Sick of Apple chargers? Solution: SupperCharger+, the Next Generation

[SharpEars]

So, I've had it with Apple mobile device chargers. You get them from Apple for $19 for the 12 Watters. Or, you get them on eBay for $5 for the Chinese 12 Watt knock offs. Both put out 5 V, more or less via a female USB connector (definitely less in the case of the knock offs).

It's not the price that bothers me. It's how slow the charging process is - quick charge my ass. So:

The bad: I want to charge my device as quickly as possible. Apple chargers just don't cut it. Chinese knock offs that drop their voltage to 4.75 V when loaded cut it even less than the Apple ones. The device limits the maximum rate of charge. The theoretical max is stated as 2.4 A at 5 V (i.e., 12 W).
The other bad: When using one of those Apple chargers, you're charging blind. I want to be able to see how many volts my supply is producing and how many amps of current my mobile device is pulling.
The other other bad: I want a clean supply with low ripple. Does it really matter? Probably not, but I want it anyway! Real Apple adapters have less ripple. Chinese knockoffs ripple like a lake under a thunderstorm.
The other other other bad: Apple's ultra thin lightning cable at a 2 A load sure drops some serious volts. I might consider using a shorter lightning cable not made by Apple. I might also consider taking a genuine Apple cable and cutting it close to the lightning connector to minimize the cable's length.
The good, finally: Apple devices can actually receive up to 5.30 V and still charge just fine. The charge current increases as the voltage increases, because the resistance of the device appears to stay constant. In other words the device does not adjust its load as the voltage increases (up to a point). This is true until the OVP kicks in at somewhere in the 5.4-5.5V neighborhood (will need additional testing to isolate this point across multiple devices).
The ugly: To charge at max current, you have to present a constant (and fairly accurate, +/- 3-5%) 2.7 V on the D+ and D- USB pins to fool the Apple mobile device into believing that it is in fact connected to a 12 W charger. This means that whatever I build will either need very good load regulation, so that I can use a resistor ladder divider to create the 2.7V or I will need an additional regulator for the 2.7V data line requirements.

So, enraged by slow charging times and fueled by my OCD, I've decided to build myself a charger - the SuperCharger+. I will spare no expense (OK, up to $300)! Saving money is not the object here. Weight of charger is not the object here (OK, maybe a little, I need to be able to transport it on my body or in a bag to work - its final home). I want:

• The quickest charge possible
• The ability to charge two disparate devices (e.g., iPhone and iPad) simultaneously or maybe even an iPad and a high current Android device that requires totally different D+/D- voltages
• Ability to monitor what is happening (i.e., voltage/current at/of the load).

The idea: Build the SuperCharger+. What is the SuperCharger+, you ask? Well, it will most likely consist of the following connected together:

1. Take a 5V +/- 10% adjustable power supply with sense screws ($300 budget on this). This puppy better have awesome load regulation (i.e., not 5-10% like ATX supplies). Hell, it might as well be linear to cut down on the ripple, too. The line input will be a steady 120 V (US), so I don't care much about line regulation.
2. Take two in-line USB dongles that show the voltage/current at/consumed-by the devices being charged. (Note: High end, not the wildly inaccurate $1 Charger Doctors/Shmuckders)
3. Create a voltage divider to take care of the 2.7 V USB D+/D- pin requirements (i.e., fool the Apple device into believing it's connected to an Apple 12 W charger)
4. Compensate for the voltage drop of the USB dongle from item #2 by using the power supply's (from #1) voltage sense inputs
5. Tune everything so that the output is a stable 5.3 V, independent of device load currents (the hard part)

The result - Be able to charge my devices as quickly as possible and have the ability to check periodically to make sure that they charge at the max current and max voltage they are configured to handle.

If you read this far, I am interested to hear your thoughts on my crazy (or not?) idea.

Update: This rant is about Apple chargers, but I have Android devices and they need charging too.
Update 2: This thread will be updated as progress is made on this project. For now I am at the power supply selection stage and your recommendations are welcome.

[IanB]

Meh. Much ado about nothing. Sorry.

[SharpEars]

Meh. Much ado about nothing. Sorry.

One man's nothing is another's fun project idea . Also, how many times have you had to leave the house/work and discovered your phone is dead? I have, many times! I wanted as quick a charge as I could get then and there. It would need to last me the hour (several hours?) I would be away. I didn't want to pack a battery pack or use a car charger. I just wanted to charge and go.

My common scenario is I have to leave in 5 mins and discover that my phone is dead or nearly dead. I want to get it charged as much as I can in that time frame. When your phone is about to die, every little bit counts.

[Mr.B]

2. Take two in-line USB dongles that show the voltage/current at/consumed-by the devices being charged. (Note: High end, not the wildly inaccurate $1 Charger Doctors/Shmuckders)

If you want high end... Here it is...

Forum member here iloveelectronics has an ebay store selling the YZXstudio USB Power Monitor.
Here: http://www.ebay.com/itm/USB-3-0-Power-Monitor-Red-YZXstudio-Voltage-Current-Meter-High-Resolution-OLED-/171606912751

He also runs a sales thread on the forum.
Here: https://www.eevblog.com/forum/buysellwanted/franky's-sales-thread/msg694265/#msg694265

I purchased a couple of them and they are very accurate.

[SharpEars]

2. Take two in-line USB dongles that show the voltage/current at/consumed-by the devices being charged. (Note: High end, not the wildly inaccurate $1 Charger Doctors/Shmuckders)

If you want high end... Here it is...

Forum member here iloveelectronics has an ebay store selling the YZXstudio USB Power Monitor.
Here: http://www.ebay.com/itm/USB-3-0-Power-Monitor-Red-YZXstudio-Voltage-Current-Meter-High-Resolution-OLED-/171606912751

He also runs a sales thread on the forum.
Here: https://www.eevblog.com/forum/buysellwanted/franky's-sales-thread/msg694265/#msg694265

I purchased a couple of them and they are very accurate.

Wow, nice! I already have one of these that I picked up for $8 on eBay:



But the one you linked to is much better, both in terms of functionality and precision (maybe even accuracy) at the 100 uA level.

[Melt-O-Tronic]

By "SupperCharger+", do you mean that it only charges during dinner time?  Or will it work at lunch too?   

My Apple experience is pretty limited (iPhone 6), but I've not had any issues with charging at all.  In fact, it charges much faster than all my Android devices, charge lasts longer, the display is informative & accurate with respect to charge level, etc..  So I guess I'm not seeing the pain point.   

[mtdoc]

I have one of the YZX monitors from Frankie as well. I agree, their great, especially the small size.

But for even higher end, the PortaPow premium USB power monitor is even better.

Resolution is 0.0001A and 0.0001V.

But, I agree with others. I've had no issues with Apple charges over many years.

[LabSpokane]

Before you spend much more effort criticizing Apple's chargers, you might do well to stick one on an oscope and actually see the output. Spoiler: they're solid - particularly in comparison to the cheap, off-brand models.

[Richard Crowley]

Before you spend much more effort criticizing Apple's chargers, you might do well to stick one on an oscope and actually see the output. Spoiler: they're solid - particularly in comparison to the cheap, off-brand models.

Can you explain whether that has any importance in the Real World?

[suicidaleggroll]

But, I agree with others. I've had no issues with Apple charges over many years.

I don't get it either, they're perfectly fine.

I also don't get what this fascination is with charging faster.  The faster you charge the battery, the more damage you do to it, especially if you start trying to "fool" the internal charging logic by cranking up the input voltage as high as you can.

[wraper]

I might consider using a shorter lightning cable not made by Apple.

Most of the knockoff cables have super thin strands. Quiet likely you'll get more voltage drop than with longer original cable.

The result - Be able to charge my devices as quickly as possible and have the ability to check periodically to make sure that they charge at the max current and max voltage they are configured to handle.

And waste more time of your life on designing/making than would ever save by "faster" charging 

[SharpEars]

This is in reply to several people that raised the concern that the Apple chargers are solid, if you monitor them (CV), hook them up to a scope (ripple and load regulation), etc...

Yes, but what they do not do is put out a constant 5.3 V output independent of load (charging) current. The SuperCharger+ will allow for the charging of up to two devices that will be getting 5.3 V (constant and well regulated) regardless of current load and whether they like it or not. This is the difference - up to 0.3 V extra per port.

Also, in answer to this having a detrimental affect on the battery being charged, it's all within spec, the USB 3.0 spec (max VBUS voltage is 5.3 V), so Apple has to have allowed for this and I will be just taking advantage of it.

[SharpEars]

I might consider using a shorter lightning cable not made by Apple.

Most of the knockoff cables have super thin strands. Quiet likely you'll get more voltage drop than with longer original cable.

The result - Be able to charge my devices as quickly as possible and have the ability to check periodically to make sure that they charge at the max current and max voltage they are configured to handle.

And waste more time of your life on designing/making than would ever save by "faster" charging 

You do realize that I can just trim the USB Type A male connector part of the lightning cable to shorten it and still keep the lightning connector side none the wiser, while cutting resistance by a factor of four or five.

[Monkeh]

This is in reply to several people that raised the concern that the Apple chargers are solid, if you monitor them (CV), hook them up to a scope (ripple and load regulation), etc...

Yes, but what they do not do is put out a constant 5.3 V output independent of load (charging) current. The SuperCharger+ will allow for the charging of up to two devices that will be getting 5.3 V (constant and well regulated) regardless of current load and whether they like it or not. This is the difference - up to 0.3 V extra per port.

