Apparently Connected Advanced USB Charger Survey

[Gallymimus]

Our friends have a Kickstarter for a new high tech USB mobile device charger launching soon (next few months).  We need some feedback from YOU on the device.  There is gift card giveaway (might only be useful in the US though) if you participate as a small thanks for your time on the survey!  Thanks for the help.

Go to Survey HERE---->         http://svy.mk/1gyMyc9

[minibutmany]

It is unclear, does this unit have a battery in it? Or does it connect to AC power to charge the devices?

[Gallymimus]

This would be a line powered device (to be exact using a power brick located elsewhere).  It's a high power charger so there wasn't a better way to keep it sleek without bulking up.

[nathancrum]

It's meant to look anodized red, not pink - not that there's anything wrong with pink.     It will also be available in black, blue and clear to start with - push goals could open up more color choices.

Regarding advantages compared to the average multi-port charger available:

• Every port has a full 3.0A of charging capacity (simultaneously - 60W total)
• Every port has a dedicated microprocessor trimmed LDO regulator
• The input power is regulated to just above the LDO dropout using a multi-phase buck converter for low noise and higher LDO efficiency
• Together this results in very good voltage accuracy and extremely low output noise (nearly zero transient voltages even without a load)
• Every port is monitored for current and voltage - providing live feedback, charging status and current limiting
• Every port has a dedicated charge protocol controller providing true universal high-speed charging for all devices (Apple, Samsung, etc.)
• It's housed in a billet machined enclosure - some people may like that, some may not, but it's durable and I think sexy looking.

That's most of the highlights anyway.  It's not a cure for cancer - it's just meant to be a very high quality charger.

[Zbig]

I stopped reading after "The most advanced USB charger ever made" and "most sophisticated high-power, 4 port USB charger on the planet". Slogans like this make me wanna cry. Or puke. No, wait, make that both.

[Gallymimus]

I stopped reading after "The most advanced USB charger ever made" and "most sophisticated high-power, 4 port USB charger on the planet". Slogans like this make me wanna cry. Or puke. No, wait, make that both.

Fair comment,  What would you say to earn credibility if you believed you had something better than what was on the market?  What kind of phrasing would appeal to you or convince you?

[Rerouter]

That comes down a bit to how you have tested it, if you actually designed it with parts quality in mind saying things like "Built with quality and robustness in mind to make the most flexible high current charger on the market" or similar while still marketing, it doesn't exactly shun the engineer type guys away by sheer buzzwords

(claiming something is the most advanced implementation of what is generally a simple device is what turns them away)

[nathancrum]

I stopped reading after "The most advanced USB charger ever made" and "most sophisticated high-power, 4 port USB charger on the planet". Slogans like this make me wanna cry. Or puke. No, wait, make that both.

I understand what you mean.  We're definitely not marketing guru's and could probably benefit from tempering the wording to sound more credible, but we don't think those are outrageous claims either.  There are only a couple chargers anywhere on the market with similar quality and sophistication (for use with very high end DAC's), but they're not multi-port and they're not really intended to charge anything - they're for directly powering sensitive audio equipment. 

We've taken a traditionally simple and cheap product and engineered the hell out of it and that's a value proposition we're still trying to figure out how to craft for a wide audience - both tech/engineers and average consumers.  You're probably right though - buzz words are probably more universally harmful than helpful.  I don't know of a simple way to sum up everything we've designed into this charger without a few of them though - will have to hit the thesaurus and get creative.

Thanks

[Richard Crowley]

So all of those claims may be true. But what difference does it actually make to have "low noise and higher LDO efficiency" or "very good voltage accuracy and extremely low output noise"?
If I am only charging a device (or even POWERING a device, for that matter) why should any of this actually matter to the customer? Why would it be to my advantage to have a "premium" USB charger?  Why would I buy a gold (or even gold-plated) screwdriver? 

A charger is a low-end utility item that does not require "precision", but only "competence". You would have to convince us why "precision" is of any practical value to the end-user?

