, but we don't feel that's really true for 2 main reasons:

1) USB charged devices are pervasive and becoming more so.  Although there are certainly chargers available; most are not multi-port, most are not >2.0A capable, most provide very noisy power and almost all are not universally compatible.  To anyone with a "high-power" USB device (or several), those are all real problems that all together - require a complex solution.

2) I care about quality.  Especially when a lack of quality could mean poor charging performance or at worst - either damage my expensive toys or burn down my house.  All of these "commodity" electronics are in a race to the bottom for price and they suffer because of it.  Not everyone will care about the differences, but we do - and we're hoping others will too.

We too entered into this design with little appreciation for how difficult it is to perform what seems like such a simple task and perform it well, but we know now that this is a non-trivial challenge and it requires a non-trivial solution.  Is it over-the-top?  Sure, but so is a $700 smart phone. 

[Richard Crowley]

Now if there were a USB charger that could query the gadget to identify what it is, that would be great.
Then if it had (or could develop over time) a charging profile to sense the instantaneous, as well as the delta current, and could accurately predict the state of charge and the time to "full". That would be a great thing.  Sony does this with camcorder batteries for my video cameras.

Even better would be to champion some common protocol where the charger could query the gadget about the state of the battery charge, the discharge profile, the number of charge cycles, etc. etc.  That would marvelous.  You could be in the forefront of truly "professional grade" chargers for USB devices.

[Balaur]

I still see value in a good quality USB charging solution.
Providing 5V@2A sounds trivial, but when you look at the vast majority of the products out there, you realize that's not easy to find one that works as nicely as you thought.

I have a rather large collection of load profiles measured with my trusty West Mountain Radio CBA. Many 5V chargers have a drop of a few hundreds of mV under load, even nice ones (example: - the ASUS delivered with my Nexus 7 has some 237 mV drop @ 2A), while others try to compensate for cable loss (the Samsung Nexus 10 one has +200mV@2A). BTW, this is the voltage seen at the USB output connector.

I've bought a Nexus 10 MagNector (magnetic connector) and when coupled to a good 5V source and cables, it's able to charge the battery much more predictably and some 10-20% faster that the best USB charging combination I've managed.

Without any particular precautions, 1-1.5A loads make the end voltage (i.e. at the end of the USB cable) to reach 4~4.5V, which may not enough to allow battery charging at full speed. In practice, the device and the charger will reach a difficult-to-predict balance between the drawn current and the voltage loss.

[nathancrum]

Personally I'd like to see a charger that puts out LESS power on request. Like a switch that drops it down to 500mA. I usually charge my phone overnight so it doesn't matter if it takes longer. By charging slowly the battery is preserved and less waste heat is generated. Constant fast charging reduces battery life, and particularly on Apple products where the battery is not user serviceable that is a big concern.

That's a great idea - "battery saver" charge mode.  That's certainly something we can implement with our existing hardware.  I agree - I'd much rather my phone trickle charged overnight - it's got a full 8+ hours, it might as well charge the batteries gently when I have enough time.

[corrado33]

The problem I have with the device is this. When are you going to use it? It has to be plugged in so it's not entirely "portable." Not to mention that it requires an external power supply? Terrible idea. No one wants to drag along ANOTHER power supply when they're on the road. The high power delivered is conducive to fast charging, so one would assume that a person would want to use it when on the road, say at an airport or similar. But, in that case, would it not make sense to have a simple battery powered solution? NiCds can supply a heck of a lot of current. Fast charging of any type of battery shortens it's life (you can argue this point either way).

The "fastest" type of charging say at an airport would be simply to buy some batteries and slowly charge your phone while you're on the plane. Buying (always available) batteries is quicker than waiting for your phone to charge. Heck, I'd feel better if the product WAS a rechargeable battery capable of being quickly charged. You could then charge your phone with it. (Many of these products exist already.)

If the target useage area is in the home or office, then what's the point of charging the device quickly?

Yes, I'm entirely ignoring the whole "clean power" thing. It's a charger, it doesn't need super extra awesome clean power. You don't want to compare yourself with monster cables. That won't win you points on any forum that has semi-educated members.

As mentioned before, I feel this device falls into the "audiophoolery" market. (Trying to prove that power supply noise has an effect on the audio something or other (in a phone).  )So you've made a product to sell to...ignorant, rich people. (Most rich people I know are educated enough to see through the marketing for this.) Not the best business plan unless you're making these things quickly enough and cheaply enough to change it up to draw in more people (see any major chinese company that does the same thing.)

I admire the craftsmanship, but in the end there is no market for this device. That's my opinion at least.

[PlainName]

When are you going to use it?

I have no interest in this project, but just to mention...

On my desk I have a pad and phone, and I got fed up of plugging them into the PC to charge and take up a drive reference (screws up my auto-backup to external drive). Plus they don't charge that fast, and if you set them to charge only then you have to dick about to get them to connect for syncing.

So, I have the charger for the pad plugged into a socket and plug the pad or phone into that whenever they want charging. Each is set to be a disk on connect, but since they're not connecting that's not a problem any more.

This sort of project would be great for my needs since I am at my desk more often than I'm not (but I am happy with the pad charger, so don't need it). Whilst I accept that everyone has their own preferences, there are just too many people for me to be alone in this.

[corrado33]

When are you going to use it?

I have no interest in this project, but just to mention...

But why buy THIS product, over the multitudes of much cheaper ones on amazon? You simply want a distributed USB charger, which can be found a dime a dozen.

The small form factor of this product makes it look like they're targeting a traveling audience. Have you ever tried to use a tiny travel USB hub on a desktop? It's a PITA, it always moves around.

Besides, your system is overly complicated. Why not simply charge them both via the wall then only plug them into the computer when you want to sync? (This essentially is exactly what you'd be doing with a product like this.) You seem like a pretty computer literate person, so why not write a script that deals with the drive referencing?

Everyone knows devices charge slowly when connected to a computer instead of to it's dedicated charger.

[PlainName]

But why buy THIS product

Er... well, I'm not. But if I were looking for something, if this is obviously well made and has a good spec, why not? Cheapest price isn't necessarily the overriding factor if you want quality, you know.

your system is overly complicated

It is? Not sure how it could be simpler, but perhaps I didn't explain it very well (there isn't much to explain really).

Why not simply charge them both via the wall

That's what I am doing! Except I use one charger, and this particular charger because it fits in a switched multiway adapter unobtrusively, and can bung out serious amps to fast charge the pad.

I never thought that was complicated!

so why not write a script that deals with the drive referencing

Good lord, no! Once I'm down that route there would be no end to what I might feel like doing

The problem is simple yet without a simple resolution (that I know of). Windows gives a newly plugged in drive the next available reference, which on my system happens to be O:. So I plug in my backup drive and it gets O:, except for the other backup drive which gets P: sometimes. My backup software will thus look at O: and P: for these particular drives.

If I have the phone plugged in it take up O:. Except if it's plugged in before Windows has booted, in which case it takes up L:, my first mapped network drive, and then my accounts won't work because the account data is on L:, which is no longer the network but the phone. But at least the backup would work!

If you think a script is easy to write to cope with all this, be my guest in writing it - I would no doubt be enormously grateful 

Everyone knows devices charge slowly when connected to a computer

Do they? A techy might, but your average phone abuser might not. Even if they did, sometimes slow isn't a problem: if you get into work, say, and plug your phone in whilst you're there, it matters little if it takes half an hour or several hours so long as it's done before you go home. And, you have to admit, a USB slot in your PC is often much simpler to plug into that a wallwart over the other side of the room.