Also, in answer to this having a detrimental affect on the battery being charged, it's all within spec, the USB 3.0 spec (max VBUS voltage is 5.3 V), so Apple has to have allowed for this and I will be just taking advantage of it.

You are making the assumption that this will increase the battery charging current. This could easily not be the case.

[wasyoungonce]

I've pulled apart and repaired apple chargers.  One thing to note...the USB power pins (on the charger socket) get burn't (carbon'd up) due to the excessive current.   USB was only supposed to be ~ 500mA ~1A max and at max current this is really exceeding the ability of the contacts of these pins....IMHO Apple is almost pushing these too much.

[SharpEars]

This is in reply to several people that raised the concern that the Apple chargers are solid, if you monitor them (CV), hook them up to a scope (ripple and load regulation), etc...

Yes, but what they do not do is put out a constant 5.3 V output independent of load (charging) current. The SuperCharger+ will allow for the charging of up to two devices that will be getting 5.3 V (constant and well regulated) regardless of current load and whether they like it or not. This is the difference - up to 0.3 V extra per port.

Also, in answer to this having a detrimental affect on the battery being charged, it's all within spec, the USB 3.0 spec (max VBUS voltage is 5.3 V), so Apple has to have allowed for this and I will be just taking advantage of it.

You are making the assumption that this will increase the battery charging current. This could easily not be the case.

I have empirically tested this and in fact it does increase the current until a cutoff voltage is seen at the device being charged. There is a built in safety mechanism that cuts the current at a certain, let's call it, overvoltage, a sort of OVP.

5.30 is well below the OVP and within the guidelines of correct and acceptable USB voltage.

[SharpEars]

I've pulled apart and repaired apple chargers.  One thing to note...the USB power pins (on the charger socket) get burn't (carbon'd up) due to the excessive current.   USB was only supposed to be ~ 500mA ~1A max and at max current this is really exceeding the ability of the contacts of these pins....IMHO Apple is almost pushing these too much.

Thanks for letting me know, I will check the female Type A USB socket periodically on the final charging unit and clean and/or replace it. It's going to cost me a total of $0.25 to do so (and some soldering, of course). With an apple adapter, assuming you can't clean/repair it, you're out $19 at current prices.

Additionally, I may cut off the USB Type A male end from a lightning cable and skip the whole USB end of the equation, plugging in the actual cable strands into my charging board and the lightning end into the device to be charged. Running a parallel micro-usb terminated cable (with dangling wires on the other side) will enable me, via a screw terminal for example, to be compatible with Android devices as well.

All food for thought as I make my nefarious plans for world domination the SuperCharger+ .

[Monkeh]

This might also be an interesting time to point out that many devices use linear charge controllers, which means you're just increasing heat dissipation..

But you need your phone charged five minutes sooner.

[SharpEars]

This might also be an interesting time to point out that many devices use linear charge controllers, which means you're just increasing heat dissipation..

But you need your phone charged five minutes sooner.

I don't think that the change in current resulting from a change from 5.0V to 5.3V will result in a very significant change in heat buildup within the device itself. Mobile devices are often charged in purses, on top of hot laptops, in one hundred degree climates, under the sun and who knows what else. They are designed to handle these extremes. The SuperCharger+ is going to sit in a climate controlled office that is kept at seventy degrees Fahrenheit with excellent air circulation at all times. It doesn't get much better than this for heat reduction, so I do not foresee a heat issue when the actual load and surrounding environment are taken into account.

[wasyoungonce]

Some info on Ken Sherrif's blog about Apple chargers.
http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html

[rs20]

Geez, there's a lot of hate on this thread. Haven't we all done pointless* projects in the past? Isn't it more about the journey than the end result?

* I'm not saying the OP's project is pointless, but even if it was...

This might also be an interesting time to point out that many devices use linear charge controllers, which means you're just increasing heat dissipation..

Would that explain the increased current draw seen by the OP at higher voltages? A linear reg would have more-or-less constant input current, right?

Given the voltage drop that can occur over a cable at high currents, it seems legit to up the voltage at the charger end. I doubt there's a need for having sense wires running to the phone end of the cable; although it would be very interesting for the purposes of investigation. As an alternative, you could measure the internal resistances of various cables by replacing the phone with a short circuit, and seeing what the voltage drop is around that loop for typical charging currents.

[Mr.B]

How to fast charge your phone:
1. Throw iPhone in the rubbish.
2. Buy a Samsung Galaxy S6

The charger is 18w.
Runs 5V @ 2A unless it detects that it is plugged into an S6, then steps it up to 9V @ 2A.


<<<Exits quickly before the flaming starts...

[WZOLL]

What Iphone device do you have. Some can only charge at 1A no matter the wire or charger.

[BradC]

I have empirically tested this and in fact it does increase the current until a cutoff voltage is seen at the device being charged. There is a built in safety mechanism that cuts the current at a certain, let's call it, overvoltage, a sort of OVP.

5.30 is well below the OVP and within the guidelines of correct and acceptable USB voltage.

I'm not ragging on you and I'm not being negative. I'm actually genuinely interested in the figures. Have you actually measured this and what sort of current increase are you seeing (in actual numbers)?
What you say makes perfect sense from a logic perspective. I'm actually interested in the hard data to see *how* much of a speedup this will give you? (and me if I build one).

I have the iPad 3, which happens to be the unit with the longest charge time, so anything greater than 10% increase I'd find interesting.

[SharpEars]

What Iphone device do you have. Some can only charge at 1A no matter the wire or charger.

I have an iPhone 5 (aware of the 1 A limit, but that's 1 A at 5 V), so I am trying to break 1 A. My iPad Air 2 can theoretically max out the 12 W Apple adapter (so 2.4 A, there). I want to push that to the limit as well. Both devices have OVP, so no harm in finding when that kicks in.

[SharpEars]

How to fast charge your phone:
1. Throw iPhone in the rubbish.
2. Buy a Samsung Galaxy S6

The charger is 18w.
Runs 5V @ 2A unless it detects that it is plugged into an S6, then steps it up to 9V @ 2A.


<<<Exits quickly before the flaming starts...

And if I were to buy a Galaxy S6, I would be looking for ways to charge that faster. You see, the phone and charger ultimately don't matter when you want to charge as quickly as possible - the chargers all suck, because they're two dollars worth of parts pieces of crap being sold to you for tens of dollars.

[SharpEars]

I have empirically tested this and in fact it does increase the current until a cutoff voltage is seen at the device being charged. There is a built in safety mechanism that cuts the current at a certain, let's call it, overvoltage, a sort of OVP.

5.30 is well below the OVP and within the guidelines of correct and acceptable USB voltage.

I'm not ragging on you and I'm not being negative. I'm actually genuinely interested in the figures. Have you actually measured this and what sort of current increase are you seeing (in actual numbers)?
What you say makes perfect sense from a logic perspective. I'm actually interested in the hard data to see *how* much of a speedup this will give you? (and me if I build one).

I have the iPad 3, which happens to be the unit with the longest charge time, so anything greater than 10% increase I'd find interesting.

The current does increase. I will post the actual figures for various (Apple) devices and maybe even an Android device or three when the project is complete.

[SharpEars]

I've finalized my choice of power supply and it's costing me just south of $25 (each, I bought two). Remember, I need to be able to charge two 2.4 A devices at once at 5.3 volts, so the PS has to be up to the task. The reason I got two supplies (so capability to charge four devices total), was so that I can keep one at home and one at work.

Now, after reading this far and pondering my crazy requirements, I am sure you are all wondering what an OCD freak like me got for the power supply. Feel free to post guesses and I will post more info over the weekend when I have the items in possession and I make some measurements to prove to myself that I made a good decision. (Pics will be up in any case, since I promised to keep you all abreast of my progress).

[amyk]

How much does the current increase? In other words, what's the input impedance?

LiPo batteries are charged with CC, followed by CV. The CC part of the charging curve is really current-regulated and raising the input voltage is, if the charger is a linear regulator, just going to cause it to dissipate more power - the current into the battery won't increase.

[rs20]

LiPo batteries are charged with CC, followed by CV. The CC part of the charging curve is really current-regulated and raising the input voltage is, if the charger is a linear regulator, just going to cause it to dissipate more power - the current into the battery won't increase.

You're assuming that with a voltage of 5V at the charger, the phone is actually limited by that CC current. I dare say that's a completely unfounded assumption (and seemingly disproved by the OP's assertion that the current does increase) -- phones compliant with standard X (I forget the name) will look for voltage sag from the charger as an indication that the charger is at its limit, and will be current limited by the charger instead, i.e. charging current = min(LiPo CC, charger capability).

[jwm_]

Anker's chargers will bump the voltage up above 5 depending on current draw to speed up charging and account for sag in the line. I have been quite happy with mine. They also "do the right thing" so that most any device detects it as a fast charger and draws full current.

http://www.ianker.com/poweriq

[Mr.B]

How to fast charge your phone:
1. Throw iPhone in the rubbish.
2. Buy a Samsung Galaxy S6

The charger is 18w.
Runs 5V @ 2A unless it detects that it is plugged into an S6, then steps it up to 9V @ 2A.


<<<Exits quickly before the flaming starts...

And if I were to buy a Galaxy S6, I would be looking for ways to charge that faster. You see, the phone and charger ultimately don't matter when you want to charge as quickly as possible - the chargers all suck, because they're two dollars worth of parts pieces of crap being sold to you for tens of dollars.