I recently bought one of these gadgets at my local cable shop for US$38 and it doesn't need a wall-wart.  Brilliant:

[Gallymimus]

That comes down a bit to how you have tested it, if you actually designed it with parts quality in mind saying things like "Built with quality and robustness in mind to make the most flexible high current charger on the market" or similar while still marketing, it doesn't exactly shun the engineer type guys away by sheer buzzwords

(claiming something is the most advanced implementation of what is generally a simple device is what turns them away)

Thanks for the comment.  You are certainly right.  We'll look at that approach when we put together the final marketing package.  It's always hard to pick the marketing tone depending on who the audience is.  With a new product we don't know who the audience will be.  I suspect it won't be so many of the engineers but more of the sky mall and sharper image crowd.

[Gallymimus]

So all of those claims may be true. But what difference does it actually make to have "low noise and higher LDO efficiency" or "very good voltage accuracy and extremely low output noise"?
If I am only charging a device (or even POWERING a device, for that matter) why should any of this actually matter to the customer? Why would it be to my advantage to have a "premium" USB charger?  Why would I buy a gold (or even gold-plated) screwdriver? 

A charger is a low-end utility item that does not require "precision", but only "competence". You would have to convince us why "precision" is of any practical value to the end-user?

I recently bought one of these gadgets at my local cable shop for US$38 and it doesn't need a wall-wart.  Brilliant:

Again good comment.  So we've thought about this and you are right.  How do you convey value.  As an engineer I'm with you.  A very weak argument is products like Monster cable and motherboards which claim solid capacitors and multiphase converters are certainly questionable from an engineering standpoint yet they do quite well on the market (I think!). 

We are still doing some testing but one of the areas where the precision and low noise has benefit is in the audio space.  You may have seen that there is a community of audiophiles who buy USB DACs and want clean power for those devices.  We're looking into whether the phones have lower audible noise with the precision voltage regulation.

Another thing that isn't often included in the chargers like the one you highlighted is they often can supply 8A max, but really can't negotiate the 2 or 2.5A charge current to the higher end tablets or other apple devices.  If you happen to have tried measuring on yours it would be a great data point.  Typically they really supply about 1 to 1.5A because the D+ and D- pins are simply shorted together in the charger (which corresponds to the standard USB dedicated charging port spec).

it's in the same vein of buying a Lexus vs a Toyota.  There are some niceties, features, and levels of quality that are far beyond the basic options.  Is this worth it?  Well some consumers say heck yeah and many don't.

Really appreciate the discussion.  We of course want to put the best foot forward on the product and have the greatest appeal for it even though it will never capture EVERYONE's interest.

[tom66]

I really doubt the average phone is designed for low-noise audio. You've got a 3W radio drawing power from the same source now and then and within 10cm of the audio electronics. It doesn't matter how clean your input power supply is if that happens to transmit.  Not to mention the typically cheap DAC that is used because cost > some audiophile nonsense.

Presumingly you're running off a 12V(?) plugpack with whoever knows what type of crappy flyback it in spitting emi everywhere, make sure to test that.

Make sure the desired PSRR LDO @ frequency of your switcher exceeds that of a better designed high frequency switcher...

[mariush]

Every port has a full 3.0A of charging capacity (simultaneously - 60W total)

which would be pointless if you don't controller the data lines to simulate various standards (there are ICs that detect the device and "talk" to device and enable high current)

Every port has a dedicated microprocessor trimmed LDO regulator
The input power is regulated to just above the LDO dropout using a multi-phase buck converter for low noise and higher LDO efficiency
Together this results in very good voltage accuracy and extremely low output noise (nearly zero transient voltages even without a load)

Which is pointless... by definition the usb voltage is 5v +/- 5% or something like that, so devices MUST be tolerant of variations in voltage, must consider the cable length causing some voltage drop etc etc...

• Every port has a dedicated charge protocol controller providing true universal high-speed charging for all devices (Apple, Samsung, etc.)

now you mention it...

[zapta]

I recently bought one of these gadgets at my local cable shop for US$38 and it doesn't need a wall-wart.  Brilliant:

Looks nice, what model?

As for the OP, you started the price choices at $50. You should have lower prices, don't assume other people value it as you are.

Edit: I am using this $5 device to debug charging speed.  http://www.apparentlyconnected.com/wp-content/uploads/2013/12/Idea-03.09.jpg  You plug charger and cables until you get a good reading (e.g. >1A for a phone).

