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Hi there,
some might know it some might not..
the Datakacabels can only charge the HTC Desire with 500mA (this will result in a Navigation System that DRAIN the Accu DOWN while charging...)
therefor you need the Special Vehicel Cable+Caradapter from HTC the cabel has some settings changed so it can actualy work as a AC adapter with 1000mA
can someone explain how to build your own AC cable with a Usal cable?
sorry for my bad english thou...
found the answer myself http://www.abload.de/image.php?img=usb_male_plug_type_a42xe.jpg connect both together or use Isolating tape on both
It should be the charger NOT the cable that has the data pins shorted. If you use a modified cable on a computer it will draw more than the 500 mA and you risk causing damage as this is out of specification for a USB port.
daverave999 said:
It should be the charger NOT the cable that has the data pins shorted. If you use a modified cable on a computer it will draw more than the 500 mA and you risk causing damage as this is out of specification for a USB port.
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Click to collapse
If USB tries to draw more than 500 mA then the USB standard has an overload protect so the PC should shut the USB port down (and present a notification via Windows) so you should not be able to overload but trust me, having to reset the USB port is a pain so best avoided anyway.
I'm curious as to how a device can draw more current than is being supplied to it? This isn't how it worked last I looked.
alias_neo said:
I'm curious as to how a device can draw more current than is being supplied to it? This isn't how it worked last I looked.
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Click to collapse
Good point. Perhaps the port is capable of supplying more? Maybe the power is supplied across multiple ports so if only one port is in use, more can be drawn?
But non the less, overload protection is there and functions.
I'm curious as to how a device can draw more current than is being supplied to it? This isn't how it worked last I looked.
Click to expand...
Click to collapse
Good point. Perhaps the port is capable of supplying more? Maybe the power is supplied across multiple ports so if only one port is in use, more can be drawn?
But non the less, overload protection is there and functions.
Click to expand...
Click to collapse
Most hubs or headers should be capable of supplying more. The 500mA limit is a specification of the standard and that is only in desktops and like. Less is possible as most of us have experienced. It wouldn't be too difficult to make a usb charger capable of 1A.
Iv searched high and low however for a ready made one from a third party. Unless its made by one of the big phone makers or similar you'll probably not find one and I settled for a 700mA one.
That said, charging slower is of course better for your battery.
EDIT: also, as mentioned, you would modify the charger not the cable. If the charger has no data pins it can't cause a problem. For PC charging you could make a fork cable.
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Alias::NeO on HTC Desire
I have older chargers for that output 5.0v / 550mA and have noticed that the Captivate outputs 5.0v / 700mA.
1. Can I safely use the older, 550mA chargers with the Captivate and what will the effect be?
2. Can I safely use the Captivate's 700mA charger with the older phones and what will the effect be?
Thanks.
1. Yes, you can use it. But it will charge slower.
2. Yes, you can use it. I believe that just because the charger output is higher amperage doesn't mean that it will affect the phone adversely. Think of it this way: A lamp is plugged into the wall outlet at your house. That outlet is rated at 120v 15A. The bulb isn't using all 15 amps, so no problem. But if you were to turn the voltage up or down, the lamp will get brighter or dimmer respectively.
The Captivate can take up to a 1A (1000 mA) charger.
Truceda said:
1. Yes, you can use it. But it will charge slower.
2. Yes, you can use it. I believe that just because the charger output is higher amperage doesn't mean that it will affect the phone adversely. Think of it this way: A lamp is plugged into the wall outlet at your house. That outlet is rated at 120v 15A. The bulb isn't using all 15 amps, so no problem. But if you were to turn the voltage up or down, the lamp will get brighter or dimmer respectively.
The Captivate can take up to a 1A (1000 mA) charger.
Click to expand...
Click to collapse
Another question. You sound smart on this so how about using the nexus one car charger on this? Fits perfect and I don't see why not, but still Leary. .. what do you think?
As long as it puts out 5v, (which is USB standard), you are fine. The amperage is only relevant if the device REQUIRES it. For instance if the device draws 1A and your charger could only handle 550mA your device will charge very slowly.
On the other hand if your charger can handle 1.2A and your device only draws 700mA, then your charger will only output 700mA.
The important thing is the voltage, it needs to be 5v +/- 3% ...
I actually use a generic car charger I bought at walmart with 2 USB ports on it, and it works well for every USB powered device I own ... ZUNE, iPOD, phones etc.
OK. Thanks for the reply. I had read that a phone requiring 700mA that uses a 550mA charger could damage the charger and possibly the phone. That's what made me wonder. And that's what led to the question.