Well, I started off trying to offer something constructive - see my first post in this thread.
The above post is just in jest, I own both Apple and Samsung devices, and do not have serious complaints about any of them.
However, you appear to just be a troll.

What makes you think you can "trick" a phone into charging fast enough to suit your narrow minded objectives?
You said "And if I were to buy a Galaxy S6, I would be looking for ways to charge that faster."
I am sure that the engineers at both Apple and Samsung are consistently being told by the marketing wankers "Make that phone charge to at least 50% in 3.1 seconds", while the engineers think to themselves "Get fucking real!".
So nothing delivered by companies with billions of dollars of research budget would be good enough for you?
You think you can do better?
Dick.

Edit: Sorry, I withdraw that... i don't want the mods to ban me... I like this forum too much.

[Ian.M]

Get a phone with easily interchangable batteries + a spare battery then hack a camera battery charger to match the terminals on the phone battery.   Charging the phone now takes under a minute!   

Incidentally,I suggest editing the topic title to "Sick of Apple?".  If you don't like the behaviour/performance, don't buy the kit! 

Good LiPO batteries can reach 250Wh/Kg.  Current Supercapacitors reach 30Wh/Kg. so an 'instant' charging phone would have to be much bigger.  Also high current circuits need more copper, bigger caps, more ferrite in inductor cores, more silicon area and of course far more geatsinking so there wold be a knock-on effect on the size of the rest of the phone.   If you have the funding to commission the design from any leading phone manufacturer, an 'instant' charging phone could be on the market by Christmas, but it would be the size and weight of half a house brick and would need direct connection to a car battery's terminals  for 15 seconds to charge it! 

[SharpEars]

Well, I started off trying to offer something constructive - see my first post in this thread.
The above post is just in jest, I own both Apple and Samsung devices, and do not have serious complaints about any of them.
However, you appear to just be a troll.

I also own both Apple and Samsung devices, as I stated previously, and I can assure you that I am not trolling on this issue.

What makes you think you can "trick" a phone into charging fast enough to suit your narrow minded objectives?
You said "And if I were to buy a Galaxy S6, I would be looking for ways to charge that faster."
I am sure that the engineers at both Apple and Samsung are consistently being told by the marketing wankers "Make that phone charge to at least 50% in 3.1 seconds", while the engineers think to themselves "Get fucking real!".
So nothing delivered by companies with billions of dollars of research budget would be good enough for you?
You think you can do better?
Dick.

Edit: Sorry, I withdraw that... i don't want the mods to ban me... I like this forum too much.

OK, now let's talk about your about quote, minus the name and troll calling. The object of a company is to make money. If they can build a 2 dollar charger that fits the bill and sell it for $29 (the 12W charger's original price), more power to them! Also, I have measured the actual voltage output of the Apple 12W adapter and it puts out 5.1 V with no load and just over 5V with a 2A load, an empirical statement rather than pointless blabbing and theory crafting. Having in addition to this measured the current draw of my iPad Air (Air 1 in this case) to increase as the voltage is increased up to and including 5.3 V I have empirically shown that it behooves to charge at said voltage, assuming of course that the increase in current is actually an increase in battery charging current. This is the only assumption in the equation and I have no reason to believe otherwise. That is, I cannot believe that the charging circuit in the device which already intelligently controls the amount of current that the device draws would draw more current at slightly higher voltages only to dissipate it as heat.

Having said that, it is foolish to think that a tiny little device the size of the Apple charger and costing $2 to build can perform on the level of a $10,000 Laboratory Power Supply with voltage sense wires for proper load regulation (not to mention my more dubious, for purposes of this discussion (i.e., charging time), statement regarding ripple characteristics). Don't get me wrong, I am not saying I want to spend $10k on the power supply, my budget was $300.

Also, after setting a limit for myself of $300 for the power supply, I am going to spend $25 (less than 10% of the amount I budgeted) as I have stated in a previous reply, a cost that is not that much more than the Apple charger. Of course there will be additional parts, but those will be (even in sum) relatively cheap in comparison. Additionally, the power supply will be able to charge two devices concurrently at max charging current. This would require a $19+$19=$38+Tax=$41 investment from Apple.

Why am I only spending $25 on the power supply when I budgeted $300? Well that's the most interesting question at the current state of the project, but then nobody made any recommendations for power supplies on the forum, so I was kind of on my own here.

I am still curious as to whether I made a good decision on the power supply and am open to hearing recommendations to compare and contrast with my choice (costing up to and including $1,000).

[SharpEars]

Get a phone with easily interchangable batteries + a spare battery then hack a camera battery charger to match the terminals on the phone battery.   Charging the phone now takes under a minute!   

Incidentally,I suggest editing the topic title to "Sick of Apple?".  If you don't like the behaviour/performance, don't buy the kit! 

Good LiPO batteries can reach 250Wh/Kg.  Current Supercapacitors reach 30Wh/Kg. so an 'instant' charging phone would have to be much bigger.  Also high current circuits need more copper, bigger caps, more ferrite in inductor cores, more silicon area and of course far more geatsinking so there wold be a knock-on effect on the size of the rest of the phone.   If you have the funding to commission the design from any leading phone manufacturer, an 'instant' charging phone could be on the market by Christmas, but it would be the size and weight of half a house brick and would need direct connection to a car battery's terminals  for 15 seconds to charge it! 

I'm fine with the kit sans the charger(s). It is not an all or nothing proposition - there are multiple pieces in play (i.e., the device, the cord and the wall charger).
Also, back at reality ranch, , I am just looking for a slight reduction in charging time on the order of 6-8% here, not miracles. So, I don't see why there is all this negativity .

[Jeroen3]

I'd assume Apple incorporated advanced battery controls. Because when I had the battery of my iPhone 3gs replaced it completely fooled around with the remaining %.  Shutting of at 30 and not charging to 100.
Somewhere some set of parameters would need a reset. I would be interested to know how many mAh's go into the iphone. Someone able to measure that?
You can charge the iPhone turned off by inserting the charger before switching off.

The actual cable of Apple also performs some power quality checking. The two chips in there are not only for cable DRM.

[Melt-O-Tronic]

It would be pretty simple to set up your lab power supply to meet the specs of your "SupperCharger+" idea.  Log the data and compare to a charge with one of the devices that upsets you.  Just make sure you have the same starting state-of-charge for each test.

Then you'll know whether you have a viable concept.

[SharpEars]

It would be pretty simple to set up your lab power supply to meet the specs of your "SupperCharger+" idea.  Log the data and compare to a charge with one of the devices that upsets you.  Just make sure you have the same starting state-of-charge for each test.

Then you'll know whether you have a viable concept.

I think an even better test would be to time a 0-100% charge, first with the 12W wall charger and then with a well regulated 5.3 V supply (with the USB D+/D- pins fixed at 2.7 V to make the device think it is being charged from a 12W wall charger).

[Melt-O-Tronic]

Is there an echo in here?   

[JacquesBBB]

This is my power supply for USB charging.

It has 4 outputs
Voltmeter,
Ammeter
switch

It is a reconditioned Sunray light terminal from the dumpster. I shorted a resistor to get 5.20 V instead of 5.00V
All parts, except  the meters come from the board itself.
It is well regulated.
I put a small daughter board to get the proper voltage on D+ and D- to get  2A charging mode on Apple stuff.
As it is, it is charging an IPAD 2, A Galaxy note,  another  android device, and a charging bank.

[suicidaleggroll]

Also, in answer to this having a detrimental affect on the battery being charged, it's all within spec, the USB 3.0 spec (max VBUS voltage is 5.3 V), so Apple has to have allowed for this and I will be just taking advantage of it.

What makes you think that just because the manufacturer allows it to function in that condition, that it's not ultimately detrimental or harmful to the product?  There are a TON of things you can do to a phone that will damage it, that the manufacturer doesn't explicitly block.  Compensating for a voltage drop in the cable is one thing, but purposely over-driving the input to try to trick the phone into charging faster than it's designed for it just dumb.

Have you even bothered to think about why they limit the maximum charging current?  Hint: it's not to piss you off.  I can practically guarantee you that if the marketing department didn't have a say in the matter, the engineers designing the phone would have limited the charging current even more than they already have to give the battery a longer lifetime.

I for one don't want a faster charger.  I don't even like charging my phone at the normal max charging current.  I'll do it if I have to, but most of the time I'm not in a rush, so I'll use a 500mA port on a computer to give it a nice slow charge.  I'm all for faster charging, but only after battery technology has improved enough to allow it without long term damage.

[JacquesBBB]

You will not  decrease the charging time by increasing the voltage of the  USB port.
The battery is not charged with the USB voltage. There is a regulator  between the USB port and the battery.
There is no way you can change the regulator behavior.

On the other hand, I noticed that if you are slightly below 5.0 V,  it will use much more amps from the PSU,
probably  get at the end the same power. This is why i preferred to be a little bit above 5V than below 5V,
It allows to  charge more devices from the same source, but  I  do not think it will charge faster any of the devices.


Edit :This is wrong.  See below.

[SharpEars]

This is my power supply for USB charging.