[nathancrum]

We really appreciate the feedback, but I don't want to get too side-tracked on the quality issue.  The fact is - we need to collect a lot more data and even with a mountain of it - making definitive statements about what someone *needs* with regard to voltage stability, accuracy and precision is going to be almost impossible.  That said - we do think noise matters and there are tangible differences.  Attached are samples of a 60 Hz audio tone from a smartphone on battery power vs. on a poor quality charger (I haven't had the chance to test on our circuitry yet).  Can your device operate with low quality power?  Certainly - many millions do every day.  Do you want to submit your $700 smart phone or tablet to poor quality power every day if there's an alternative?  That's up to you.

There are a few significant advantages to our charger that are not subjective though too:

• 3.0A on every port is unique.  Most multi-port chargers provide only one high power port and/or 2.1A is the most common maximum currently.  It's highly probable that max will get increased again as manufacturers chase ever faster charging batteries and more power hungry devices.
• Automatic protocol negotiation for high power charging is extremely rare.  Most chargers support only one device family (there are at least 3 major families: Apple, Samsung and pretty much everything else).  If your device is incompatible - it will charge at reduced rate (500mA).
• Feedback.  Most chargers provide none.  Ours provides color-coded LED status indicators on each port.  We have not yet explored all the ways this can be used, but we expect to be able to show when a device is nearly finished charging, when it's done, just started, etc.  The original post was asking if there was any perceived advantage to adding an OLED screen for more feedback (power drawn, time charged, voltage, etc.)
• Current and voltage monitoring.  Besides being able to trim voltage for accuracy, our charger also has the capability to 'watchdog' the output and cut it if something goes wrong with the host device and it starts drawing too much current.

Again - we appreciate the feedback - please keep it coming.  Let's try not to get too bogged down in whether you view quality as worthwhile.  Some people buy cheap components and expect to have them fail or be inferior.  Others want quality and craftsmanship and of course there's also every shade in between.  We're trying to appeal towards the later end of the spectrum - admittedly - without urgent, demonstrated need.  I know for ourselves at least - we wanted to push back the race-to-the-bottom and build a better product - one that might actually last awhile, one that performs well and one that looks good on our desk.  Hopefully we're not alone in those desires.

[zapta]

Automatic protocol negotiation for high power charging is extremely rare.  Most chargers support only one device family (there are at least 3 major families: Apple, Samsung and pretty much everything else).  If your device is incompatible - it will charge at reduced rate (500mA).

That's a very good feature and can be a strong selling point. Does it mean that regardless of the USB cable configuration and the device type your charger will be detected as AC rather than USB?

As for the audio of the ripple, that's reminds me late nigh informercials. I wouldn't take it seriously.

[Gallymimus]

I really doubt the average phone is designed for low-noise audio. You've got a 3W radio drawing power from the same source now and then and within 10cm of the audio electronics. It doesn't matter how clean your input power supply is if that happens to transmit.  Not to mention the typically cheap DAC that is used because cost > some audiophile nonsense.

Presumingly you're running off a 12V(?) plugpack with whoever knows what type of crappy flyback it in spitting emi everywhere, make sure to test that.

Make sure the desired PSRR LDO @ frequency of your switcher exceeds that of a better designed high frequency switcher...

Yep,  you are right.  We've yet to prove that the switching noise from a standard charger (with a few hundred mv of ripple) is audible or not.  We're using a small multiphase converter, LC filters, and the LDO.  So far it's proven to reduce the electrical noise substantially.  The switching noise from the brick (24V actually) doesn't make it through in any significant way.

But yeah, the phones aren't the best audio devices, but if it makes a difference it would be a bullet point. 

[Gallymimus]

Every port has a full 3.0A of charging capacity (simultaneously - 60W total)

which would be pointless if you don't controller the data lines to simulate various standards (there are ICs that detect the device and "talk" to device and enable high current)

Every port has a dedicated microprocessor trimmed LDO regulator
The input power is regulated to just above the LDO dropout using a multi-phase buck converter for low noise and higher LDO efficiency
Together this results in very good voltage accuracy and extremely low output noise (nearly zero transient voltages even without a load)

Which is pointless... by definition the usb voltage is 5v +/- 5% or something like that, so devices MUST be tolerant of variations in voltage, must consider the cable length causing some voltage drop etc etc...