Let's make this a bit more interesting. There's a local, highly-reputable cell phone repair store that has stopped selling car chargers because, they say, the rapid charge is not good for the phone's battery. Their recommendation is to use an inverter (no, they don't sell them) so that you can then plug a standard wall charger into it or a USB cable if the inverter is so equipped. The AC current that results from utilizing the inverter is more consistent than the current flowing from a car charger. So...I purchased an inverter for less than $20 and use it to charge the Captivate in my car.
OK ... not sure we need to get this far down in the weeds on this but here goes ....
The USB2 standard for power distribution is 5v and the thresholds are 4.4-5.25V.
Power is supplied in units of 5v power ... 1 unit is 5v at 100mA, no device can draw more than 5 units from any one port. If you have ever seen a portable hard drive with 2 USB connectors it is because it requires more than 500mA to operate and by using 2 ports the device can draw up to 1A. For dedicated chargers the 4.4-5.25v still applies but shorting the D+/- and disabling the data connection allows the device to detect that it is connected to a dedicated charging port and draw a maximum of 1.8A.
In keeping with the above guidelines, when connected to your computer the Captivate can draw no more than 1 unit of power which is [email protected], when connected to a dedicated charger the phone can draw [email protected] and stay within the standard. (yes, it caps itself at 1A, I know).
OK ... the next bit is going to be hard to digest because there are plenty of examples to the contrary ... there is a standard for mobile USB chargers, and it requires wiring them as dedicated charging ports. What this means to us is that, in theory anyway, a mobile USB charger should allow a device to draw up to 1.8A from it (highly unlikely ... but that's the standard as written).
Here is the problem, if the device is plugged into a dedicated charging port and tries to draw it's maximum rated current, that amount of current may not always be available or it may fluctuate. This fluctuation is what causes problems. Have you ever turned you car stereo up real loud and seen your headlights dim in beat with the music? Same thing, the power system is being drawn down. There are a couple of ways to stabalize your power system ... install a large capacitor (mine is 2 Farad) to provide "conditioning", or go the transformer route.A tansformer provides conditioning, but only on its own outputs... while a large cap will condition the entire power system if installed correctly.
So yes, using a quick charger on your phone can cause issues if your car has a ****ty power system or a large stereo system which is not set up properly (again, ****ty power system). Make sure your charging device is within the standard, and you should be fine wether it is USB via a cigarette lighter port or a 110V transformer.
I appreciate your detailed, helpful reply.
Other than the important 5v parameter, what I've taken away from your information is that a car charger can be used in a vehicle with a power supply that is known to be stable, and that either a whole-car conditioning system or an inverter should be used on one with a, shall we say, "less than stable" power supply (PG version ).
Jack45 said:
I appreciate your detailed, helpful reply.
Other than the important 5v parameter, what I've taken away from your information is that a car charger can be used in a vehicle with a power supply that is known to be stable, and that either a whole-car conditioning system or an inverter should be used on one with a, shall we say, "less than stable" power supply (PG version ).
Click to expand...
Click to collapse
Pretty much ...
There's more than one way to skin a cat, and that Transformer will cost you a whole lot less than a 2 Farad capacitor. I hate cats, but they serve a purpose.
@Battlehymn - one more question for you
I have converted from iPhone to the captivate (no haters please) - finally found a physical form factor with specs i like and the captivate rocks.
Anyway, I have some extra external batteries I used with my iphone that i want to use with my Captivate. I just bought a Female iPod connector and I am planning to connect it to a micro USB connector - the pinout is straight forward, but here is my question:
Should I connect the D+/- (short them together)? That is my plan. My batteries are 1900 or 1000 mAH - I assume that even if the phone tries to the draw 1.8A, the batteries have a circuit to only discharge so fast.
I am really frustrated with charging my phone.
From the wall, using the stock 700mA Samsung charger, I get 5% every 10 min.
From a USB cigarette lighter charger modified to source 750mA, I get 3% every 10 min.
From a USB cigarette lighter charger that can source 3A, I get hardly anything.
I assume from these findings that one or more of the following is true:
1. The phone knows when it is plugged into a stock charger.
2. The phone has a current limiter that prevents overcharging.
Does anyone have a charger, other than stock, that they recommend?
I'm half tempted to hook my stock charger up to a cigarette lighter inverter and power it that way.