It has 4 outputs
Voltmeter,
Ammeter
switch

It is a reconditioned Sunray light terminal from the dumpster. I shorted a resistor to get 5.20 V instead of 5.00V
All parts, except  the meters come from the board itself.
It is well regulated.
I put a small daughter board to get the proper voltage on D+ and D- to get  2A charging mode on Apple stuff.
As it is, it is charging an IPAD 2, A Galaxy note,  another  android device, and a charging bank.

image omitted...

Now here is a kindred spirit! I tried doing the same thing with an old ATX power supply, but the power regulation was horrible. It started out at something like 5.76V and then dropped below 5V with the slightest load - complete crap. This also made creating a constant 2.7 V for the D+/D- via a ladder divider impossible.

How did you manage to get D+/D- at 2.7 V independent of the supply voltage? Or, did you tweak them for the 5.2 V output?

[SharpEars]

You will not  decrease the charging time by increasing the voltage of the  USB port.
The battery is not charged with the USB voltage. There is a regulator  between the USB port and the battery.
There is no way you can change the regulator behavior.

On the other hand, I noticed that if you are slightly below 5.0 V,  it will use much more amps from the PSU,
probably  get at the end the same power. This is why i preferred to be a little bit above 5V than below 5V,
It allows to  charge more devices from the same source, but  I  do not think it will charge faster any of the devices.

Then explain why the current load increases as the voltage increases up to the OVP? If what you are saying is true, the current load on the PS should decrease with increasing voltage.

I understand that there is an intelligent regulator between the lightning cable connector and the batteries. However, it seems to me that it is supplying more current to the battery as the voltage increases up to the OVP. It is either that or it is sinking the excess current and converting it to heat, which I find unlikely but possible.

[JacquesBBB]

In fact,  I was wrong.

After writing the above lines, I checked (rapidly ) on my PSU with   a small  board with voltege dividers before the USB plus
with the ipad 2, I got (it is already 89% full)

4.7 V  : 0.88 A
4.8 V  : 1.07 A
4.9 V  : 1.18 A
5.0 V  : 1.3   A
5.1 V  :  1.51 A
5.2 V  : 1.55 A

Note that this was not the best conditions as  it would have been more regular with a nearly  empty device (at least not nearly full).

[JacquesBBB]

Now here is a kindred spirit! I tried doing the same thing with an old ATX power supply, but the power regulation was horrible. It started out at something like 5.76V and then dropped below 5V with the slightest load - complete crap. This also made creating a constant 2.7 V for the D+/D- via a ladder divider impossible.
How did you manage to get D+/D- at 2.7 V independent of the supply voltage? Or, did you tweak them for the 5.2 V output?

In my case, the voltage is 5.2 V at zero load and 5.18 at  4 A.   This is not an ATX PSU. It is made to deliver only 5V.
So the D+/D- voltage should not vary much.
 

[SharpEars]

In fact,  I was wrong.

After writing the above lines, I checked (rapidly ) on my PSU with   a small  board with voltege dividers before the USB plus
with the ipad 2, I got (it is already 89% full)

4.7 V  : 0.88 A
4.8 V  : 1.07 A
4.9 V  : 1.18 A
5.0 V  : 1.3   A
5.1 V  :  1.51 A
5.2 V  : 1.55 A

Note that this was not the best conditions as  it would have been more regular with a nearly  empty device (at least not nearly full).

Thank you for confirming my findings and I assume we are now in agreement?

[SharpEars]

Now here is a kindred spirit! I tried doing the same thing with an old ATX power supply, but the power regulation was horrible. It started out at something like 5.76V and then dropped below 5V with the slightest load - complete crap. This also made creating a constant 2.7 V for the D+/D- via a ladder divider impossible.
How did you manage to get D+/D- at 2.7 V independent of the supply voltage? Or, did you tweak them for the 5.2 V output?

In my case, the voltage is 5.2 V at zero load and 5.18 at  4 A.   This is not an ATX PSU. It is made to deliver only 5V.
So the D+/D- voltage should not vary much.

OK, so it is much better at load regulation (only a 20 mV drop at a 4 A load) and therefore you were OK with a simple resistor ladder V divider to get the 2.7 V? Or how did you do this with the daughter card?

[JacquesBBB]

The 2.7  were just obtained with voltage dividers with 2 resistors.

[JacquesBBB]

This was from a previous design, without the meters.
I must say it is much better with the meters.

[SharpEars]

This was from a previous design, without the meters.
I must say it is much better with the meters.

Nice! Really nice! Is that all just power supply circuity or is there other circuitry mixed in?

Oh, I see... You separated the tan power supply board from the computer and added the daughter card.

So, what's the current limit on this thing? If I connect four iPads to it, will it put out 8+ Amps?

[JacquesBBB]

Oh, I see... You separated the tan power supply board from the computer and added the daughter card.

So, what's the current limit on this thing? If I connect four iPads to it, will it put out 8+ Amps?

I have not push it to its limits,  but I believe its about 5A. I had never any limitations with the 4 outputs,
and I believe there is an internal protection as well,  but I  did not experimented with it.

[JacquesBBB]

Oh, I see... You separated the tan power supply board from the computer and added the daughter card.

Quite nicely, I retrieved the daughter board connector and the USB plugs from the main board.

[SharpEars]

The 2.7  were just obtained with voltage dividers with 2 resistors.

I've decided to use LM317 for the fixed USB data voltages (so I am going to mount at least two of them for 2.3 V and 2.7 V, respectively, allowing for compatibility with all Apple and many Android devices). I can use the output of the 2.7 V going to both D+ and D- for Apple devices. I can use a mixture of 2.3V and 2.7V for Android devices, depending on the charging level they support. I will mount dip switches to control the voltage that goes each of the four (because there are two USB ports) Data pins.

[SharpEars]

Oh, I see... You separated the tan power supply board from the computer and added the daughter card.

So, what's the current limit on this thing? If I connect four iPads to it, will it put out 8+ Amps?

I have not push it to its limits,  but I believe its about 5A. I had never any limitations with the 4 outputs,
and I believe there is an internal protection as well,  but I  did not experimented with it.

I am surprised that it has such good load regulation, because the PS circuit looks very, well, simplistic. Do you (or anyone else on the forum) know if it's a linear or switching circuit? I can't quite tell just by glancing at its pic from the top.

[JacquesBBB]

Its a switching power supply.

The file attached is an attempt to reverse enginer  the regulator part of the PSU.
I could then modify the voltage by changing R49.
As initially it was a little bit below 5V.  I shorted it to put it at 5.2V, but now, I am more thinking of
putting the voltage to 5.1 V . Maybe I should  put some switch or pot  to leave the possibility of
slight changes in the voltage.

[SharpEars]

Its a switching power supply.

The file attached is an attempt to reverse enginer  the regulator part of the PSU.
I could then modify the voltage by changing R49.
As initially it was a little bit below 5V.  I shorted it to put it at 5.2V, but now, I am more thinking of
putting the voltage to 5.1 V . Maybe I should  put some switch or pot  to leave the possibility of
slight changes in the voltage.

If there's anything I decided on up front it's to allow for voltage trim. So, I would definitely agree with your premise of adding a pot to be able to adjust the voltage. The downside is that I will have to use voltage regulators for the Data pin voltages instead of resistor ladders.

[JacquesBBB]

In fact, it is a samsung AD-3005 PSU  30W (6A).

The switching  component is a TOP247Y
https://www.westfloridacomponents.com/mm5/graphics/H02/TOP250YN-Power-Integrations.pdf

Compared to  an apple PSU,  it is much less cramped in a small place; Of course, it  is not portable,
but  the heat dissipation is much more efficient.
For my desk use, it is perfect. The improvement that could be done would be a way to shut it down completely in case of no load.
This would be some next project.
 

[SharpEars]

In fact, it is a samsung AD-3005 PSU  30W (6A).

The switching  component is a TOP247Y
https://www.westfloridacomponents.com/mm5/graphics/H02/TOP250YN-Power-Integrations.pdf

Compared to  an apple PSU,  it is much less cramped in a small place; Of course, it  is not portable,
but  the heat dissipation is much more efficient.
For my desk use, it is perfect. The improvement that could be done would be a way to shut it down completely in case of no load.
This would be some next project.

A guy in the UK is selling it used for $46.75 on eBay at the moment with unspecified shipping charges. I spent less than $25 on my power supply (all in including shipping, which accounted for almost a third of the price), which I will reveal this weekend. For now, I will say that it is also capable of sourcing at least 6A and that it is not one of these pieces of s..t being sold on eBay:


One shortcoming of that Samsung supply is that it lacks voltage sense capability and a voltage trim (without mods). A tried to find a spec sheet PDF for it, but I couldn't find it.

[JacquesBBB]

I dont say that  this is the best PSU, or that I would  buy it  at the price it is on the net.
I got a bunch of them for free, before they went to the trash.
I realized that they were very decent PSU for USB power, and found a way to reuse the original
case without too much work.

I could not find the schematics, but I am now getting familiar with them, and can consider making some
modifications,  although I still need to finish  one or two more in order to fill my needs.

[SharpEars]

I dont say that  this is the best PSU, or that I would  buy it  at the price it is on the net.
I got a bunch of them for free, before they went to the trash.
I realized that they were very decent PSU for USB power, and found a way to reuse the original
case without too much work.

I could not find the schematics, but I am now getting familiar with them, and can consider making some
modifications,  although I still need to finish  one or two more in order to fill my needs.

I do agree, you can't beat free.

[Monkeh]

I dont say that  this is the best PSU, or that I would  buy it  at the price it is on the net.
I got a bunch of them for free, before they went to the trash.
I realized that they were very decent PSU for USB power, and found a way to reuse the original
case without too much work.