• Every port has a dedicated charge protocol controller providing true universal high-speed charging for all devices (Apple, Samsung, etc.)

now you mention it...

Yep spot on.  Tolerance is actually 10% so it's even worse than you suggest.  This is a premium product and some people care some don't.  In fact one of our planned features is a boost mode which pushes the 5V to 5.5V to improve the charging performance by an additional 10%

[Gallymimus]

Automatic protocol negotiation for high power charging is extremely rare.  Most chargers support only one device family (there are at least 3 major families: Apple, Samsung and pretty much everything else).  If your device is incompatible - it will charge at reduced rate (500mA).

That's a very good feature and can be a strong selling point. Does it mean that regardless of the USB cable configuration and the device type your charger will be detected as AC rather than USB?

As for the audio of the ripple, that's reminds me late nigh informercials. I wouldn't take it seriously.

yes that's correct on the AC vs USB for charging.

I think what will make the audio point truly relevant to regular people is if we provide some audio samples that show a modest audible difference.  That would sell me on it if I were a potential customer.

[rfbroadband]

I assume you guys looked at the thermal design aspects of this when all ports provide the full load of 3A?

[Gallymimus]

I assume you guys looked at the thermal design aspects of this when all ports provide the full load of 3A?

Yes Sir.  One of the things we are doing is adjusting the muliphase converter to be just above the dropout voltage of the LDOs to minimize heat lose.  The multiphase should be about 92% so that's a few watts and the LDOs will each lose about a watt each.  Given the aluminum enclosure heat shouldn't be a problem, though it will get slightly warm to the touch.  Efficiency hopefully won't be a big issue since we aren't talking about "vampire power" and the regulators will be shut down when there isn't a current draw.

This has be a point of skepticism for us when looking at other chargers on the market that claim 8A for instance.  A few watts in a sealed plastic box builds up heat pretty quickly.

Thanks for the comment!

[tom66]

92% efficiency is that real world or datasheet best case?

92% is pretty typical for the mid-point of operation of a switcher, but remember they typically roll off on efficiency as you approach maximum load; 92% sounds more like a mid-loading best case efficiency point.

But if you assume 92% efficiency you need to get rid of 5W in your switcher (not impossible, but challenging) plus 1W per port. Your aluminium widget will dissipate 9W so it will run quite hot.  This heat  will decrease efficiency further (ON-resistance of MOSFET increases with temperature) so make sure to do a full load burn-in test on the final product.

[Gallymimus]

92% efficiency is that real world or datasheet best case?

92% is pretty typical for the mid-point of operation of a switcher, but remember they typically roll off on efficiency as you approach maximum load; 92% sounds more like a mid-loading best case efficiency point.

But if you assume 92% efficiency you need to get rid of 5W in your switcher (not impossible, but challenging) plus 1W per port. Your aluminium widget will dissipate 9W so it will run quite hot.  This heat  will decrease efficiency further (ON-resistance of MOSFET increases with temperature) so make sure to do a full load burn-in test on the final product. 

Great point!  I hope we won't have to use a thermal gap pad material to conduct heat to the aluminum billet but we have that as a fallback if needed.

The switchers we are using approach max efficiency as load increases (losses are primarily switching), also it's a multiphase so the switching/rdson losses are distributed across 4 switches (synchronous dual phase buck), and copper losses are distributed across 2 inductors.

92% was a mid to high load back of napkin calculation based on the other switchers we've done for customers.  It IS going to get a bit warm so we'll see how it ends up!

The datasheet doesn't actually quote efficiencies.  We've got some work to do on tradeoff between component sizes, switching frequency and end efficiency.  As you know there are a lot of competing variables in a switcher design.

You are right, a full burn in test on several prototypes running at a 50C ambient is mandatory to prove out a high quality robust design.  No cutting corners if you don't want to have failures.  I'm no genius and often miss things on the first prototypes.

Thanks for the suggestions, we don't want to miss anything that we don't have to.

[Gallymimus]

Arriving just in time to be made redundant by wireless charging. I haven't plugged my phone into anything for months.

Great point.  certainly wireless charging is a sexy competitor to a physical cable.