(I'm also half-tempted to grab a current probe tomorrow and measure what the device is pulling.)
i havent really used my oem samsung wall charger much, but i know when i try to charge from my computers usb it takes 4EVER, thats why i jumped on this ebay deal
IBNobody said:
(I'm also half-tempted to grab a current probe tomorrow and measure what the device is pulling.)
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Click to collapse
I'd probe the chargers and see how accurate their ratings are as well....
does anyone know if using a 1mA charger would be okay? i have one left over from my evo.
The phone won't draw more than 500mA from a charger unless the USB data pins are connected.
Be careful, though... 99.9% of the chargers from China that claim to be 700mA (the nominal value of Samsung's) or 1A will overheat and die (or worse) if you try to actually draw that much current for any sustained length of time. I'd almost go so far as to say that it's SO EASY for a manufacturer to support high-power mode, I'd be automatically suspicious of any allegedly high power charger that doesn't ship with the pins shorted together.
Manufacturers know that most consumers don't know the difference (hell, most users HERE don't know the difference, and XDA is the upper crust elite of the Android phone universe), so they omit the shorting bridge and ship a charger with quoted power capacity that it MIGHT be able to sustain for a couple of minutes if you operated it in a walk-in freezer, knowing that most phones will never draw more than 500mA and it'll work fine for them. It lets them sell the charger for 99 cents AND pretend to be better than the others on the rack because it has a bigger "max power" value.
It's "RMS-vs-Peak" all over again.
Yeah I'm one of those that don't know much about the charging. I did figure there was a different charge rate when plugged into the wall and when plugged into usb or a usb converter like powerjolt.
I also found that one of the usb to micro's that I bought for using with my car powerjolt coverter won't let me connect via debugging/adb shell. was a little surprised at this... is it just a bad cord?
bitbang3r said:
The phone won't draw more than 500mA from a charger unless the USB data pins are connected.
Be careful, though... 99.9% of the chargers from China that claim to be 700mA (the nominal value of Samsung's) or 1A will overheat and die (or worse) if you try to actually draw that much current for any sustained length of time. I'd almost go so far as to say that it's SO EASY for a manufacturer to support high-power mode, I'd be automatically suspicious of any allegedly high power charger that doesn't ship with the pins shorted together.
Manufacturers know that most consumers don't know the difference (hell, most users HERE don't know the difference, and XDA is the upper crust elite of the Android phone universe), so they omit the shorting bridge and ship a charger with quoted power capacity that it MIGHT be able to sustain for a couple of minutes if you operated it in a walk-in freezer, knowing that most phones will never draw more than 500mA and it'll work fine for them. It lets them sell the charger for 99 cents AND pretend to be better than the others on the rack because it has a bigger "max power" value.
It's "RMS-vs-Peak" all over again.
Click to expand...
Click to collapse
D+ to D- must be shorted to get the high power mode? Maybe that was why my 3A supply was not handling it.
The Epic pulls 380mA when charging from a USB port from a Dell T3400 workstation. The result was steady at 40% and 80%.
I'll try out my other charging methods later and find out everything.
Stay tuned!
EDIT 1:
380mA is the magic number. It draws 380mA from all USB sources, including my two car chargers.
It draws 600mA from the wall adapter.
The wall adapter does indeed have D+ and D- shorted. My other chargers did not.
Here is the pinout for a USB port: http://pinouts.ru/Slots/USB_pinout.shtml
Here is the "beefy" USB charger I've been using:
http://www.wagan.com/index.php?page...ategory_id=22&option=com_virtuemart&Itemid=98
This charger is rather nice because the step-down supply (AX3002) has a large heatsink soldered to the ground tab.
It currently pulls up/down the D+/- lines via resistors. Each port is pulled down separately.
What I plan on doing next is to remove the pull resistors from one of the ports and short D+/- together.
Well, this explains a lot. This was really getting frustrating. I bought a "high-curent" charger for my car and the phone blows through the battery when I'm driving around with Maps running.
Im always on the road and for me an inverter in cigarette lighter with stock wall charger works best.the slowest charge is using stock usb cable since theres a slot for it on the inverter.2nd was radio shack car lighter in inverter.the inverter was from radio shack as well
Sent from my SPH-D700 using XDA App
IBNobody said:
Here is the pinout for a USB port: http://pinouts.ru/Slots/USB_pinout.shtml.
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Click to collapse
that is the official spec but there are actually not just four but six connectors on usb micro, which is how samsung can create a whole mess of pinut jumps for various amperage draws as well as data, entrainment dock and car dock.
