The Exigo: A high performance USB charger

[Gallymimus]

I am frustrated with car chargers and am in the process of designing one of my own for my personal use, so I've done quite some research on the subject. So here are some comments:

I agree OEM chargers can be underperforming too and I don't think it is just due to the voltage drop of the cable. Simply put, a tiny, tightly packed, plastic, non ventilated charger is going to overheat no matter what and thermal protection will kick in limiting the current.

Car chargers are even worse, because they are totally engulfed by the lighter socket. To make things worse, the lighter socket is usually in the center console of the car, right above the exhaust pipe path, so it is already warmer than the rest of the car's cabin.

Your product will encounter the same problem if there's no proper thermal management.

The price for your product seems a bit steep at first glance but is probably not totally out of whack. A proper DC to DC converter, negotiation chips for each port, mcu and OLED screen is going to cost money. Heh, a good DC to DC controller chip alone can cost several times more than a fully assembled chinese crap charger.

I have no doubt that your product does what it advertises and that the final price is fair considering the BOM. Problem is that Joe Average will scream bloody murder if the product was priced at $50, let alone $290!

I think you are well into diminishing returns, basically trying too hard to solve a minor problem that most people do not care about.

Thanks for the comment.  It is amazing the crap they put into $5 chargers and you are right, a good regulator IC and quality mosfets cost more by themselves.  We are intentionally on the high side of that cost/value curve, but we wanted to take a shot at the very best.  We'll see how it goes.  If it doesn't work out we'll regroup, pivot, and make another go at it.

[Gallymimus]

Does this run on separate 12 v or so power supply?

You plan to buld your own power supply or buy something readily availlable?
Fancy aluminium box for crazy price, included with cheapets chinese 12v power brick that makes all yourlow- noise, reliability, safety marketing talk worthless? 
 

Sorry, only checked your website and skipped kickstarter website altogether. So it runs on external 24v power supply.

How did you budget your agency approval tests, ie CE and FCC emc sirectives among others?

Actually one of the reason's we'll be using a pre-approved off line power brick is that it removes the CE and UL testing requirements.  FCC is technically still required, unintentional radiator compliance doesn't cost much (few thousand).

As for your other comment regarding a cheap power brick, we don't want to use crap, but we would like it to be reasonably cost effective.  As for the quality of the power brick, the multiphase and LDOs do a great job cleaning up whatever crap might come out of the power brick.

[Gallymimus]

Mike, I'm afraid you are quite wrong on a few points. 

One, prior to the IPAD 4, nothing would draw more than 2.1A now the max is 2.5.  What do you think will happen in 6mo as devices become more power hungry?  3A is very reasonable and future looking.

Anything that draws this much will be very much the exception, and will come with its own charger. Paying to provide multiple ports with that capacity is  a waste of money.

Two, Linear regulator? Really?  If you can find a modern product that uses a linear regulator in it send me your paypal email and I send you $20!!!

Bluetooth headsets
Bluetooth keyboards
Pretty much anything with a low capacity cell.
A specific example :

paypal : mike @ whitewing.co.uk.

Seriously though,  Everything has a PMIC (Power Management Interface Controller) in it.  The 5.5V is really about overcoming the voltage drop in the cable so that the DEVICE see's  5.0 to 5.5V.

It doesn't add to your credibility that you don't even know how to use an apostrophe.

Most USB cables have an impedance on the order of 100 to 200 mohms.

It's DC, the appropriate  term is resistance

At 2A that's a LOT of voltage drop.  The voltage boost really helps with this.  It's also why we are going to be supplying low gauge USB cables.

True - there are a lot of crappy USB cables out there. But anything supplied with a 2A charger is going to have a decent cable. The problem is when people lose/break it and use a cheap crappy one.

It's an unnecessarily over-engineered expensive solution to a problem very few people will see as worth spending that much to solve, so you're trying to hype it up with irrelevant details and marketing waffle.
The vast majority of people will leave stuff to charge overnight, so charge time will not be an issue for them.

hahah, chasing me after apostrophes?    You are right I must be a terrible engineer.  Does your simple website make you a bad engineer?  I doubt it, you are probably awesome at what you do.

 using devices that aren't really in the realm of this product as a reason that linear regulators mean our product sucks?  Really?  okay, so don't buy it for a chinese bluetooth headset, who cares about that, clearly our target is cell phones and tablets which do use switching PMICs and the LDO comment is still a BONER.  Does boner even mean anything in this context or did I make up a new meaning for it? 

Impedance vs resistance?  Really?  Trying to ding me on that?  I won't even go to the trouble to say it's the same thing if your imaginary contribution to the impedance is zero.  BUT, I know you know I know you already know that.  Yer just trying to get under the proverbial skin.   

That's good that your grasping for reasons to hate, that means any real issues with the product have been fully discussed to completion. 

Mike in all seriousness, thanks for the interest and comments.  I had no expectation that we'd get any less criticism on EEVBlog

How long have you been consulting for anyway?