Except that wireless charging isn't suitable for many application.  For instance, if you want to charge fast wireless currently isn't suitable.  The current implementation of the Qi charging spec only supports 1A (5W) while were talking about 3 times faster than that.  If I'm in a hurry I don't want to wait 3x longer to get my tablet or phone charged.

I have a Qi charger at my home and use it for my tablet each night.  It's OK, but hardly awesome.  It definitely serves it's purpose and for slow lazy charge overnight I love it.

Which devices / wireless charger are you using?  I find it's a pain to align my tablet over the coil on the charger, maybe you don't have that problem with yours.  Do all of your devices support the wireless charging pad you are using?

USB charging is going to be around for a while, Especially since the new charger spec (USB Power Deliver Spec 1.0 http://www.usb.org/developers/powerdelivery/) will support 12 and 20V and up to 5A.  We will likely see monitors and notebook computers powered via the new USB specs.  Wireless won't be getting there for some time.

[peter.mitchell]

how well does it respond to abuse? (shorted output, shorts between gnd and data, shorts between v+ and data, 12v down the 5v line )

[Gallymimus]

how well does it respond to abuse? (shorted output, shorts between gnd and data, shorts between v+ and data, 12v down the 5v line )

Good question.

It will be very robust against shorted output.  It's not fused but the LDOs on each output have internal current limits at 3A.

Shorts between V+ and data, data to data and data to ground shouldn't present any problems as they should be able to survive up to a diode drop above VCC.

12V down the 5V line is a little tougher and we haven't testing this yet (only have a few prototypes and don't want to start destructive testing yet).  The real point of risk is whether the LDOs can be back fed at that voltage.  Their inherent transistor structure is rated for much higher voltages but the back feed might not play nice. 

We've considered whether putting some transorbs or zeners on the output makes sense.  The down side to this is that in most scenarios they would just burn up if a high voltage (with some current behind it) is placed across the output.  It would give us an indication that the product was abused but it doesn't do a lot for the consumer.

[free_electron]

Do you support PD charging ?

[Gallymimus]

Do you support PD charging ?

I wish .  If we can get this product off the ground we'd definitely like to be one of the early to market suppliers of a USB charger that supports the Power Delivery specification.  I'm not even sure a muliport charger for PD would make sense (at least if you tried to do 4 ports at 100W each you'd have a really hard time keeping any reasonable form factor). 

 

[Harvs]

Totally un-related to this, I did some IV plots of some USB chargers I had lying around the other day, all here http://www.electronicsinoz.info/usb-charger-iv-plots/

A "trend" that is noticeable is the voltage out of these chargers is more like 5.2V, I can only assume to compensate for lead resistance.  Personally I particularly liked how the Samsung charger actually ramped up the voltage WRT current draw, again presumably to compensate for their known lead resistance.  Possibly you could implement something like that.

This is the sort of thing that if I needed a charger now, it was on a shelf next to a bunch of others in a shop and it was a bit more than the rest (maybe $20-30) I might just decide it to buy it. Unfortunately when I'm in front of a computer with time on my hands, I'm far too pragmatic about what I do with my money.  Therefore I can't see myself buying this online.

[free_electron]

Do you support PD charging ?

I wish .  If we can get this product off the ground we'd definitely like to be one of the early to market suppliers of a USB charger that supports the Power Delivery specification.  I'm not even sure a muliport charger for PD would make sense (at least if you tried to do 4 ports at 100W each you'd have a really hard time keeping any reasonable form factor).

It would be nice to have 1 port be PD compatible.

[Gallymimus]

Totally un-related to this, I did some IV plots of some USB chargers I had lying around the other day, all here http://www.electronicsinoz.info/usb-charger-iv-plots/

A "trend" that is noticeable is the voltage out of these chargers is more like 5.2V, I can only assume to compensate for lead resistance.  Personally I particularly liked how the Samsung charger actually ramped up the voltage WRT current draw, again presumably to compensate for their known lead resistance.  Possibly you could implement something like that.

This is the sort of thing that if I needed a charger now, it was on a shelf next to a bunch of others in a shop and it was a bit more than the rest (maybe $20-30) I might just decide it to buy it. Unfortunately when I'm in front of a computer with time on my hands, I'm far too pragmatic about what I do with my money.  Therefore I can't see myself buying this online.

