I have read through the previous posts and seen a lot of responses referencing new cables, outlets, batteries etc. In my case, none of them were the issue...it was the Charge/USB port, and based on my experience I would suggest that many others have the same problem. (If a new cable or battery does not remedy the issue, I would suggest you consider it to be your port as well.)
I have an S3 that after 9 months began to charge erratically and quickly deteriorated to the point where it would lose charge when properly connected to a charging cable. I took it to Sprint, whose technician said it was a configuration issue (obviously not the case) and suggested it was due to using the "wifi optimizer". I tried to explain the phone holds its charge fine so it is not a config or battery issue - but a charge issue. Since they didnt help I was told to try new accessories and then send to the manufacturer. So, I tried several cables (Blackberry, Samsung etc) and none had a different result. So ultimately I sent it to Samsung for repair. After about a week, this is the response I got back in an email (I still have yet to receive the phone back):
Please view additional information below for more details.
Original Problem:
ACCESSORY - CHARGER ISSUES - WILL NOT CHARGE
Problem found:
GROSS ELECTROMECH DAMAGE-ABUSE
Solution:
BER
If you have any additional questions, please call us at 1-888-987-4357 and reference Ticket Number: 412XXXXXXX.
The "BER" referenced above means "beyond economic repair". So basically the problem was identified as being "gross abuse" of the charge/usb port in my phone - and specifically I was told by Advanced Support that it was an issue where the port is soldered to the motherboard. My phone was in a more than adequate protective case (w/ a port cover) and it had no water damage, nor was it dropped. Therefore by "gross abuse" it was concluded that I must of used the charger(s) too much and possibly wiggled it causing the damage. Samsung said it voided my warranty, and this repair is not covered. All the symptoms in previous threads were present on my phone. I steadily lost charging capabilities (not a sudden loss which may suggest I dropped it etc.). My phone was in perfect condition (no scratches etc). I was also told that if it was a defective part/device, it would be evident within 30 days (that was a new one to me). Regardless, I am being sent back a phone that was not repaired, and told that Samsung WILL NOT honor the warranty. I sense that as this problem increased, the cost incurred to repair became too much so Samsung is now returning them back to the owner with BER. This is enough for me to look elsewhere for all future technology purchases, but I am not dumb enough to dispose of an otherwise perfect phone. Looks like the options now are wireless charging pad (Qi technology) or buy a battery charger and spare battery.
This has been a very frustrating process, as I have spent hours on the phone with Samsung talking (arguing

) that my use of the phone was by no means "gross abuse". I cannot comprehend how charging a phone too much could be deemed abuse.
Has anyone had success sending their S3 back to Samsung for a Charge Port issue and actually gotten them to fix/replace it?