[Q] Disagreement between USB power measurements - General Questions and Answers

While charging via the OEM charger and cable, I measured power to my Samsung Exhibit II 4G T679 in three different ways:
- Kill A Watt P3 P4400 from Amazon, with the charger plugged into it
- "AboveTek" USB volt and power meter purchased from Amazon, plugged in just after the charger
- CurrentWidget app installed on the phone
Once it reaches steady state:
- Kill A Watt says 3.6W (if all this was preserved, then at 5V it would be 0.72A)
- USB meter says 0.55A at 5V (this is 2.75W)
- CurrentWidget says 1.1A (with the 3.7V battery this would be 4.07W
Needless to say, I am at a loss as to how these readings could be so different. I have tried it two ways -- with all three measurements going at once, and with only one at once. I always get the same results.
Which reading should I trust? Why do they appear so different?
For the record, I have also noticed similar phenomena with my Nexus 7. I could post those results in more detail if anyone would like.

Related

Fast charging N1

It seems the only way to fast charge a N1 is with the supplied wall charger. Standard Micro USB chargers whould only allow at much as 450mA of charge current regardless of the adapter current capacity.
The bundled charger however, manages to push 900mA into the N1. I made a cut in the charger wires and measured the current draw to make sure.
Now.. I'd like my car charger to be able to do the same. There must be some hack in the plug of the N1 charger since there are only 2 conductors from the case to the plug. You can see that the plug is somewhat longer than similar Micro USB plugs..
So I tried to see if one of the 3 unused pins can tell me anything but.. they seem unconnected as far as I could tell. Diode measurement (to test for any digital part inside) also did not produce any results. The next obvious step is to take the molded plug apart but I'd rather not...
Does anyone have any clue as to what makes that plug so special?
And please - I did my tests with a bench power supply - not the car chargers - so don't go around telling me it has to do with charger current capacity.
Thanks,
Nir
are you sure the micro usb cords you are using are able to handle the amps? most chargers made prior to now, only push about 450mA, the G1, and N1 chargers i have push a full amp though. I just ordered a car charger that pushes an amp too. There is nothing "special" about the plug.
followinginsanity said:
are you sure the micro usb cords you are using are able to handle the amps? most chargers made prior to now, only push about 450mA, the G1, and N1 chargers i have push a full amp though. I just ordered a car charger that pushes an amp too. There is nothing "special" about the plug.
Click to expand...
Click to collapse
I beg to differ. All the cords can easily supply 1 AMP. It is the phone itself that decides how much to draw from the charger based on something IN THE PLUG.
I am an electronics engineer so do understand I know perfectly what I am talking about
And your 1A car charger does not supply anything over 0.45A to the phone.. you will see that if you are using the phone while it charges (say nav or phone call) the phone actually looses some charge albeit it being charged... This will not happen with the stock wall charger.
I have a 900mAh car charger that I use and it does in fact give 900mAh to the phone while charging. I can tell because I used a 450mAh charger at home before and it was slooow and I could drain my phone while charging it. With the car charger I can stream music with spotify, use the GPS, have the screen on full brightness and the battery % will still go up.
I also bought a new wall charger recently, which is 850mAh on the USB port and has a 350mAh charger for a loose battery as well, works quite nice.
Has anyone measured the voltage or put a scope on the output of the stock charger?
maybe stock charger has a slight variance in voltage over USB chargers or some signalling going on and this tells the N1 to take more current from it?
I would like a solution to this too I've seen my phone discharge while on a supposedly 1A car charger using co-pilot.
SBS_ said:
I have a 900mAh car charger that I use and it does in fact give 900mAh to the phone while charging. I can tell because I used a 450mAh charger at home before and it was slooow and I could drain my phone while charging it. With the car charger I can stream music with spotify, use the GPS, have the screen on full brightness and the battery % will still go up.
I also bought a new wall charger recently, which is 850mAh on the USB port and has a 350mAh charger for a loose battery as well, works quite nice.
Click to expand...
Click to collapse
Forget the numbers on the chargers - what counts is what really goes into the phone and that needs to be measured with a current meter (test equipment). What you may think to be fast might not be that.
Original HTC chargers obviously do the trick of fast charging but this comes at a price compared to the $3-$4 garden variety on Ebay and the likes.
now I cannot help you with the electronics at all, but, my old HTC Touch Pro charger seems to charge the same as the one which came with the phone, is this correct?
(suits me if it is, as then I have a charger for home and work)
my blackberry bold 2 charger only says it outputs 700MAh, but both the google and htc chargers both say 1.0A
dnts said:
Forget the numbers on the chargers - what counts is what really goes into the phone and that needs to be measured with a current meter (test equipment). What you may think to be fast might not be that.
Original HTC chargers obviously do the trick of fast charging but this comes at a price compared to the $3-$4 garden variety on Ebay and the likes.
Click to expand...
Click to collapse
Yes, it is just anecdotal evidence as I don't have any equipment to measure it. But my phone no longer discharges when I use it while charging, which it used to do with the old charger I used. So while I can say for a fact that the charger I use now is faster, I can't say by how much (this goes for both the car charger and the one I put in the wall socket).