OK so I need help clearing up some things about charging my phone. I have searched forums and google and I keep finding conflicting responses. I figured XDA may have plenty of knowledgeable people to clear things up. Here is what I think is correct. Please correct me if I'm wrong. I want to find a faster way to charge my phone.
USB data cables (with the exception of some that come from our phone manufacturers) are limited to 500mA because the data pins limit the current that goes through regardless of the rating of the wall adapter.
Example: you have a 1A AC adapter but your phone is only drawing 500mA when charging because you are using a data cable.
Charging cables have the data pins shorted (or missing) and will charge your phone at whatever mA the AC (or DC) adapter is rated at.
Your phone will also have a built in regulator to draw a certain amount of mA's regardless of what the adapter/cable are rated at.
Keeping all these things in mind, I have an AC adapter rated at 5V (standard for these phones) and 2.1A (2100 mA), and my factory samsung micro usb cable that is capable of data transfer as well. Since it is used for data transfer as well I wanted to buy a charging usb cable (with the data pins missing). My theory is this will remove all bottlenecks for charging speed and let the phone's battery pull what it needs, uninhibited by the usb cable and with more than enough current to keep a fast charging rate even when the phone is being used (light usage of course, I dont want to overheat the battery).
If anyone knows about this please clear things up for me, this would make it so much less inconvenient to give my phone a quick charge when needed.
This is my understanding, i might be incorrect:
The 500mA limit doesn't come from the cable but from the mainboard usb specifications.
USB2 can deliver upto 500mA, USB3 upto 900mA.
The different between the "charging" and "data" cables are most likely missing pines, but this has no influence on the current delivered via the cable.
I believe the phones uses the missing connections on a "charge" cable to detect it as charging from an outlet instead of a computer.
I would find it interesting to know if the phones charging routines differ depending on which power source, it thinks, it is connected to.
Probably some typos, but i'm tired ;-).
I guess only thing left to do is buy the usb cable without the data pins and see if it makes a difference. I'll post the results here.
Sent from my rooted GameBoy Color
As Dark3n stated, the limitation is with the USB port capabilities.
Ok you said you want to know the fastest way to charge. The fastest is with the phone off of couse. 2nd. Having a phone in airplane mode will charge fast.
Sent From Space Using My ICS Flavored Sensation
Ohh ok took a while to understand what he meant. Makes sense, thanks all this clears it up
Sent from my rooted GameBoy Color
The fastest method is to have a second battery and an external charger. A battery is much more portable than a charger if you are just out for a day, and if you are traveling, the extra battery & it's charger are not much more bulk than the phone charger alone. I go this route whenever possible as the benefits are inestimable.
With the advent of the S4, and its higher capacity battery, one could understand a higher charging current. However, I seem to have uncovered some findings that the charging system on the S4 is a bit more complex than first thought!
This is a bit techy, and assumes you have a basic amount of electrical knowledge, ie voltages, currents, resistance etc., but I'll try and keep it as simple as possible for anyone who may not!
To explain: The mains charger supplied with the S4 is a model number ETA-U90UWE, rated 5V @ 2A. However, the phone will ONLY charge at full current (which as I have measured so far, depending on what the phone regulates it to, typically sits in the region of 1.2 - 1.5A), when using the supplied charger (or possibly one of equal or higher current rating, depending on how it's configured internally), AND the supplied usb cable, OR any other usb cable, provided its shielding (the metal outer surface of the connectors) is connected at BOTH ends of the cable. Use a cable that doesn't have this shielding, and the charge current drops, regardless of whether there is plenty of current available or not. Use a different charger with an unshielded cable and the current drops even more, again regardless of whether it can supply plenty more current.
My assumption on this, is possibly an effort by Samsung to avoid the scenario of sticking 1.5 amps down a flimsy cheapo cable, the wires of which will likely be too thin to carry it.
After doing some probing around with a meter, I have managed to find a slight difference with the charger itself, compared to a generic one. In a generic one, the two data pins are usually just shorted together, which tells most phones that it's a mains charger rather than a USB port. On the Samsung one on the other hand, the pins appear to be shorted together, and also connected via resistors across the supply line (known as a potential divider), which holds these shorted data pins at a certain voltage. This is what tells the phone what sort of charger it's connected to.
Attached are a couple of diagrams to show the difference between the two chargers. There are in fact various setups of resistors that different manufacturers use to set the charging current, so it's quite easy to run into compatibility issues!
To make this a little less confusing I have done some preliminary experimenting, and I set out my results here.