[Gallymimus]

I use this Anker 40W 5-Port Charger for both charging and powering any 5V device  (replaces 5 wall-warts) :

http://www.amazon.co.uk/dp/B00GYNW1TA

This is an awesome basic charger.  I have 2 of them!

[Gallymimus]

Wow, that is a 250 dollar USB charger, without hub functionality, wireless charging or built in battery

Turns out you can't charge a device at high currents while there is a data connection.  In fact the data lines are forced to specific voltages in order to communicate the charger's current output capability.

I did a lot of research on USB charging and it's actually much more of a PIA than most people realize.

Wireless charging and battery also present problems for high speed high power charging.  I've got a Qi charger and it never charges as fast as a wired connection.  Battery solution is a different kind of product and no one talks about what happens when the battery dies in a few years, buy a whole new charger I guess.

OLED display is my favorite feature on the Exigo.  But I'm a data nerd.

My problem is that there is nothing in it, which would justify the price.
Yes, wireless charging is slow, I give you that. There is usually a 6-7 hour period in my day, when I'm not doing anything.
There are battery product with replaceable cells. And I dont need a OLED display. Why would I? There is a screen on my phone/tablet/ebook which tells me when the charging is complete.
But seriously, you can probably sell this product. It already sells. Although this is an electronics forum, people kinda aware how much something should cost. Just a quick calculation:
60W laptop power supply (FSP): 25 USD
4x LMZ22005 5A SIMPLE SWITCHER® Power Module 4*6USD
Charging port contoller: TPS2513A 2*1USD
PCB: 5 USD in quantity (European manufacturer)
Assembly: About 4-5 USD, European manufacturer
Housing: I cannot give you an estimation.
OLED 20 USD
Whatever MCU platform 10 USD

That is about 100 USD + housing.
And I chose deliberately stupidly expensive components.

So you have 4*4A charging capability. To charge 4 tablet, as nothing else seems to take this amount of power. Well, I don't have 4 tablets.

yer not terribly far off, OLED is actually quite a bit less.  Don't forget DACs for trimming the output, quality LDOs for noise for the audiophiles. 

Also don't forget the all important margin, we have to sell it, make money, and leave room for distribution and retail which is unbelievable, especially when you don't have leverage.  Trust me we're not trying to rip off the world, or we'd have done a project on indiegogo .  How much do you think gross margin should be, then markup for wholesale distribution, then retail?

[Monkeh]

What an amusingly pointless device, and yet I have a topical question.

Where have you found USB A receptacles rated for 3A continuous?

[mikeselectricstuff]

hahah, chasing me after apostrophes?    You are right I must be a terrible engineer.

It just looks bad - If you don't care about getting that right, what else don't you care about getting right?

Does your simple website make you a bad engineer?

Simple, yes. but correctly spelt and punctuated (typos notwithstanding).

using devices that aren't really in the realm of this product as a reason that linear regulators mean our product sucks?  Really?  okay, so don't buy it for a chinese bluetooth headset, who cares about that, clearly our target is cell phones and tablets which do use switching PMICs and the LDO comment is still a BONER.

Just pointing out that your out-of-spec high output voltage could potentially cause problems.
 I sort of got the impression that a major point the whole point is that you have one charger for all your stuff.

How long have you been consulting for anyway?

About 30 years

[fubar.gr]

Just pointing out that your out-of-spec high output voltage could potentially cause problems.
 I sort of got the impression that a major point the whole point is that you have one charger for all your stuff.

This is simply a feature most USB charging controller chips have. If the controller detects a high current draw device (by setting the voltages on D+/D-) and some other specific conditions apply then it will raise the voltage a bit to overcome the voltage drop of the cable.

It poses absolutely no threat for devices with linear regulators.

[Monkeh]

We never would have thought it was true until we tested it and actually saw a significant improvement over OEM (specifically IPAD 4, and Samsung Galaxy S4).  I am pretty sure it was because of cable losses.  I can understand Samsung not being able to predict cable losses with a variety of USB micro cables

But they modelled the supplied charging cable pretty much perfectly.

You did test that cable, right?

[tszaboo]

yer not terribly far off, OLED is actually quite a bit less.  Don't forget DACs for trimming the output, quality LDOs for noise for the audiophiles. 

Also don't forget the all important margin, we have to sell it, make money, and leave room for distribution and retail which is unbelievable, especially when you don't have leverage.  Trust me we're not trying to rip off the world, or we'd have done a project on indiegogo .  How much do you think gross margin should be, then markup for wholesale distribution, then retail?

Yes the profit margin. Many KS project fails to understand how this works. Kickstarter is not a platform to sell premium products with premium price. People dont want that. It is not a sale platform.
At kickstarter people actually lend their money to "kickstart " the production of something. You know, the money otherwise you end up getting from a bank with interest or making shares or some other way, which costs you money.
Asking for a loan to make something with premium profit is not honest IMHO. Especially if it is a consumer product, which typically sells with very low profit margins. Alternative products sell for the fraction of the price. The last 1 or 2 days two units were sold.

