Charger / USB cable variability and problems - Galaxy S III Q&A, Help & Troubleshooting

The forums are all filled with comments from (more or less experienced) people complaining that recharging their S3 might be at times strange with a certain ROM or another - and while maybe 10% of the time that might be indeed the case, in 90% of the cases it boils down to problems with CHARGERS and USB CABLES.
Right now it seems that the amount of power used for recharging is controlled primarily by S3 itself using at least 3 levels - of which at least two can be fine-tuned in software (and some kernels expose those features).
There is an "AC charger level" (set around 1000 mA), an "USB level" (set around 500 mA since USB1/2 standard does specify that) and a 3rd "low level / safety level" which seems to be around 50-100 mA.
The S3 seems to be choosing the level based on BOTH the charger and the USB cable used - and I have seen the same charger showing a different level with different USB cables, and the same USB cable showing a different level with different chargers. I have even seen one AC charger that with a very specific cable (not the one bundled with it) was showing "charging/USB" inside the S3, while all other cables on the same charger were showing "charging A/C".
So when your S3 charges very-very slowly your very first check should be with another USB cable, and second check should be from a different charger or USB port - instead of posting same questions again and again around here
IMHO the absolute safest charging combination right now is with the original Samsung USB cable from the USB port (ideally in a good notebook - good notebooks have very effective USB protection, and some - like the Thinkpad models - have an USB port that can power something even when the notebook is stopped, and with one extra BIOS setting even when the notebook is stopped and not connected to A/C)! This is not the fastest charging combination - and with an extended battery it might take like 9 hours for a full-full charge (4 hours with normal battery) - but is most likely the safest (simple) one! Also by charging with a smaller current the heat generated is (much) smaller and the "aging" of the battery is drastically reduced.
If you are in a huge-huge hurry you might want to use the original Samsung A/C charger plus the original Samsung USB cable, but don't "overdo it" by trying forced/exotic solutions/chargers - we even have an entire thread around here at XDA with "sudden death" cases - most of them observed in the morning after the i9300 was left overnight in some A/C charger
EDIT:
Also if you see a very-very slow charge (or even a discharge) while you are "charging" but you have the screen ON and the CPUs running at full speed you should know that is possibly normal - since screen ON + CPU at 100% is draining more than 500 mA (= probably most of, or more than you are getting from the cable); try to lock the phone or even power it off, and then after 20 minutes see if the battery is better and by how much.
EDIT2:
As a far later step if everything else fails you should also check if the pins inside the USB connector in the S3 are not bent in any way, but that is slightly more advanced and might not be perfectly fixed without replacing the connector.
Also if your phone has other serious hardware problems (cracked screen or so) you should mention that first.
EDIT3:
My stuff above was "educated guess" - now we also have 'hard technical data":
http://www.maximintegrated.com/app-notes/index.mvp/id/4803#5

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Nice topic thanks for comprehensive content. I have been experiencing slow charges since i get my S3. I read about a guy, whos charging cable is officially changed by Sammy with a 5-pinned one, and fortunalately found a same type of cable. Since i started using that cable full charges take approximately 2 hours while using the original one results in 4 hours or so.. I also informed my local samsung service about the issue but they refused my explanations saying that there is no such an official report about the faulty original cables.
I was frustrated about dischages while playing games when the phone is plugged in. IMO this is one of the biggest fail for a phone to be discharged while plugged in.. But now it is completely fixed.
Sent from my GT-I9300 using xda premium

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ggnoplay said:
Nice topic thanks for comprehensive content. I have been experiencing slow charges since i get my S3. I read about a guy, whos charging cable is officially changed by Sammy with a 5-pinned one, and fortunalately found a same type of cable. Since i started using that cable full charges take approximately 2 hours while using the original one results in 4 hours or so.. I also informed my local samsung service about the issue but they refused my explanations saying that there is no such an official report about the faulty original cables.
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Click to expand...
Click to collapse
The math is just right - 2000 mAh battery = 500 mA * 4 hours = 1000 mA * 2 hours.