I ordered this charger a few weeks ago and it charges my phone as fast as the original charger. The label says 5v / 1200mA.
Genuine Nokia Mini AC-10U US Type AC Charger (100~240V)
$7,25 and free shipping. (Takes a while before you get it tho.)
GazzaK said:
now I cannot help you with the electronics at all, but, my old HTC Touch Pro charger seems to charge the same as the one which came with the phone, is this correct?
Click to expand...
Click to collapse
HTC Touch Pro = mini USB
Nexus One = micro USB
Not an engineering here, but I am guessing the phone not always drawing more than 500ma may be is to do with the charger itself.
There is this "fast charge" USB standard where a wall plug has the USB data pins shorted to indicate that it is a wall plug and hence the phone knows when to draw more power. So even if the charger is rated 1A, the phone might not know if it could utilize that if those pins aren't shorted. Try doing a quick Google on this ....
If someone can test if the stock charger that came with the phone in fact does have those pins shorted that would confirm part of this theory.
For all practical purpose - I used two cables/plugs with a bench adjustable power supply. Simple micro USB plug would only let me draw 450mA regardless of power supply voltage in the range 4.5-5.5V. Tried shorting data pins - nothing. Tried shorting spare pin to VCC or GND or any of the other pins - nothing.
Used original cable and plug - draws 900mA at voltages from 4.9-5.5.
So it's in the plug somehow.
Tried (very difficult) to see if the pins on the plug are shorted and all 3 spares (except for 5V and GND) seems unconnected.
Next step is the irreversible hot knife...
I'm bugged by this, too. I tested with my desktop dock connected to my car charger (which states 1000 mA): it loads slowly and my battery widget reports USB- instead of AC-charger.
Might it be that the phone tries to load more than 1000 mA at the beginning to be sure that it doesn't overload the charger? And if that fails, it falls back to 500 mA?
Could N1 use a simple logic of:
- always watch the voltage
- start drawing 500ma (or whichever is the lowest current as per USB spec)
- increment in say 50ma steps
- if voltage drops below 4.x V, back off and stay at that level
I just did a little test of my own. I have a Palm Pre car charger (actual Palm brand one labeled as 1000ma output) and I plunged my N1 into it on my way home from work. In twenty eight minutes, my battery went from 47% to 70%. Much faster than plugging into my computer, which is 500ma max. I don't have any fancy test equipment, and don't claim to know a whole lot about electronics, but seems pretty fast to me.
I have a 4-port 2A 5v USB charger, and connecting it to my Nexus OR Milestone with a MicroUSB cable (the one that shipped with either phone, or the one from my Kindle) yields painfully slow charging - it basically won't charge if you are using the phone.
Connecting the Nexus One charger yields fast charging on either phone - so it is not HTC (or Motorola) proprietary.
The Milestone comes with a 900mA USB plug, and connecting THAT to either phone with either of the MicroUSB cables yields fast charging.
I have another aftermarket 2 port 2A 5V USB wall charger (brand: T'nB) AND I have an iPhone USB plug, and both give fast charging on the Milestone, and I have not yet tried them on the Nexus One.
Breakdown (on things I've tried):
FAST CHARGING on Nexus One AND Milestone:
Nexus charger (either in the US (110v/60hz) or in France (220v/50hz) through an adaptor)
Milestone wall French USB plug (which I think is something odd like 850mA at 5.9v) with ANY microUSB cable (in fact, it seems to charge both of the phones faster than the stock Nexus One plug)
SLOW CHARGING on Nexus One AND Milestone:
USB plug on computer
One aftermarket 4 port 2A 5V USB charger (NOT a hub, only a charger)
FAST CHARGING on Milestone, untested with Nexus One
T'nB 2 port 5v 2A USB wall charger
Apple iPhone 1 port 1A 5v USB wall adaptor
Seems found the answer for Fast Charging N1
I had just do some test for Charging N1 With Original AC Charger , Other band USB Charger and PC USB charger.
1. Orginal Charger give N1 from 0% to 100% at about 2 hour and something.
2. The other band AC charger and PC USB Charger can only finish the same job over 5 to 6 hours.
The Fast Charging is Due to 5.1V (Measured at N1) and 5.2V(Measured inside AC charger). 0.1V Drop is due to resistance of USB cable.
The Slow charged is due to 4.8V (measured at N1) and 5.0V (measured on PC USB and Other AC Charger)
i.e. Original Charger mod from 5.0 V to 5.2V (about 10% increase in Voltage)
Looks my theory is correct then ? N1 watches the voltage and if it droops too much, it backs off the current.
So the key would be: get a charger than can maintain at least 1A @ 5.2V, use
a decent gauge, short wire from the brick to N1.
Has anyone tried a Blackberry charger on the N1? Will they work to full capacity as well? (They're on Amazon for a fiver)
Because the nokia charger is working
http://pinoutsguide.com/CellularPhones-Nokia/micro_usb_connector_pinout.shtml
see info under table.
I tested also HP charger + standard USB cable delivered with Nexus, and it is charching cca 1A.
Then I tested one noname Carcharger + standard USB cable delivered with Nexus, and also charging cca 1A.
I dismantle the noname carcharger and here is a result:
data line (pin2+3) is shorted and connected do + (pin1 ,Vcc) thrue resistor cca 630kOhm.
1 - 4 = 5.1V
2,3 - 4 = 3.2V
rashid11 said:
Looks my theory is correct then ? N1 watches the voltage and if it droops too much, it backs off the current.
So the key would be: get a charger than can maintain at least 1A @ 5.2V, use
a decent gauge, short wire from the brick to N1.
Click to expand...
Click to collapse
I try to use power supply 5.2V 2A with cable without dataline (pin 2and3 not connected) and it is charging 480mA only.
I have now tested with an HTC car charger for the HD2. It's fast charging (tested with Waze running, two bluetooth connections and playing mp3 - and it's still loading the battery, whereas before it would be stuck at the current percentage) and even shows AC power instead of USB.