Thanks for the feedback.  Actually you raise a good point.  We are probably going to include a user selectable "turbo" mode which pushes the voltage to the limit of the USB spec.  It should give a 10% charge speed boost.  It is similar to the line resistance compensation that you are talking about.

I like you am very pragmatic and don't dig on spending a lot on accessory products.  Sometimes though I do buy some really really nice things, especially if I use them every day.    Personally I'd be more inclined to have something like this on my desk rather than a little bundle of cables from wall warts.   My wife is certainly going to like this on the nightstand better than the power strip I have now hahahaha

I think audiophiles may go for it too after we get all the data on audio quality.

Thanks for sharing your findings on the IV curves.  Very cool.  Would it be okay to reference your work?

[Gallymimus]

Do you support PD charging ?

I wish .  If we can get this product off the ground we'd definitely like to be one of the early to market suppliers of a USB charger that supports the Power Delivery specification.  I'm not even sure a muliport charger for PD would make sense (at least if you tried to do 4 ports at 100W each you'd have a really hard time keeping any reasonable form factor).

It would be nice to have 1 port be PD compatible.

That's kindof what I was thinking too.  I don't think it would make it in this version of the product but I think that would make an outstanding V2.... Assuming PD takes off.  I hope that it does.

[Gallymimus]

Hey, I just want to thank everyone again for the thoughtful comments and criticisms.  We really appreciate it.

[Harvs]

I like you am very pragmatic and don't dig on spending a lot on accessory products.  Admittedly this isn't a product for me.  It's a product for an executive, business traveler, and the guy who has a putting green in his office .  I think audiophiles may go for it too after we get all the data on audio quality.

In a way I am your target audience, as I guess I'd fall into the "business traveller" category a lot.  I'm not saying I wouldn't buy it, but it's exactly the sort of thing I'd buy while I was traveling.  I'll be on my way to some S*@t hole somewhere, we'll realise we don't have a USB charger for some kit we need to use and if it happened to be there I could well choose it even if it was the most expensive one.  It's just not the sort of thing I would buy while shopping online at home.  Just some food for thought about potential distribution, I reckon airport stores would be a good target.

Thanks for sharing your findings on the IV curves.  Very cool.  Would it be okay to reference your work?

Of course, it's a website, you don't have to ask permission for that.

[Gallymimus]

I like you am very pragmatic and don't dig on spending a lot on accessory products.  Admittedly this isn't a product for me.  It's a product for an executive, business traveler, and the guy who has a putting green in his office .  I think audiophiles may go for it too after we get all the data on audio quality.

In a way I am your target audience, as I guess I'd fall into the "business traveller" category a lot.  I'm not saying I wouldn't buy it, but it's exactly the sort of thing I'd buy while I was traveling.  I'll be on my way to some S*@t hole somewhere, we'll realise we don't have a USB charger for some kit we need to use and if it happened to be there I could well choose it even if it was the most expensive one.  It's just not the sort of thing I would buy while shopping online at home.  Just some food for thought about potential distribution, I reckon airport stores would be a good target.

Thanks for sharing your findings on the IV curves.  Very cool.  Would it be okay to reference your work?

Of course, it's a website, you don't have to ask permission for that.

I gotcha, thanks.  Fancy airport stores would be a good place for it.  Where do I find the eevblog equivalent of sales and distribution forums

[Harvs]

We are probably going to include a user selectable "turbo" mode which pushes the voltage to the limit of the USB spec.  It should give a 10% charge speed boost.  It is similar to the line resistance compensation that you are talking about.

Have you had a chance to test that hypothesis?  I'd be interested to know if the majority of phone/tablets continue to pull a constant current across the 4.5-5.5Vin, or if they switch over to a constant power draw at some point in that range.

It would just seem a little odd to me, if a charge circuit was capable of charging at 10% higher rate by raising the input voltage within spec, why wouldn't a manufacturer like Samsung already do it?

[Gallymimus]

We are probably going to include a user selectable "turbo" mode which pushes the voltage to the limit of the USB spec.  It should give a 10% charge speed boost.  It is similar to the line resistance compensation that you are talking about.