For the test, I used combinations of 4 different usb style mains chargers: an apple iPhone one rated at 1A, an iPad one rated 2.4A, an HTC 1A one, and the genuine S4 one. With these I used two cables - the supplied Samsung S4 one (which is shielded), and a cheap generic one (which isn't). I started by measured the charging current directly with a meter, by using a very short usb breakout lead I've made, enabling me to interrupt the 5V line. However, I soon noticed that the use of any extension cables, even shielded, can lessen the chance of maintaining a good shielding connection, so I continued the exercise relying on the "galaxy charging current" app to get a reading.
Charger.................... Cable................ Current (A)
=====================================
HTC 1A.................Generic..................... 0.5
HTC 1A.................Samsung S4..............1.0
Apple 1A...............Generic......................0.5
Apple 1A...............Samsung S4..............1.0
Apple 2.4A............Generic......................0.6
Apple 2.4A............Samsung S4..............1.3
Samsung S4.........Generic...................... 0.8
Samsung S4.........Samsung S4...............1.3
So as you can see from these results, the original charger makes a difference, and the supplied cable (or a good quality shielded one) makes a further difference. If you have any further findings please feel free to add them here.
I can see that this is going to confuse some people, as it has me, as I'm sure some will inevitably try charging up their phone on generic chargers/leads at some point, with potentially long charging times resulting!
.
Very nice findings! Thanks for sharing them.
Not only what you say about longer charging time, but also discharging may occur (it has with me) while connected to the USB. I left my phone with USB tethering and it shut itself down after a couple of hours (it was low on battery already). I wanted to keep all the accessories in "new condition" in case I sell the phone in a few months, but I guess this justifies using the official charger and usb lead.
I hope someone can shed some light on the detection mechanism or the particular characteristics of the official cable so it can be replicated in generic ones.
From your findings, also Appe 2,4A charger has some control on the cable used, thanks.
Yes, but you won't be able to get more than about 0.75A out of it even with the samsung s4 cable.
You could try to add an extension cable to check if the charging system needs exclusively an original samsung cable from the charger to the phone.
Original samsung charger => extension cable male/female => original samsung cable => phone
PS: is there an app to check the charging current?
My experiments used an extension cable, that's the one I made into a breakout cable. So no it doesn't change by adding a cable.
There is an app, called galaxy charging current, which I tried also. In the 0.75A results above it showed a max permissible current of 1000mA, with the fully samsung setup it showed 1900mA. In the lower scenarios is showed up as 460mA. Other than that it doesn't tell you anything, it literally just shows you a max possible current, not the actual current it's drawing.
I've found out what the issue was, my generic cable was obviously a cheap one and wasn't shielded! I have edited my original post to re-explain.
Also I did a further test on a PC usb port - the Samsung cable allowed for 500mA, but the unshielded cheap one only allowed about 350mA, so (as pintycar found out), the phone actually carries on discharging in this case!
Interesting post.
I've been trying to mod a car charger so that the s4 draws more than 300mA so far unsucessful. I'm going to add in the 82K resistance and see what happens.
demusss said:
Interesting post.
I've been trying to mod a car charger so that the s4 draws more than 300mA so far unsucessful. I'm going to add in the 82K resistance and see what happens.
Click to expand...
Click to collapse
Hi,
Using a 5a digital bench power supply, I took a normal micro USB cable, cut it in two, added in the 82k resistors and tested.
Before: 450ma, after 1.73a
Then using a clamp meter I tested it with a 2amp Asus tablet charger - it varied between 1.48 and 1.61 amp.
I have since built a few more cables - one to use in my car (again 2 amp charger).
All in all, it works very effectively. Thanks for the initial research (saved me having to open my charger.)
BTW I suspect it is the charger where the resistors are, not the cable, otherwise the phone would try to pull 1.5a + from a laptop if you connected it.
Left my samsung cable at work so will test it tomorrow (if I remember)!
W.
Interesting. So basically for us laymen, you are telling us to use the original charger and cables to the extent possible ... right?
Can you clarify to me what an unshielded cable is? Maybe with a picture? I've got a blackberry's cable at work connected to my PC.
At home, I also have a cable and charger that I got with my Nexus S (I think this says Output 5.0V ~ 0.7A).
Would this be a problem or can I get by with these?
Thanks
I've been using the Samsung cable+charger+USB extension cable and charging the S4 usually takes about 4 hours, I'm going to try with just the Samsung cable next time and see if it makes any difference since people are saying that theirs can be fully charged within less than 3 hours.
Paparasee said:
Interesting. So basically for us laymen, you are telling us to use the original charger and cables to the extent possible ... right?