Recharge the Infuse Battery a little faster.

I started using "Battery Monitor Widget" free by 3c
a few days age.
I noticed that the charging current using the Samsung plug in charger was about 300 ma higher than the charging current using other USB chargers. I read on other battery threads that Data + and - are connected on the Samsung charger to prevent the USB screen from appearing. I wanted to know weather the connection of D+ and D- had any thing to do with this so I opened up one of my other USB chargers and soldered the two middle pins (d+and d-) together. After making this change, I got an additional 300ma out of this charger.
According to Battery Monitor Widget, when charging the battery from 50%, the Samsung charger was putting out around 1180ma. Unmodified USB chargers put out about 820ma. The max current output listed on the charger makes no difference in the result.
The charging time from 50% to 100% was reduced by 25% using chargers with d+ and d- connected.
This is actually very interesting. I have been trying to figure out how to make the phones charge faster and have been searching for higher ma chargers. I wonder if there is a way to modify the cable to achve he same results.
I've noticed that sometimes plugging my phone into one charger triggers usb mode but other chargers do not.
Sent from my SCH-I510 using XDA App
terryneely said:
I started using "Battery Monitor Widget" free by 3c
a few days age.
I noticed that the charging current using the Samsung plug in charger was about 300 ma higher than the charging current using other USB chargers. I read on other battery threads that Data + and - are connected on the Samsung charger to prevent the USB screen from appearing. I wanted to know weather the connection of D+ and D- had any thing to do with this so I opened up one of my other USB chargers and soldered the two middle pins (d+and d-) together. After making this change, I got an additional 300ma out of this charger.
According to Battery Monitor Widget, when charging the battery from 50%, the Samsung charger was putting out around 1180ma. Unmodified USB chargers put out about 820ma. The max current output listed on the charger makes no difference in the result.
The charging time from 50% to 100% was reduced by 25% using chargers with d+ and d- connected.
Click to expand...
Click to collapse
Post this up in Entropy512's thread here
http://forum.xda-developers.com/showthread.php?t=1220386
he's doing battery charging research. This might be helpful to him
Nope not useful at all - nothing new.
1) It's not 300 mA more. CurrentWidget has a 1.83x scale factor. Covered in the thread above. It's 125 mA more.
2) I'm fully aware that shorting D+ and D- together puts you in AC charging mode, in compliance with revision 1.2 of the USB Battery Charging specification. I'm also fully aware that iPad/iPod/iPhone chargers get treated by our phone as a regular USB port and not as an AC charger.
USB charging is 475 mA. AC charging is 600 mA, unless you're running one of my kernels with charginghacks - in which case it can hit 800 mA when the battery is below 4.0 volts.
Right now, I don't need any more data from the Infuse. I need someone with a Captivate or i9000 to run CurrentWidget tests, I'm looking for VERY specific things.
Uncle Irish said:
Post this up in Entropy512's thread here
http://forum.xda-developers.com/showthread.php?t=1220386
he's doing battery charging research. This might be helpful to him
Click to expand...
Click to collapse
The Forum will not let me post on this thread, perhaps someone could post it there for me.
terryneely said:
The Forum will not let me post on this thread, perhaps someone could post it there for me.
Click to expand...
Click to collapse
Please don't post in that thread unless you own a Captivate or i9000 and are able to collect the data I'm asking for. It's not a generic battery research thread - I understand a great deal about how our device works and don't need any more data from Infuse owners at this time. What I DO need is more details and testing with the Captivate since I see many people claim they charge significantly faster despite the charge current limit being the same.
Also, if you had read the linked thread you'd see (as I mention in my post above) - this isn't a new discovery.
Settle Down, The AC charger mode is not covered in the Infuse General thread. It is worth mention here to got the word out. No one is trying to take over YOUR battery thread.
Progress?
Entropy512 said:
Nope not useful at all - nothing new.
1) It's not 300 mA more. CurrentWidget has a 1.83x scale factor. Covered in the thread above. It's 125 mA more.
2) I'm fully aware that shorting D+ and D- together puts you in AC charging mode, in compliance with revision 1.2 of the USB Battery Charging specification. I'm also fully aware that iPad/iPod/iPhone chargers get treated by our phone as a regular USB port and not as an AC charger.
USB charging is 475 mA. AC charging is 600 mA, unless you're running one of my kernels with charginghacks - in which case it can hit 800 mA when the battery is below 4.0 volts.
Right now, I don't need any more data from the Infuse. I need someone with a Captivate or i9000 to run CurrentWidget tests, I'm looking for VERY specific things.
Click to expand...
Click to collapse
Hi entropy,
Im a noob to the forum, but have read your other thread that requests info from captivate users. Sorry not a captivate user here as I am a infuse 4g user with the same freaking complaints from everyone else.. slow charge up time, fast discharge.
Just want to know the update of your investigation and if any progress has been made with improving the battery charge/discharge. I ve been able to improve the discharge rate with JuiceDefender and watch the progress with JuicePlotter from the market. But that only controls the discharge and not the important aspects of the battery as you seek.
Also, minor point I noticed, is when there is a difference when charging the phone in plane mode versus Juicedefender running (and w/out it). Would you like some numbers? I realize this might not be new for you considering the info you posted about charge being split depending what the phone is doing. So, it makes sense if its in plane mode it will charge up faster.

Findings on Galaxy S4 charging current

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.
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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?