I could not find the schematics, but I am now getting familiar with them, and can consider making some
modifications,  although I still need to finish  one or two more in order to fill my needs.

I do agree, you can't beat free.

You got a free charger with all your devices. Why do you keep trying to beat it?

[JacquesBBB]

You got a free charger with all your devices. Why do you keep trying to beat it?

Very simple,
1) I do not want to move the chargers with the devices.
2) with a 4 ports  USB PSU, I need only one plug.
3)  I had several of the original chargers who failed after some time.
4) Some chargers are 0.5 A, other 1 A others (not so many)  2 A,  so  they are not interchangeable,
while you can plug anything in a more powerful PSU, it will always charge at maximum possible speed.
5) Some devices do not come with chargers, as the power bank which I bought on ebay.

[amyk]

You're assuming that with a voltage of 5V at the charger, the phone is actually limited by that CC current. I dare say that's a completely unfounded assumption (and seemingly disproved by the OP's assertion that the current does increase) -- phones compliant with standard X (I forget the name) will look for voltage sag from the charger as an indication that the charger is at its limit, and will be current limited by the charger instead, i.e. charging current = min(LiPo CC, charger capability).

LiPo batteries have very low internal resistance, hence why they need current-limited charging. Any difference between Vbat and Vbus will be dissipated as heat in a linear charger. Assuming a battery that stays around 3.8-4V during most of its charge cycle, and LDO-type current regulator with a dropout voltage of ~1V, then a 5V input would be enough.

Even if the adapter is supplying 5V, the cable and contact resistance reduces this, which is why they're adjusted to 5.3V no load - the extra 0.3V is to compensate for resistive losses in the path so ~5V ultimately ends up at the current regulator. In light of this, you'll probably be charging as fast as possible if you just use 5V with remote sense at the Lightning connector's Vcc.

(Of course this is assuming they don't do something funky like increase the CC based on input voltage, which being Apple, wouldn't surprise me. But based on the numbers posted so far, it's just plain resistive losses you're fighting against.)

FWIW the USB forum recently (August 2014) increased the maximum official Vbus to 5.5V, likely because most if not all existing devices were fine with 5.5V anyway and this gives a wider 10% tolerance.

[rs20]

LiPo batteries have very low internal resistance, hence why they need current-limited charging. Any difference between Vbat and Vbus will be dissipated as heat in a linear charger. Assuming a battery that stays around 3.8-4V during most of its charge cycle, and LDO-type current regulator with a dropout voltage of ~1V, then a 5V input would be enough.

Even if the adapter is supplying 5V, the cable and contact resistance reduces this, which is why they're adjusted to 5.3V no load - the extra 0.3V is to compensate for resistive losses in the path so ~5V ultimately ends up at the current regulator. In light of this, you'll probably be charging as fast as possible if you just use 5V with remote sense at the Lightning connector's Vcc.

(Of course this is assuming they don't do something funky like increase the CC based on input voltage, which being Apple, wouldn't surprise me. But based on the numbers posted so far, it's just plain resistive losses you're fighting against.)

FWIW the USB forum recently (August 2014) increased the maximum official Vbus to 5.5V, likely because most if not all existing devices were fine with 5.5V anyway and this gives a wider 10% tolerance.

Agreed on all points -- but the end conclusion is that a charger that can hold up 5.3V at 2A is faster charging that sags to 5V at 2A, right? Because the latter would starting eating into the voltage budget at the phone once you factor in cable losses. Regardless, JacquesBBB's figures demonstrate this; the current going into the phone increases rapidly up to 5.1V, before tailing off at 5.2V. So charger delivering, say, 5.15V + loop losses for 1.5A, at 1.5A is ideal there, and it seems bold to claim that any randomly chosen charger will achieve this.

To clarify my point, I of course agree that going arbitrarily high on voltage is obviously pointless, at some point you just start burning up more in the linear reg. What's not so clear is whether your typical phone plugged into your typical charger is actually operating in that regime.

[JacquesBBB]

I have measured the output of my genuine 10 W  Apple Ipad charger 

I found
   
         0 A           1.6A

V+ : 5.15 V       5.02 V
D+ : 2.76 V       2.70 V
D-  : 2.06 V       2.02 V

So the difference with my PSU is not the voltage at no load, but the fact that  it is much better regulated.

[Richard Crowley]

So the difference with my PSU is not the voltage at no load, but the fact that  it is much better regulated.

Please remind us why that is important?
Considering that the built-in charging circuit does the ACTUAL CURRENT REGULATION and cares nothing about the incoming voltage.

[rs20]

So the difference with my PSU is not the voltage at no load, but the fact that  it is much better regulated.

Please remind us why that is important?
Considering that the built-in charging circuit does the ACTUAL CURRENT REGULATION and cares nothing about the incoming voltage.

A fact that is proven false by the numbers posted by JacquesBBB a few pages ago (current rising as voltage rises). Evidently the in-phone regulator is not getting sufficient voltage if the supply voltage sags much near/below 5V.

[Siwastaja]

It makes a lot of sense to limit charging current if the supply voltage sags below 5V, so charging current control based on input voltage has long been reality in laptops, and why not phones, too. It's not very surprising that this principle extends to a bit over 5.0V, too.

It is true that higher current charging does more damage to the battery (via lithium plating), but it's not a simple equation at all. And I understand that some people might want quicker charging, even if they needed to replace the battery more often. But don't try to do it when the battery is cold. Cooling the battery too much may be detrimental. Optimum cell temperature for quick charging might well be around 40-45 deg C.

Quick charge damage can happen in a surprising way; the cell may work fine for 50 cycles, then degrade quickly over the next 20.

Most of the quick-charging damage is done at high state of charge (over 4.0 volts), so if you only charge your phone to approx. 70%, probably no extra damage is done, even if the current was 20-30% higher than normal. Very quick charging requires an additional current curve in addition to CC-CV, as too much damage is done near the CV voltage at high rates. For example, a cell can be fine up to 1.5C charge until 3.9V, then linearly derating to 0.5C until 4.2V, then CV.

[SharpEars]

I dont say that  this is the best PSU, or that I would  buy it  at the price it is on the net.
I got a bunch of them for free, before they went to the trash.
I realized that they were very decent PSU for USB power, and found a way to reuse the original
case without too much work.

I could not find the schematics, but I am now getting familiar with them, and can consider making some
modifications,  although I still need to finish  one or two more in order to fill my needs.

I do agree, you can't beat free.

You got a free charger with all your devices. Why do you keep trying to beat it?

Because you get a 1 A charger with phones (even though some can charge at 2 A) and a 2 A charger with tablets. Apple tries to sell you a so called 2.4 A charger for $19 (even though in reality it charges iPads at only 1.8 A). I want something that charges at MAX A, within the device's safety parameters. This MAX A will always be more than any Apple (or other) charger will supply, because it will be caused by charging at the highest reasonable (and safe) voltage before the device OVP kicks in.

[SharpEars]

You're assuming that with a voltage of 5V at the charger, the phone is actually limited by that CC current. I dare say that's a completely unfounded assumption (and seemingly disproved by the OP's assertion that the current does increase) -- phones compliant with standard X (I forget the name) will look for voltage sag from the charger as an indication that the charger is at its limit, and will be current limited by the charger instead, i.e. charging current = min(LiPo CC, charger capability).

LiPo batteries have very low internal resistance, hence why they need current-limited charging. Any difference between Vbat and Vbus will be dissipated as heat in a linear charger. Assuming a battery that stays around 3.8-4V during most of its charge cycle, and LDO-type current regulator with a dropout voltage of ~1V, then a 5V input would be enough.

Even if the adapter is supplying 5V, the cable and contact resistance reduces this, which is why they're adjusted to 5.3V no load - the extra 0.3V is to compensate for resistive losses in the path so ~5V ultimately ends up at the current regulator. In light of this, you'll probably be charging as fast as possible if you just use 5V with remote sense at the Lightning connector's Vcc.

It is nearly impossible to build a device that can remote sense at the Lightning connector's V_cc. This is one of the challenges I will be facing.

(Of course this is assuming they don't do something funky like increase the CC based on input voltage, which being Apple, wouldn't surprise me. But based on the numbers posted so far, it's just plain resistive losses you're fighting against.)

But, my claim is that this is exactly what they are doing, increasing current as the voltage increases up to the OVP.

FWIW the USB forum recently (August 2014) increased the maximum official Vbus to 5.5V, likely because most if not all existing devices were fine with 5.5V anyway and this gives a wider 10% tolerance.

Awesome, so if I can get 5.5V into the device, I would charge it even faster and no wall wart (5 V) charger puts out 5.5 V.

[SharpEars]

I have measured the output of my genuine 10 W  Apple Ipad charger 

I found
   
         0 A           1.6A

V+ : 5.15 V       5.02 V
D+ : 2.76 V       2.70 V
D-  : 2.06 V       2.02 V

So the difference with my PSU is not the voltage at no load, but the fact that  it is much better regulated.

The 12 W charger does not do much better, maxing out at (IIRC) 1.8 A at (from memory):

        1.8A

V+:  5.06V - 5.08V (at load)
D+:  2.75V (Note: 2.75 D+/2.75 D- is the 12 W charger indicator config)
D- :  2.75V

[SharpEars]

So the difference with my PSU is not the voltage at no load, but the fact that  it is much better regulated.