Can you clarify to me what an unshielded cable is? Maybe with a picture? I've got a blackberry's cable at work connected to my PC.
At home, I also have a cable and charger that I got with my Nexus S (I think this says Output 5.0V ~ 0.7A).
Would this be a problem or can I get by with these?
Thanks
Click to expand...
Click to collapse
Hi,
I believe (guess work here ) that only the original charger "needs" a shielded cable - could be checked by shorting the ground and shield on one side and see if it works at the higher current - if I am bored I may do it - it probably checks the shield and limits the current if it is not there (note I have not tested this so only going by the first posters findings).
BTW a shielded cable has a wire mesh around the 4 internal cables - this mesh avoids external interference messing with the signals. Can't see it affecting the charging though BUT shielded cables tend to have thicker internal cables so could be related to this.
I have it charging at 1.7a on an unshielded cable (thought he power strands are thicker than average) Shielding should only affect the data transfer speed, not the charging current.
If the Nexus S has only a 700mah charger then this will not be able to provide enough current for high speed charging and could easily burn out - nice smell, dead charger, not much else. therefore only use a normal unmodified usb cable (and it will charge at about 450mah).
W.
all this would eexplian why the charger that camewith my S2 dosen't appear to charge my phone fully over night...
For what it's worth I'm charging with a Note 1 charger...a thick shielded cable via the S3 docking station....and getting 900mah...
will get my original cable tonight and have a go tomorrow...
interesting read, my s4 lead and charger are still in the box and I'm using my nexus 10 ones phone charged from about 30% to full in just over 2. may have to change the old HTC £2 lead I've got connected to my works pc then, maybe why it's struggling to charge when playing music. guess this is one way to get people to buy more expensive cables
Very interesting read, thanks TS.
My original charger and cable set is still in the box; I've been using my Mom's old Galaxy Note charger.
I'll try the original cable + wall mount and see how fast it is compared to my current charger.
wmccann2 said:
Using a 5a digital bench power supply, I took a normal micro USB cable, cut it in two, added in the 82k resistors and tested.
Click to expand...
Click to collapse
Can you show me your final cable with a pic? Thanks
After this thread I have stopped using my blackberry bold cable to charge s4 and of course the cheap one too.. thanks op!
Sent from my GT-I9500 using xda app-developers app
I'm not sure if shielded vs. unshielded is the difference - probably wire gauge is the difference.
For example, if you shop at Monoprice, you have two options for USB cables: 28 gauge cables, and 24/28 gauge cables.
For wire gauge, lower is larger - the 24/28 gauge cables have thicker wires for the + and GND lines. A pure 28 gauge cable is likely to drop voltage a bit at high currents, and my observations have been that most newer devices, ESPECIALLY Qualcomm-based ones, are VERY finicky when it comes to input voltage drops.
As to the charger itself:
Apple chargers are almost guaranteed not to charge at full current, as they don't conform at all to the USB battery charging standard. Some newer Android devices do have at least partial detection of Apple chargers, so they may charge at 1A if an Apple charger is detected (any Apple charge, even 2.1A ones).
It sounds like the included official charger is a tablet-compatible one. Samsung tablets expect D+ and D- to be held by the charger at 1.2 or 1.8 volts (I forget which). As a result, Samsung tablets will not charge from standard chargers (like an N7 charger), but standard devices (like an N7) will charge from Samsung tablet chargers.
Now, the question is: Does the GS4 *require* a Samsung tablet-style charger, or did Samsung just include a tablet-style charger because it's backwards-compatible with standard devices? (less part numbers to track in inventory).
A useful pair of points would be: Using the same cable, does the Samsung charger behave significantly different from a Nexus 7 charger?
wmccann2 said:
Hi,
Using a 5a digital bench power supply, I took a normal micro USB cable, cut it in two, added in the 82k resistors and tested.
Before: 450ma, after 1.73a
Then using a clamp meter I tested it with a 2amp Asus tablet charger - it varied between 1.48 and 1.61 amp.
I have since built a few more cables - one to use in my car (again 2 amp charger).
All in all, it works very effectively. Thanks for the initial research (saved me having to open my charger.)
BTW I suspect it is the charger where the resistors are, not the cable, otherwise the phone would try to pull 1.5a + from a laptop if you connected it.
Left my samsung cable at work so will test it tomorrow (if I remember)!
W.
Click to expand...
Click to collapse
I missed this post on my first read-through: What happens if you just short D+ and D- when using the bench supply?