Charging Speeds

Hi,
Wanted your thoughts and opinions on charging speeds. I've never actually timed how long it takes to charge. i leave it overnight and it's ready when i wake up.
When i plug the phone into the charger, it flashes up slow charging for 2 seconds then disappears. which got me wondering how much it's actually using.
i used to use Current Widget app on my Samsung S3 which told me exactly how much current the phone was taking from the charger. typically it was 1A via AC/mains and 499mA from a PC. Plugged in to AC, I could play a power hungry game and it would still charge the phone at a good rate.
The LG kernel doesn't like these apps - the mA value is all over the place but it's typically <500mA displayed.
I could buy a USB ammeter to work out how much the USB charger is supplying but do you have any other methods of finding out? Do you know what your phone uses?
at home, i use a Xtrememac dual USB charger, 2x 2.1A output with a shielded 3M USB cable. for those wondering, it's the same regardless what cable i use. Have also tried with generic usb chargers, iPad chargers and official and OEM cables from LG and various other manufacturers. Have also used a data-shorted USB cable from PC which is the same result.
I haven't tried the LG charger yet (mainly as it's a 2 flat-pin plug and i don't know where i put the box) but i think i recall it being a 1.8A charger.
I use an application called "charger report" which can display current consumption and Xtar "USB detector" device. They both show the same numbers. But Xtar USB detector can detect voltage of a charger. The charging current of LG g pro 2 is 1.4-1.5A when the smartphone is not used and higher when I use it. Using USB detector I found out that this smartphone can charge with maximum current a charger can give only if the charger's voltage is 5.3v. So it chargers at full speed with original charger and two other chargers I have: a charger from my Lenovo s6000 (2A 5.4V) and from my Asus t100 (2A 5.3V).
i tried that app too and got the same results as with Current Widget.
i'll buy a "usb detector". thanks.
I forgot to mention that it take approximately two hours for charging indicator to reach 100% when the smartphone reports that it fully charged. And it's necessary to left it connected to a charger for ten to twenty minutes to be really fully charged. Otherwise charging indicator will soon drop to 90%. One can tell if a smartphone is still charging by touching a charger or by looking at current consumption: a charger would be warm and current would be higher than 200mA.
Is the GP2 Quick Charge (1 or 2) enabled? I can't read anything about it other than it's in Snapdragon chipsets. Not sure if it can be disabled or not.
ray-lee said:
Is the GP2 Quick Charge (1 or 2) enabled? I can't read anything about it other than it's in Snapdragon chipsets. Not sure if it can be disabled or not.
Click to expand...
Click to collapse
The Snapdragon 800,801 and 805 is for Quick Charge 2.0
The Snapdragon 600 for 1.0
ok, does anyone use a Quick Charger with their GP2? is it noticeably faster?
not yet available in Austria, I have read it kills the battery life on
ray-lee said:
Hi,
Wanted your thoughts and opinions on charging speeds. I've never actually timed how long it takes to charge. i leave it overnight and it's ready when i wake up.
When i plug the phone into the charger, it flashes up slow charging for 2 seconds then disappears. which got me wondering how much it's actually using.
i used to use Current Widget app on my Samsung S3 which told me exactly how much current the phone was taking from the charger. typically it was 1A via AC/mains and 499mA from a PC. Plugged in to AC, I could play a power hungry game and it would still charge the phone at a good rate.
The LG kernel doesn't like these apps - the mA value is all over the place but it's typically <500mA displayed.
I could buy a USB ammeter to work out how much the USB charger is supplying but do you have any other methods of finding out? Do you know what your phone uses?