Please remind us why that is important?
Considering that the built-in charging circuit does the ACTUAL CURRENT REGULATION and cares nothing about the incoming voltage.

So you mean to say that the built-in charging circuit, rather than intelligently reducing the current load as voltage increases to maintain a constant output voltage (and current), burns it off instead (e.g., like a Zener)?

[eas]

I got tired of reading the idle speculation, so apologies if I missed this, but I went digging through teardowns and checking part numbers last year because I wondered about Apple's choice of charge controller. From that research, I learned that it looks very much like Apple iPhone and iPads made in the last 3+ years use switch-mode chargers.

My own idle speculation is that they use switch-mode charge regulators in service of speeding charging time. With switch mode regulators, they can devote more of the thermal budget to heating due to battery internal resistance, giving them more headroom to use higher charging currents.

I also speculate, based on anecdotal observation of charging currents on my iDevices, that Apple is not using the standard two-phase CC/CV charging algorithm. I haven't collected datapoint through a whole charging cycle though.

The thing about Apple products, which inspires both their admirers and haters, is that they are designed as full system that actually extends across multiple devices over the lifetime of the user. From this perspective, one conclusion I reach is that there isn't going to be a lot of headroom for you to improve charging speed over what you see with Apple's cable's and power supplies, not without tweaking firmware and potentially internal components.

That said, I'm interested to see how you do. I bet there is 10-15% in there somewhere, though probably the cheapest way to get there is with a fat power leads to a short lightning cable, or if you want something a little more fun and elegant, sense leads the splice points on a short lightning cable.

A few more, thoughts:

• "Clean" power matters to the extent that too much noise can wreak havoc with capacitive touch sensors if you are using the device while charging.
• Some quick-chargers, like the multi-port Anker I have, step up the delivered voltage as current rises. I assume this is done to compensate for resistive losses in the USB cable at higher currents. I think this may actually be a features of some USB fast-charge ICs from TI or similar.
• I think that with the iPhone 6, and the wall-warts that shipped with it, Apple may have moved away from their proprietary charger sensing to just taking as much juice as they needed or until voltage drops too much.

[Siwastaja]

Awesome, so if I can get 5.5V into the device, I would charge it even faster and no wall wart (5 V) charger puts out 5.5 V.

That may be a wrong conclusion, however - nothing physical nor any sane design principle dictates that kind of behavior.

You have experimentally found that the charge controllers you tested do indeed increase charging current with 5.3V supply compared to 5.0V supply, but the expectation that it would go on still beyond 5.3V is unfounded. Going too far, however, will increase heat losses in devices that utilize linear charge controllers, and at some point, they may start thermal limiting. There will be a sweet spot, and you may have found it at 5.3V. In any case, it will be highly device-dependent and the only way to know is to actually test as you have  done.

Do the modern iDevices with high charging currents really use linear controllers? Anyone? If you think about charging an empty cell (3.5V) at 2A from a 5.0V supply, it would be 3W loss in charge controller only - the heat sinking would make it bigger than a comparable buck converter. If it's really a DC/DC, then the actual charging current increases even more than the OP has measured. Edit: eas has confirmed (above) the use of a switch mode controller, as you would expect.

[IanB]

I do not find any issue with the standard Apple chargers. My devices run for days between charges meaning I don't normally have to charge them in a hurry. When the battery gets down to about 30% I just plug them in overnight and they are ready by the morning. That said, if I do charge them during the day it only takes about 2 hours to get most of a full charge. Also, the times when you do want a super fast charge (like sitting in an airport lounge waiting for a plane) you are not likely to have your super charger in your hand baggage...

[JacquesBBB]

The 12 W charger does not do much better, maxing out at (IIRC) 1.8 A at (from memory):

        1.8A

V+:  5.06V - 5.08V (at load)
D+:  2.75V (Note: 2.75 D+/2.75 D- is the 12 W charger indicator config)
D- :  2.75V

Are you sure ?

I just made an additional test, by using pots at D- and D+, and  for  D- = 2.75 V current remains below 1 A.

This is also what can be found  here
http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html

with a lot of additional information on this topic.

[JacquesBBB]

I do not find any issue with the standard Apple chargers. My devices run for days between charges meaning I don't normally have to charge them in a hurry. When the battery gets down to about 30% I just plug them in overnight and they are ready by the morning. That said, if I do charge them during the day it only takes about 2 hours to get most of a full charge. Also, the times when you do want a super fast charge (like sitting in an airport lounge waiting for a plane) you are not likely to have your super charger in your hand baggage...

By the way,  I participate to this discussion because I   have interest in building USB  PSU that is adapted to  Apple devices, but I have not much problems with the USB  PSU of  Apple and  I had no failures on Apple Ipad PSU.
I do not think the  self made PSU  could be a large gain  with respect to the original from Apple.

I have solved  the problem of fast charge  (when I need to go and realize that my ipad is empty). I have a
power bank containing 4  18650 batteries that  can provide 2 A and charge a full ipad.
So if I need to go,  I just hook the ipad to the powerbank and put both in my bag.

Nevertheless, I must say  that  I just checked  the output of a  10W ipad  charger, and had 1.4 A, while I had 1.95 A on my PSU when set to 5.2V. So there is place for small improvement.

I am much more reserved on the  Apple PSU for  macbook Pro. I have experienced many failures with those. Moreover, there are not easy to repair. but I would not make a PSU for macbook pro as I have not yet understood  the way the magnetic connector works. That would be another story ...

[IanB]

I have solved  the problem of fast charge  (when I need to go and realize that my ipad is empty). I have a
power bank containing 4  18650 batteries that  can provide 2 A and charge a full ipad.
So if I need to go,  I just hook the ipad to the powerbank and put both in my bag.

There is a risk that power bank could be confiscated by airport security (due to lithium battery air transport regulations).

[amyk]

Most of the quick-charging damage is done at high state of charge (over 4.0 volts), so if you only charge your phone to approx. 70%, probably no extra damage is done, even if the current was 20-30% higher than normal. Very quick charging requires an additional current curve in addition to CC-CV, as too much damage is done near the CV voltage at high rates. For example, a cell can be fine up to 1.5C charge until 3.9V, then linearly derating to 0.5C until 4.2V, then CV.

Perhaps a simple 4.2V supply and current-limiting resistor would actually give the most "gentle" charge? The curent would be proportional to the charge voltage, being the highest at low charge and then tapering off gradually as it approaches 4.2.

It is nearly impossible to build a device that can remote sense at the Lightning connector's Vcc. This is one of the challenges I will be facing.

Hack apart a connector (carefully!) and solder a sense wire to the Vcc pin. You can also buy raw connectors and breakout boards from various Chinese shops - see this page for some more interesting details:

http://ramtin-amin.fr/tristar.html

I got tired of reading the idle speculation, so apologies if I missed this, but I went digging through teardowns and checking part numbers last year because I wondered about Apple's choice of charge controller. From that research, I learned that it looks very much like Apple iPhone and iPads made in the last 3+ years use switch-mode chargers.

Do you have any part numbers to show? The numbers posted above suggest that the current flattens off at around 5.1-5.2V (where is this measured?)

[Richard Crowley]

So you mean to say that the built-in charging circuit, rather than intelligently reducing the current load as voltage increases to maintain a constant output voltage (and current), burns it off instead (e.g., like a Zener)?

Your question is flawed.
Yes, the built-in charging circuit DOES "intelligently reduce the current load as voltage increases to maintain a constant output voltage (and current)." The reason for this is to protect the battery cells to prevent overheating, fire and explosion. And to comply with the ideal charging profile for whatever chemistry of the cells under charge.

As for HOW it regulates, yes SOME charger circuits probably use analog pass elements which dissipate the unwanted power as heat.  And likely more modern gadgets use switch-mode regulation (which, BTW, care even LESS how "regulated" their raw input power is since they literally make a "hash" of it.)  Those are the ONLY two ways of accomplishing power regulation that I am aware of. If there are others, I'm sure someone will remind us.

[SharpEars]

The 12 W charger does not do much better, maxing out at (IIRC) 1.8 A at (from memory):

        1.8A

V+:  5.06V - 5.08V (at load)
D+:  2.75V (Note: 2.75 D+/2.75 D- is the 12 W charger indicator config)
D- :  2.75V

Are you sure ?

I just made an additional test, by using pots at D- and D+, and  for  D- = 2.75 V current remains below 1 A.

This is also what can be found  here
http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html

with a lot of additional information on this topic.

What device are you testing? If you it's an iPhone 5s or lower, then the most you're going to pull from 5 V is 1 A. If it's a device that is capable of charging at a higher current (e.g., an iPad that can take on 2A) then the reason lies in the D+/D- lines not staying above 2.7 V when the the (relatively small) load is placed on them by the device being charged, as part of determining the type of charger you are using. You can try using smaller resistors for your ladder (in the tens of kOhms) and see if that makes a difference.

Also, for my testing I not only set the D+/D- lines to 2.7 V, but I short them together as well. That is, I create a ladder divider using a single pot to produce the 2.7 V and then I connect both data pins to that output. This may be the difference between my test and yours. The link you provided comparing various chargers does not mention the Apple 12 W charger or its configuration, but I was able to find this on "some Chinese web site" and confirm it via a TI spec page for one of the new ICs they are producing for use in 12 W universal chargers.