I always ask people selling things: Tell me honestly: would you buy this?

[Monkeh]

It appears we scared them off by not accepting their project with open arms as the future of USB charging devices.

[Flump]

haha 

[classical]

The automatic selecting of the correct circuit to provide "fast charging" is a very good and helpful thing.
I guess, a price sticker of 10 or 15 USD above the "Anker 40W, 5Port" charger mentioned by mhwlng would motivate some customers.

[marcan]

The automatic selecting of the correct circuit to provide "fast charging" is a very good and helpful thing.
I guess, a price sticker of 10 or 15 USD above the "Anker 40W, 5Port" charger mentioned by mhwlng would motivate some customers.

The Anker charger already does that. Marketingese aside, that's what PowerIQ is.
http://www.ianker.com/poweriq/poweriq.html

TI has a chip that does this for you automatically:
http://www.ti.com/lit/ds/symlink/tps2543.pdf

This isn't news. Yes, most el cheapo USB chargers out there are garbage, but you can get a decent 25W 4-port charger for about 15 bucks. I have one of those; tore it apart and it looks solidly built on the inside, and the output was pretty clean on the scope, and I'm never going to pull more than that much power out of 4 ports (my only high-current device is a tablet); all I did was remove the stupid Apple style divider resistors and turn the ports into standard DCPs. I can see shelling out $50 for a premium charger, but $250 is just way past the sensible pricing threshold.

[classical]

Thanks, marcan for the info about the Anker PowerIQ. I also just found the TI TPS 2511 http://www.ti.com/lit/ds/symlink/tps2511.pdf doing the same.

[mikeselectricstuff]

I think the kickstarter figures say it all...

[tszaboo]

I think the kickstarter figures say it all...

Wow, they sold it to other five people other than family members.

[classical]

The 0.5A of slow charging could be not enough to enable continuous operation for tablet (status display for home automation) or smartphone (navigation).

Gesendet von meinem K1 turbo mit Tapatalk

[amyk]

clearly our target is cell phones and tablets which do use switching PMICs

How many of them do?

This is the block diagram of the charger part of a PMIC used in a huge number of smartphones, including the one I have. Does this look like a switching charger to you?

[tom66]

I'd like to see a charger which interfaced with an app on the phone. When the battery reached 90%, it would stop charging.

Most phones charge to 4.25V to get the absolute max capacity out of the cell, but if you stop charging at 4.15V, the cell lasts much longer. (And stop discharging below 3.2V.)

Ever wondered how you can get long life out of electric car batteries? Don't charge them fully. Tesla stop at 4.16V/cell abs max (and 3.2V/cell abs min) and rate the batteries for 8 years in a punishing automotive application.

[Dago]

Ever wondered how you can get long life out of electric car batteries? Don't charge them fully. Tesla stop at 4.16V/cell abs max (and 3.2V/cell abs min) and rate the batteries for 8 years in a punishing automotive application.

Might not be a fair comparison to compare Tesla batteries to mobile phones because the chemistry is not the same (currently tesla is using Panasonic cells with lithium-nickel-cobalt-aluminum oxide chemistry which has a longer lifetime).

[Refrigerator]

The 0.5A of slow charging could be not enough to enable continuous operation for tablet (status display for home automation) or smartphone (navigation).

Sure, but who wastes power keeping their tablet display on all night while they charge it up?

I guess he spends his whole night watching porn.
Fast charging is pretty punishing to mobile devices that use Li-Ion batteries but many devices use them because of their high evergy density. Some use Li-Po batteries that can achieve high charging current but there aren't many out there.
IMO if you try to fast charge Li-Ion batteries they just become ticking bombs waiting to burst into flames.

[brabus]

(...)
Two, Linear regulator? Really?  If you can find a modern product that uses a linear regulator in it send me your paypal email and I send you $20!!! 
(...)

Samsung Galaxy SII i9100 uses a linear regulator.
I wait before listing the next products, because I have a question: do you give 20$ for every one? 

I have a more serious technical question. Is the output voltage of your super-charger fixed to 5.5V, in every circumstance?
If this is true, may I ask you the reason for such a technical choice?
Please do not be offended, I just want to understand your point.

Last question: do you offer any form of warranty for damages caused by your out-of-spec charger?

[CanadianAvenger]

What you really need is a special cable with sense wires so that the output can be regulated taking into account cable losses.

You can probably do that now without a special cable, by taking advantage of the fact that there is a pull-up on D+ or D- that is used to identify LS or FS/HS, and device presence.

[Monkeh]

Last question: do you offer any form of warranty for damages caused by your out-of-spec charger?

What's out of spec about it?

Actually, you could just characterise a normal cable and vary voltage based on current draw.

You mean like Samsung do with their 2A chargers?