at home, i use a Xtrememac dual USB charger, 2x 2.1A output with a shielded 3M USB cable. for those wondering, it's the same regardless what cable i use. Have also tried with generic usb chargers, iPad chargers and official and OEM cables from LG and various other manufacturers. Have also used a data-shorted USB cable from PC which is the same result.
I haven't tried the LG charger yet (mainly as it's a 2 flat-pin plug and i don't know where i put the box) but i think i recall it being a 1.8A charger.
Click to expand...
Click to collapse
Hey ray-lee!
I just bought this phone and as it seems it could get someday similar problems as my former phone the Galaxy Note 2.
That phone has had problems with charger and cable also. I had to buy another set of charger and cable since the original ones gave up a few months after i purchased the phone (it was used). The cable managed only 500mA wich is very slow for a battery that strong. One night was once not enough to charge my phone from 30% to 100%. As it seems it is problematic to manufacture cables, that can hold up and continually grant the 1,8 A that would charge our device in just 2 hours. I read somewhere that the G Pro 2 is one of 5 devices that has blazing fast speeds on charging the battery. If you handle the cables with caution hopefully you will not encounter problems. If so my guess is, that you will have a hard time in finding a cable that can hold up. Sadly the stock cables are always more expensive. I do not get it, why companies dont build travel adapters that only charge ur phones built solid with sturdy cables to ensure the transmission of high currents. That way with charger + usb cable is just stupid, even when tis is an all in one solution.
I like this phone very much and i hope, that the cables will not be that sloppy as the cables that Samsung had/ still has. With Current Widget i get readings around 1500 mA (1,5 A) when connected to the stock charger. And yes the LG Charger is an 1,8 A one. I have also flat pins, but received an adapter to be able to connect it in Hugary.
Just sharing thoughts here, that will maybe helpful to someone...
:highfive:
2amp charger, charges my Pro 2 in apprx 1 hour while my old LG 1amp charger fills it in 1.40 hours apprx
ray-lee said:
Is the GP2 Quick Charge (1 or 2) enabled? I can't read anything about it other than it's in Snapdragon chipsets. Not sure if it can be disabled or not.
Click to expand...
Click to collapse
i "think" as long as device has snapdragon it is Quick Charge enabled
I use the "Charging Report" app on my phone, and it reports proper values.
(Around 1500mAh with the LG charger, and around 1600mAh with the 2.0A Samsung charger.)
If your phone is charging slowly, check the CABLE. Cable can broke too.
(Many people complain about their Samsung charging cables, because they just stop delivering power after a while and just charge the device slowly.)
Anyone tried Quick charge 2.0?? https://www.qualcomm.com/products/snapdragon/quick-charge
enkhtwshn said:
Anyone tried Quick charge 2.0?? https://www.qualcomm.com/products/snapdragon/quick-charge
Click to expand...
Click to collapse
All Devices with the Snapdragon 800 have Quick Charge 2.0!
letschky said:
All Devices with the Snapdragon 800 have Quick Charge 2.0!
Click to expand...
Click to collapse
So anyone tried it? That is the question
Yes, I have the Motorola Turbo Charger.
coastalmikey said:
Yes, I have the Motorola Turbo Charger.
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Click to collapse
How long does it charge from 0-50 from50-100 from 0-100?
There aren't many chargers out there. and the ones that are, are usually US 2 pin. I need a UK 3 pin or travel charger (changeable pins) really.
enkhtwshn said:
So anyone tried it? That is the question
Click to expand...
Click to collapse
To achieve full charging speeds, a Quick Charge 2.0 enabled device must be paired with a Quick Charge 2.0 certified adapter