Have you had a chance to test that hypothesis?  I'd be interested to know if the majority of phone/tablets continue to pull a constant current across the 4.5-5.5Vin, or if they switch over to a constant power draw at some point in that range.

It would just seem a little odd to me, if a charge circuit was capable of charging at 10% higher rate by raising the input voltage within spec, why wouldn't a manufacturer like Samsung already do it?

No I haven't tested it yet.  UGH so many things to test still

You are right.  It's hard to say whether it would work or not.  It really depends on if the SMPS front end in the phones is power regulated or current regulated.  If they limit the current drawn rather than power drawn it JUST MIGHT WORK!

It will be a tricky test.  Making sure the phone or tablet is off so that background tasks don't artificially impact the charging rate and making sure that the phone battery is discharged to a consistent level each test cycle will be important.  I need an intern!

[Harvs]

I don't think you need to get that complicated to start with.  Just hook up a lab supply to USB cable with an ammeter. With the phone off, and not fully charged vary the input voltage between 5 and 5.5V and see what happens to the current draw.  It'll be pretty obvious, either it'll stay flat or will drop with input voltage.

The tricky part is getting your hands on a reasonable sample set of phones so you can offer customers some degree of confidence as to the expected outcome.

[Gallymimus]

I don't think you need to get that complicated to start with.  Just hook up a lab supply to USB cable with an ammeter. With the phone off, and not fully charged vary the input voltage between 5 and 5.5V and see what happens to the current draw.  It'll be pretty obvious, either it'll stay flat or will drop with input voltage.

The tricky part is getting your hands on a reasonable sample set of phones so you can offer customers some degree of confidence as to the expected outcome.

Well you are right that's a perfectly good starting point, though in the experiments we've done so far current consumption is pretty inconsistent in general.  Nexus 7 2013 for instance draws 0.9 amps for a bit, then 1.15A for a bit and switches back and forth, though I should be able to adjust the voltage and look for an increase in those quantal states.

Maybe we should launch a donate your phone thread!

[Harvs]

My observations testing this theory (note test just done with shorted data lines.)

2013 nexus 7 - 5.1V and above (at the cable, so probably 5V at the device.)  It seems to draw a constant current.  No significant change to charge current across 5.1 to 5.5V.  If the voltage is reduced to 5V or below, there is a sharp decline in charge current.  Possibly it uses this as safety mechanism.

Galaxy S3 - Appears to be a constant power draw.  Once charging at a stable "high" current, the current reduces proportional to increases in voltage.

So yeah, bit of a mixed bag.  Need more phones to test.

[scientist]

For the techies out there it also reports voltage and current so you can be certain your expensive device is getting the precise clean charging power it deserves.

Wouldn't want any of that dirty charging power going into your pretty gold iPhone, would you now? 

I kid, I kid... but the market for this kind of thing doesn't seem very large.

[Gallymimus]

My observations testing this theory (note test just done with shorted data lines.)

2013 nexus 7 - 5.1V and above (at the cable, so probably 5V at the device.)  It seems to draw a constant current.  No significant change to charge current across 5.1 to 5.5V.  If the voltage is reduced to 5V or below, there is a sharp decline in charge current.  Possibly it uses this as safety mechanism.

Galaxy S3 - Appears to be a constant power draw.  Once charging at a stable "high" current, the current reduces proportional to increases in voltage.

So yeah, bit of a mixed bag.  Need more phones to test.

Sorry for the late response, I didn't seem to get an auto-notify?!?!

Cool, thanks for checking that out.  That is interesting.  I guess we'll have to get a hold of a bunch of different popular devices to check out.

[Gallymimus]

For the techies out there it also reports voltage and current so you can be certain your expensive device is getting the precise clean charging power it deserves.

Wouldn't want any of that dirty charging power going into your pretty gold iPhone, would you now? 

I kid, I kid... but the market for this kind of thing doesn't seem very large.

hahaha, no really that is the point!  There are a lot of people who want the best simply because it's the best.  I agree it is going to be a small market but that's the intention.  We want to fill a need that isn't being serviced by Anker, Belkin, and the chinese no-names.  Plus, we don't want to have to reduce the quality of our design trying to play the price cutting game with those entities.