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My original usb + charger takes 5 to 8 hours and it has 5 pins !!!!
also I tried another 5 pins usb with the same original charger and it takes around 2:30 to 3:30 hours
So I need to buy a 5 pin usb one but how to guarantee it will work ????

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xclub_101 said:
IMHO the absolute safest charging combination right now is with the original Samsung USB cable from the USB port (ideally in a good notebook - good notebooks have very effective USB protection, and some - like the Thinkpad models - have an USB port that can power something even when the notebook is stopped, and with one extra BIOS setting even when the notebook is stopped and not connected to A/C)! This is not the fastest charging combination - and with an extended battery it might take like 9 hours for a full-full charge (4 hours with normal battery) - but is most likely the safest (simple) one! Also by charging with a smaller current the heat generated is (much) smaller and the "aging" of the battery is drastically reduced.
Click to expand...
Click to collapse
I agree with this... in one night i used to recharge my S3 with a Blackberry Charger. Guess what? The digitizer went up like crazy, started to write crazy stuff (just 'zeroes' 00000). i immediately dissconected the charged and the digitizer when back to normal.

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zeromant said:
I agree with this... in one night i used to recharge my S3 with a Blackberry Charger. Guess what? The digitizer went up like crazy, started to write crazy stuff (just 'zeroes' 00000). i immediately dissconected the charged and the digitizer when back to normal.
Click to expand...
Click to collapse
Yes, I have also seen something similar once with a very bad low-cost Chinese charger.
I also wanted to add some "hard" info to this thread - my stuff above was "educated guess" but in the meantime the full info become available and I added a link below with it (coming recently from the Perseus kernel thread) - as it can be seen from there there are basically 3 modes (but with the first one by default starting in 100mA, so this one should be either 100 if something goes wrong or go to 500mA).
http://www.maximintegrated.com/app-notes/index.mvp/id/4803#5

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This is a very informative post. Recently I have been experiencing weird battery behavior on my s3 as well and wanted to investigate further.
I have 2 original Samsung batteries and using an original Samsung OEM charger to charge my S3 and Grand i9082. (both uses same 2100mah battery)
Now both the batteries and the charger charges and holds the current fast and long in case of grand i9082. (gives me more than 24 hrs on average usage and almost a day with wifi, cellular data on for dual sim, along with moderate messaging and youtube) no Issues at all on both these batteries and charger.
On my s3 it's a different story.
In 2-3 hours the same batteries die if I watch a movie on s3, it goes from 100 to 10.
(on airplane mode. lowest brightness, maximum wakelocks restricted, google services frozen, Maximum CPU frequency down to 400mhz settings enabled)
if I use it just for calls and moderate messaging, it last 12 hrs.
on airplane and standby mode together, it goes on for 24 days.
weird thing is If the device goes below 30% battery and I plug in the AC charger, and use the phone, the battery would still be discharging instead of charging.
on safe mode, the battery will neither go up nor go down, no matter how long I keep using it while connected on charger, it would stay at the same 10%.
while if I plug in for charging while it's above 30%, and keep using it, it would be charging normally.
sometimes the s3 would treat the AC charger as a Normal USB cable, while if I remove and put it back again, it would show me charging/AC.
Now going through this post
"There is an "AC charger level" (set around 1000 mA), an "USB level" (set around 500 mA since USB1/2 standard does specify that) and a 3rd "low level / safety level" which seems to be around 50-100 mA."
Great find. actually. what I conclude from this post and in my case, the s3 while it goes below 30% it fails to charge/ or chooses not to charge on "AC charger level" and would always choose the "2nd USB level" or the "third low level", resulting in drain while using the device at the same time, while if left idle it would slowly charge on the 2nd and 3rd level until 30% then moving on to the actual AC charger level at 1000.
this issue I guess can be sorted out with some kernel side changes.
perhaps setting a lower Maximum boot CPU frequency (1000mhz?) and a lower default GPU frequency.(this can also sort out few heating issues) and lower default brightness level as well (or maybe not, it's just a hunch and I am no master myself.)
Anyways thanks for the useful input.