[Q] Charging w/ alternate chargers... a risk?

I bought a brand-new Nexus 5 a few weeks ago. However it came with a 0.85A wall charger which is LG branded... and some 'generic' cable that was included too. Used it twice, but it took around 8-10 hours just to charge 80% of it. I plugged my old Galaxy Ace USB cable to the LG charger and it reduced to two and a half hours, same with my alternate charger from the aforementioned phone (5.0V + 0.7A).
But this led me to a question: Is using alternate chargers with < 1.2A of output a risky way to charge my Nexus 5 battery? I saw somewhere that it might even damage the circuit board (a rare case) and I'm a bit worried about it.
Using a charger with a lower amperage output will take longer for the phone to charge. Also, using a cheaper cable will also lengthen the charge time as the cable can pass the full amount of power to the phone. This has been my experience with using oem cables vs dolls store cables me chargers.
audit13 said:
Using a charger with a lower amperage output will take longer for the phone to charge. Also, using a cheaper cable will also lengthen the charge time as the cable can pass the full amount of power to the phone. This has been my experience with using oem cables vs dolls store cables me chargers.
Click to expand...
Click to collapse
But... Will a Samsung wall charger with 0.7A of output damage my phone if I use it as my main charger? Because I also have a chinaphone which came with a bad charger and the Samsung one works fine.
No, the Samsung charger @ 0.7A will not damage the phone. I use a 1.0 A and 2.0 A Samsung charger with my N5 and it has been fine for months and months.
With the Samsung 0.7A charger, battery gets charged in 2:10 hours. I still don't understand it since I came from a low-end Samsung device which could complete its charge in about three hours (and that one had a 1500mAh battery...)
This is a tricky question, no doubt about it.
IMO, the cable quality is way more important than the current output (0.7 A, 0.85 A, etc).
I have a Samsung S4 charger with its cable (it seems very well built and it's thicker than other cables) and my N5 goes from 10% to fully charged in less than 3 hours.
Funny facts - happened to me:
- I had a very cheap cable (probably from China) that came with a battery bank. Surprisingly, it was the fastest way to charge my phone - reached almost 2.0 A. Later I found the trick: this cable doesn't have all the four wires, it only had two (positive and negative, without the data wires). I believe the data wires is used to perform some kind of amperage control; without it, no control was done and led to a very fast (probably dangerous) charging. I don't use this cable anymore, chances are that this nasty cable screwed up my notebook battery
- My N5 is almost two years old. Recently I had a problem with the Power button, the internal contact of the switch on the board was stuck 'pressed' and this led my phone to an endlessly force-reboot. I discovered this behavior after some google search and one of the possible causes of it is exactly the usage of a non-default / faster charger, it said that this could melt something - SOURCE
It makes sense, but I can't confirm this. I was able to fix this by smashing the phone on a table a few times (lol) and I'm still using a non-default charger
Can anyone confirm / say something about these facts?
For those who wants to see the diference between cables and chargers, give this app a try:
Play Store - Ampere
This app is a current meter, I use it on a regular basis and it is pretty reliable - the dev it's a XDA member and this app can be discussed here
Hope this helps!
You can not harm a phone with a 5 volt charger. The phone takes the amps it needs. More is better than less. I use 2 amp, 5 volt ones. As has been said the usb cable is the key thing. The better quality the better charge.

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