  We're not looking to get rich, we're not looking to compete with chinese chargers and honestly we're not interested in spending time shaving 1/4 cent off the cost of a capacitor so that we can improve our margin.  We are interested in high end toys with high end parts.  We're engineers right?  We want to use the best performing designs and techniques which are rarely the cheapest.  If we can do that, and provide some nice things to a small group of appreciative people and make enough to cover the cost of engineering, we'll be happy as clams

Maybe we should sell gold plate coatings for iphones now that you mention it

[Gallymimus]

I have a Qi charger at my home and use it for my tablet each night.  It's OK, but hardly awesome.  It definitely serves it's purpose and for slow lazy charge overnight I love it.

Which devices / wireless charger are you using?  I find it's a pain to align my tablet over the coil on the charger, maybe you don't have that problem with yours.  Do all of your devices support the wireless charging pad you are using?

Sounds like a sucky charger. I have a few, all better than yours. I have a Nexus 5 charger that is magnetic, so the phone aligns itself naturally. I have an LG charge pad that fits into a car holder so the phone is always in the right place. I have a Panasonic Qi pad that uses a motor to position the charge head under the device automatically. Finally I have a cheap no-name charging pad and for some reason don't have a problem aligning stuff over it.

Oh yeah, your's sound much better.  I got one of the early ones and it was on sale.  I got it just to try it and tear it down and learn about it. 

[Gallymimus]

USB charging is going to be around for a while, Especially since the new charger spec (USB Power Deliver Spec 1.0 http://www.usb.org/developers/powerdelivery/) will support 12 and 20V and up to 5A.  We will likely see monitors and notebook computers powered via the new USB specs.  Wireless won't be getting there for some time.

So what you are saying is your device will soon be obsolete? Only kidding, but rather than spending so much time trying to shave a few minutes off charging phones and tablets you should think about adding more useful features. Stick a Qi compatible wireless charging pad on the top, or maybe two. Design an ultra-low power standby mode so it can be kept plugged in all the time. Panasonic offer that feature on some of their battery chargers, and it seems to use the voltage of the battery itself to turn on before switching to mains power. You could do the same with 5V USB power available from many devices.

Harsh

We'll look at the Qi.  It would eliminate the possibility of having an aluminum case as you'd dump all the antenna energy into it.  It would have to be a different product.

Great idea on the super low power mode.  That's actually something we were looking at doing so it's good to hear it's a potentially desired features.  Since we are going to have a micro in this we can put a lot of stuff to sleep and periodically "look" to see if anything is attached, and then bring things back online.

You don't happen to have a sense of what power consumption levels are desired for chargers when idle do you?  I can look up the energy start specs but I've actually not checked that out yet.

[PointyOintment]

A very small solar panel of the kind used for calculators could easily suffice, with a moderate size super capacitor.

Just use the supercap, and when it gets low, start up the converter briefly to recharge it. Either way, it's probably going to save only a few cents worth of energy per year.

[Balaur]

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

[nathancrum]

Patrick  can better answer the input power limits question than I, but I believe the multi-phase buck converter we're using is capable of accepting anything from 12V up to 40V input power.  Any notebook charger or vehicle power should certainly work.

We planned to include the PSU for all orders because we're largely dependent on a quality PSU for safety and it is the only way we could reliably get enough quantity to offer it at a reasonable price.  However - the way it is designed, the output power quality is largely independent from the PSU and we could potentially offer it without one if there's enough interest.  Most people however - prefer a turnkey product.

A "direct" 5V output is not a bad idea - although a USB adapter output cable would be even easier to implement.

A travel and/or battery powered version is definitely in our sights for a next step, but we're trying to tackle this one design at a time.

Thanks for the questions & feedback.

[Gallymimus]

It's the principal. Standby wastes a lot of power, and even if it is only a small amount we should make an effort to avoid it. Whatever solution Panasonic came up with seems to be very low cost and very effective.

It's funny,

I actually saw a small USB wall wart... I think from AT&T, that was super low power and quoted 0 standby current.  It actually had a relay inside that clicked on when the charger was operating.

[Balaur]

...

Hey Nathan. Thank you for your quick and informative reply. Appreciated!

[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.