Hey guys, encountering a strange issue with charging my S3. Typically it's always charged pretty fast, 2-3 hours to reach 100% but recently however, it's started to SOMETIMES, charge really slow. I'm not sure whether it's an issue with the charger itself, whether it can wear out, cause my gf and sister been using it to charge their s3's, or whether it's a battery issue, or something worse.
Today seems to be the worse, i left it to charge at about 3am, it was at 10% charge and when i woke at like 9ish, it was only about 40%!!
So, I tried changing the power socket (trying anything that would make a diff), and it started charging fast again.. up to 80%..then it stopped! and even started discharging eventhough it was still plugged in.
Warranty has run out, so am needing some advice, whether it's a battery problem, or a charger cable/charger problem or just send it back to Samsung. Any insight and advice would be appreciated. Thank you.
Oh, and it's discharging unnaturally fast now, gone down from 80 to 70% in 20 mins!

Without me doing anything with it.
Use Galaxy Charging Current to check your charging rate... you should get 999/ 1000 reading..