[SharpEars]

So you mean to say that the built-in charging circuit, rather than intelligently reducing the current load as voltage increases to maintain a constant output voltage (and current), burns it off instead (e.g., like a Zener)?

Your question is flawed.
Yes, the built-in charging circuit DOES "intelligently reduce the current load as voltage increases to maintain a constant output voltage (and current)." The reason for this is to protect the battery cells to prevent overheating, fire and explosion. And to comply with the ideal charging profile for whatever chemistry of the cells under charge.

As for HOW it regulates, yes SOME charger circuits probably use analog pass elements which dissipate the unwanted power as heat.  And likely more modern gadgets use switch-mode regulation (which, BTW, care even LESS how "regulated" their raw input power is since they literally make a "hash" of it.)  Those are the ONLY two ways of accomplishing power regulation that I am aware of. If there are others, I'm sure someone will remind us.

So, given that the iDevices use the latter form of circuit (i.e., switch mode regulation) as several people here already pointed out, it would make sense for the current draw to decrease as the incoming voltage increases. It does the exact opposite (i.e., the current the device draws increases with voltage until the OVP kicks in).

[Richard Crowley]

So, given that the iDevices use the latter form of circuit (i.e., switch mode regulation) as several people here already pointed out, it would make sense for the current draw to decrease as the incoming voltage increases. It does the exact opposite (i.e., the current the device draws increases with voltage until the OVP kicks in).

Wrong question again.  The current doesn't increase or decrease based in the INCOMING power.  The current is regulated by the charging profile for the particular battery being charged.  It is a much more complex process than you seem to be imagining.  It is based on the beginning state of the charge, the temperature, how fast the battery is accepting the charge, etc. etc. etc.  And in many cases there is a microprocessor inside the battery pack which keep tracks of the previous discharge cycle to further optimize the latest charge cycle.

And it has almost nothing to do with the source power available. Except that it clearly can't put MORE current into the battery than is available from the source. Which is why some devices complain of "slow charge" when they can't get as much power from the source as they want.

[SharpEars]

So, given that the iDevices use the latter form of circuit (i.e., switch mode regulation) as several people here already pointed out, it would make sense for the current draw to decrease as the incoming voltage increases. It does the exact opposite (i.e., the current the device draws increases with voltage until the OVP kicks in).

Wrong question again.  The current doesn't increase or decrease based in the INCOMING power.  The current is regulated by the charging profile for the particular battery being charged.  It is a much more complex process than you seem to be imagining.  It is based on the beginning state of the charge, the temperature, how fast the battery is accepting the charge, etc. etc. etc.  And in many cases there is a microprocessor inside the battery pack which keep tracks of the previous discharge cycle to further optimize the latest charge cycle.

And it has almost nothing to do with the source power available. Except that it clearly can't put MORE current into the battery than is available from the source. Which is why some devices complain of "slow charge" when they can't get as much power from the source as they want.

Wrong answer again. There is more current going into the device as the voltage increases (up to a point). This means that there is more INCOMING power. Now this has to be transferred to the battery (1) or given off as heat by either the device's regulation circuit or the battery's own protection circuit which ultimately includes the battery's cells themselves (2). Which one of these two possibilities are you asserting, because it has to be one of them or perhaps a combination of both? Are you suggesting that the extra incoming power is 100% being converted to heat and not being used to charge the battery's cells? This is what it sounds like you are suggesting, despite concurrently stating that the entire thing is microprocessor controlled. This of course makes no sense, because if it was truly microprocessor controlled, the incoming current would be reduced as the input voltage increases. It seems to me that whatever is inside these iDevices is far more simple. My claim is that some of the incoming excess power at raised input voltages is not only going to the battery but is actually being used to charge the cells within the battery (i.e., this includes getting through any circuitry in the battery and eventually hitting the battery's cells). I am not saying that 100% of the increase in power is getting to the cells, but I am saying that a very significant percentage of it is.

Without actual objective testing, both of us are speculating (i.e., theory crafting) and either of us could be right or we can both be partially right (i.e., some power is given off as heat and some is used to charge the cells).

So, the real test will be whether or not the battery will charge faster when it is charged from 0% until the charging circuit stops charging it any further (either the device's, the battery's or as is more likely the case, a combination of both). Also of interest will be the change in charging time as the voltage is increased from 5 V to 5.3 V. Of benefit would be thermal monitoring of the phone's case during both tests, but I do not have the equipment on hand to do this. I can however keep the environmental conditions relatively constant at least, so that external temperature does not skew the test.

The above is the test that I have not yet performed, because it takes several hours and requires a fully discharged device in combination with current draw tracking over the course of those hours to see how the charging circuit behaves and when the charge actually ends. I plan on perform this test in the near future with several devices to definitively answer the criticisms once and for all (and/or be proven wrong).

[Richard Crowley]

Will a cheap commodity charging circuit output more current when you supply more voltage into it than it was designed for?  Probably, when those circuits are designed down to the tenth of a cent.  Is that good for the battery you are trying to charge?  Probably not. In any case this whole discussion seems silly at best and dangerous at worst.

[Siwastaja]

Wrong question again.  The current doesn't increase or decrease based in the INCOMING power.

What are you trying to say? The actual input current draw has been experimentally measured by the OP and some others, and it's a result you can't just go and ignore --- and it's a fair assumption that the device is not a shunt regulator as it would be totally insane (a lot more insane than linear pass type regulator). I.e., power to cell = power in minus controller losses, which will be fairly consistent percentage for a switch mode regulator. More voltage AND more current in ---> DEFINITELY more current into the cell, unless the design is totally crazy (a shunt regulator).

The current is regulated by the charging profile for the particular battery being charged.  It is a much more complex process than you seem to be imagining.  It is based on the beginning state of the charge, the temperature, how fast the battery is accepting the charge, etc. etc. etc.  And in many cases there is a microprocessor inside the battery pack which keep tracks of the previous discharge cycle to further optimize the latest charge cycle.

I, as a battery management system designer, would tend to say that it's a lot more simple than you seem to be imaging. Although, industry has shown over-complex examples, which mostly tend to fail due to wrong assumptions made.

These iDevices do not have a battery pack, they have a single cell. Previous discharge cycle has absolutely nothing to do with any "optimization" of the charge cycle; you are just throwing in fancy weasel words; please stop, it belongs to kickstarer scams, not on this forum IMO. Thank you.

Li-ion is the simplest battery type in use so far; it has practically 100% (typically >99.9%) coulombic efficiency, practically no "memory effects", no Peukert effect. All losses are ohmic, i.e., voltage drops. It is always true that charge in = charge out. Lithium plating does limit allowable charging current especially at high voltages and low temperatures, but if the freaking device actually is measured taking in more charging power, then it's most definitely going into the cell. That may have two conclusions; they don't use 100% of their "allowed" charging current normally; or they are exceeding their "allowed" budget, causing more damage than it's designed for.

It is well possible that a mere 30% increase in charging current may shorten the lifetime of the cell from 500 to 100 cycles if it happens in just the right conditions, but it's not very probable they are so close to that limit.

[SharpEars]

I have decided to do a better test:

What is the charge percent on an iPhone 5 after charging for 20 mins. The start point is a dead phone (i.e., a phone that has shut off due to running low (i.i.e, below 1%) ). This is almost exactly the case for which I am designing.

That is:

• You have a dead or nearly dead phone
• You have a very short amount of time (say 5-20 mins), because you have to leave (plane, train or automobile) and you won't be packing a battery charger
• The actual test: To what percentage level can you charge your phone within that time as a function of charging voltage?

Take aways:

• You are most likely not charging your phone to 100%
• Your phone will start off but will turn on at some point, per Apple's OS/charger policy and you don't have the time/luxury to sit there and wait for that moment to manually turn it back off again

Results for iPhone 5 after twenty minutes of charging:

Charge voltage or charger	Charge percentage	Number of tests
5.0 V	13 %/13 %	2
5.3 V	13 %	1
Apple 12W charger	13 %	1

Therefore, for the iPhone 5 at a 20 min time and with the charging voltage as specified, there appears to be no difference between a charge at 5 V and a charge at 5.3 V. An Apple 12 W charger performs as well as a well regulated supply in terms of getting the phone's percentage up to 13 in twenty minutes. I want to do additional testing with different time periods and perhaps time the discharge time as well to do a crosscheck and further verify the results.

The two non-Apple power supply tests above were made using a HP 6632A 20 V/5 GPIB lab DC power supply (calibrated and traceable to NIST) set to the voltages specified. Power supply sense cables were used to maintain a constant voltage independent of load at the point of load. The power supply power cables were connected to a taken apart USB 2.0 female connector with about five centimeters of cables dangling. A lightning cable was attached to this connector with the lightning end plugged into the DUT, an iPhone 5. The current reading on the PS was monitored to make sure that the 2.7 V D+/D- setting had taken affect (i.e., we were charging at the max current supported by the DUT).

A calibrated Fluke 8506A (6 1/2 digit) multimeter was used to monitor the voltage which stayed constant for both tests and was 3 mV above the voltage stated in the above table for the duration of the test - an insignificant deviation. The reading was crosschecked with a calibrated HP 3456A (6 1/2 digit) multimeter which differed lower by 12 counts from the Fluke - again, an insignificant deviation for the purpose of this test.

I want to run further tests for the iPad as well. I think this is where there may be a difference and at this point I definitely want to do further testing before making any additional claims.

