Meh. Much ado about nothing. Sorry.
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)
Quote2. 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 (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 (https://www.eevblog.com/forum/buysellwanted/franky's-sales-thread/msg694265/#msg694265)
I purchased a couple of them and they are very accurate.
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?
But, I agree with others. I've had no issues with Apple charges over many years.
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 :-DD
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 :-DD
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.
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'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.
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.
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..
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.
What Iphone device do you have. Some can only charge at 1A no matter the wire or charger.
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...
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.
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.
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.
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! :box:
Incidentally,I suggest editing the topic title to "Sick of Apple?". If you don't like the behaviour/performance, don't buy the kit! 8)
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! :-DD
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.
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.
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...
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.
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 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).
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.
This was from a previous design, without the meters.
I must say it is much better with the meters.
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?
Oh, I see... You separated the tan power supply board from the computer and added the daughter card.
The 2.7 were just obtained with voltage dividers with 2 resistors.
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.
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.
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 (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.
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 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?
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.
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 (http://compliance.usb.org/index.asp?UpdateFile=Electrical#98), likely because most if not all existing devices were fine with 5.5V anyway and this gives a wider 10% tolerance.
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?
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.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.
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?
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 (http://compliance.usb.org/index.asp?UpdateFile=Electrical#98), likely because most if not all existing devices were fine with 5.5V anyway and this gives a wider 10% tolerance.
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.
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.
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.
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
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...
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.
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:
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?)
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.
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 (http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html)
with a lot of additional information on this topic.
(https://www.eevblog.com/forum/projects/sick-of-apple-chargers-suppercharger-the-next-generation/?action=dlattach;attach=161520)
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 outputvoltage (andcurrent)." 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).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.
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 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.
| 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 |
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 hereForget 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.
...and you won't be packing a battery charger
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.
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.
QuoteAlso, 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 hereForget 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...
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 (http://www.amazon.com/dp/B005X1Y7I2)
*wanders off*
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 :box: .
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).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.
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.
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 (http://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.
It's not as easy as the others with user-removable batteries but the iPhone 5 mentioned above is pretty easy (https://www.ifixit.com/Teardown/iPhone+5+Teardown/10525) to get to the battery on. No glue to fight with, at least. The battery connector doesn't look so tiny either.QuoteAlso, 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 hereForget 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.
... 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).
It's not as easy as the others with user-removable batteries but the iPhone 5 mentioned above is pretty easy (https://www.ifixit.com/Teardown/iPhone+5+Teardown/10525) to get to the battery on. No glue to fight with, at least. The battery connector doesn't look so tiny either.QuoteAlso, 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 hereForget 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.
Circuitry on the cell will be limited to thermistor, protection, and a fuel gauge:
https://ripitapart.wordpress.com/tag/iphone-5-battery-pinout/ (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.
... 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.
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.