[Monkeh]

There is a cheaper, easier, smaller, and more effective solution to the problem your scenario presents. It is called a battery.

www.amazon.com/dp/B005X1Y7I2

*wanders off*

[amyk]

Also, I found it odd in discharging the phone that it stayed at 13% longer when charged at 5.3 V than at 5.0 V, so there maybe some mysterious activity here

Forget about those percentages if you want accurate results; you really need to measure the voltage and current into the cell together to determine the overall energy put in. Current will be harder to do since you'll need to insert a shunt inline, but voltage should be relatively easy.

Don't forget to account for the slight (but measurable) capacity loss every time you cycle the cell too...

[IanB]

...and you won't be packing a battery charger

WTF? 

Why not?

[funkathustra]

Results for iPhone 5:

Charge voltage	Charge percentage	Number of tests
5.0 V	13 %/13 %	2
5.3 V	13 %	1

Therefore, for the iPhone 5 at a 20 min time and with the charging voltage as specified, there appears to be no difference between a charge at 5 V and a charge at 5.3 V.

I'm glad it only took us 90 posts to realize that Apple probably knows how to design a USB power pack that will provide good charging performance.

An iPhone 6 has an 1800 mAh battery. Assuming Apple programmed the charger to charge at 1C (to extend battery lifetime), the charger will use up to 1800 mA of current. It's a switching regulator, so it could use appreciably less current from the USB VBUS to achieve that. For example, 4V @ 1800mA = 5V @ 1.4A (assuming 100% efficiency).

I'm in the camp that thinks if you want to charge your phone faster, you'll have to swap the battery charger IC in your phone, and then pay dearly for it in 6 months when your battery is shot. That's when you'll really need your SupperFast charger (is it supper time yet? I'm hungry).

The increased current consumption you see at higher voltages is strange, but is probably due to operating near the upper limits of the battery charger. I've seen very strange behavior out of ICs before -- in deep-sleep mode, an ESP8266 will use hundreds of times more power if you're running it at 3.6V instead of 3.3V, for example. I've never tested regulators, but I could imagine protection components or other things that would end up shunting the current to ground as voltage approached a threshold.

[Monkeh]

This increased current consumption is strange, but is probably due to operating near the upper limits of the battery charger. I've seen very strange behavior out of ICs before -- in deep-sleep mode, an ESP8266 will use hundreds of times more power if you're running it at 3.6V instead of 3.3V, for example. I've never tested regulators, but I could imagine protection components or other things that would end up shunting the current to ground as voltage approached a threshold.

And before he breaks out the 'this is within USB specs' argument again: At the time this hardware was designed, VBUS max was 5.25V. Any operaton above and beyond that is unspecified.

[SharpEars]

Also, I found it odd in discharging the phone that it stayed at 13% longer when charged at 5.3 V than at 5.0 V, so there maybe some mysterious activity here

Forget about those percentages if you want accurate results; you really need to measure the voltage and current into the cell together to determine the overall energy put in. Current will be harder to do since you'll need to insert a shunt inline, but voltage should be relatively easy.

Don't forget to account for the slight (but measurable) capacity loss every time you cycle the cell too...

But this is very difficult to do with devices like iPhones and iPads, because they are not trivial to take apart. There is also the role that any circuitry built into the cell may play.

[SharpEars]

There is a cheaper, easier, smaller, and more effective solution to the problem your scenario presents. It is called a battery.

www.amazon.com/dp/B005X1Y7I2

*wanders off*

You are going off the assumption that said battery based charger will not be dead as well, due to neglect. I would not make this assumption.

[SharpEars]

I'm glad it only took us 90 posts to realize that Apple probably knows how to design a USB power pack that will provide good charging performance.

Hey, if you want short concise answers, you've picked the wrong forum .

An iPhone 6 has an 1800 mAh battery. Assuming Apple programmed the charger to charge at 1C (to extend battery lifetime), the charger will use up to 1800 mA of current. It's a switching regulator, so it could use appreciably less current from the USB VBUS to achieve that. For example, 4V @ 1800mA = 5V @ 1.4A (assuming 100% efficiency).

I'm in the camp that thinks if you want to charge your phone faster, you'll have to swap the battery charger IC in your phone, and then pay dearly for it in 6 months when your battery is shot. That's when you'll really need your SupperFast charger (is it supper time yet? I'm hungry).

The increased current consumption you see at higher voltages is strange, but is probably due to operating near the upper limits of the battery charger. I've seen very strange behavior out of ICs before -- in deep-sleep mode, an ESP8266 will use hundreds of times more power if you're running it at 3.6V instead of 3.3V, for example. I've never tested regulators, but I could imagine protection components or other things that would end up shunting the current to ground as voltage approached a threshold.

The funny thing is that if they shunted the current to ground, it would go up more drastically. It, instead, appears to rise slightly and then dip slightly after 5.3 V or so, with increasing voltage and I've tested up to 6.1 V ! I don't see it drastically spiking up or down, so it would seem that if the excess power is not going to the battery, it is being converted to heat.

[Monkeh]

There is a cheaper, easier, smaller, and more effective solution to the problem your scenario presents. It is called a battery.

www.amazon.com/dp/B005X1Y7I2

*wanders off*

You are going off the assumption that said battery based charger will not be dead as well, due to neglect. I would not make this assumption.

Then let's not assume you're sharp enough to plug a charger into an outlet either..

You'd have to neglect one of those for many, many, many months before it self-discharges, and one would imagine you'd remember to charge it if you'd used it. Plus you can just leave it permanently connected to one of those Apple chargers you hate so much.

[amyk]

Also, I found it odd in discharging the phone that it stayed at 13% longer when charged at 5.3 V than at 5.0 V, so there maybe some mysterious activity here

Forget about those percentages if you want accurate results; you really need to measure the voltage and current into the cell together to determine the overall energy put in. Current will be harder to do since you'll need to insert a shunt inline, but voltage should be relatively easy.

Don't forget to account for the slight (but measurable) capacity loss every time you cycle the cell too...

But this is very difficult to do with devices like iPhones and iPads, because they are not trivial to take apart. There is also the role that any circuitry built into the cell may play.

It's not as easy as the others with user-removable batteries but the iPhone 5 mentioned above is pretty easy to get to the battery on. No glue to fight with, at least. The battery connector doesn't look so tiny either.

Circuitry on the cell will be limited to thermistor, protection, and a fuel gauge:

https://ripitapart.wordpress.com/tag/iphone-5-battery-pinout/

The iPad is going to be rather more difficult to get into... so some good measurements on the iPhone would probably be enough to put to rest all the speculation.

[rs20]

... so some good measurements on the iPhone would probably be enough to put to rest all the speculation.

Unless the iPad attempts to draw more current than the iPhone (definitely true), which the charging circuitry dropout + supply sag can't sustain (unknown).

Also, we haven't really accounted for where all this extra current is going, have we? Perhaps only of academic interest, but interesting to consider nevertheless.

[SharpEars]

Also, I found it odd in discharging the phone that it stayed at 13% longer when charged at 5.3 V than at 5.0 V, so there maybe some mysterious activity here

Forget about those percentages if you want accurate results; you really need to measure the voltage and current into the cell together to determine the overall energy put in. Current will be harder to do since you'll need to insert a shunt inline, but voltage should be relatively easy.

Don't forget to account for the slight (but measurable) capacity loss every time you cycle the cell too...

But this is very difficult to do with devices like iPhones and iPads, because they are not trivial to take apart. There is also the role that any circuitry built into the cell may play.

It's not as easy as the others with user-removable batteries but the iPhone 5 mentioned above is pretty easy to get to the battery on. No glue to fight with, at least. The battery connector doesn't look so tiny either.

Circuitry on the cell will be limited to thermistor, protection, and a fuel gauge:

https://ripitapart.wordpress.com/tag/iphone-5-battery-pinout/

The iPad is going to be rather more difficult to get into... so some good measurements on the iPhone would probably be enough to put to rest all the speculation.

Interesting, I will have to look into that...

[SharpEars]

... so some good measurements on the iPhone would probably be enough to put to rest all the speculation.

Unless the iPad attempts to draw more current than the iPhone (definitely true), which the charging circuitry dropout + supply sag can't sustain (unknown).

Also, we haven't really accounted for where all this extra current is going, have we? Perhaps only of academic interest, but interesting to consider nevertheless.

Well, assuming all of the charge amounts were equal as the charge gauge on my phone seemed to indicate, it's clear that the extra current is being converted into heat. The big question is by what? Maybe if I take the phone apart and start measuring around the circuit in/on the battery I can figure this out.

[suicidaleggroll]

Maybe the dc/dc converter is highly optimized for the expected voltage level of a stable 5.0v source and a 1m ~24 awg wire at the expected current draw?  So it's designed so the efficiency is optimal with an actual input voltage of ~4.75v, and when you try and feed it 5.3v the efficiency drops off?  I wouldn't expect it to drop off so quickly though.

[Niklas]

Charging 20 minutes from empty battery... Did you measure the actual current during the entire charge time of 20 minutes? An empty battery is typically charged with a lower current, maybe 10% of the fast charge current, until the cell voltage reaches a threshold to allow fast charging.

[SharpEars]

Charging 20 minutes from empty battery... Did you measure the actual current during the entire charge time of 20 minutes? An empty battery is typically charged with a lower current, maybe 10% of the fast charge current, until the cell voltage reaches a threshold to allow fast charging.

There was a slight increase in charging current start to finish, but nothing significant.