If you are having charging issues like I am on the Galaxy S3, here is a solution, with this app to confirm your tests
Found this thread last night and read right through and found some interesting points which I'll let you read through.
Main point from the thread is Samsung cables and Samsung wall chargers suck together. Except in some lucky cases, like my girlfriends S3 which has never had an issue.
Basically I could leave my phone on charge over night (varying from 6-8 hours) and only gain 20%, if I was lucky, and had Wifi off.
Since swapping out cables and checking the current with GCC till I had the highest current, I easily went from 60% to 100% in just over an hour this morning.
That is with Wifi on and no special apps like DS Battery Saver, which I intially downloaded to stop the crazy discharge on this phone so I didn't have to leave it in a corner charging for 2 days to get back to 100%.
Seriously, download this app and have a good read right through the thread. It's only 23 pages.
A lot of good points and helpful tips such as tweaking the current level with STweaks with a kernal that allows that, and what cables to buy to replace your official Sammy one.
I recommend sticking to swapping out cables, especially if you aren't too technical like myself, as people have warned that tweaking the current could harm your battery...
Helped me, will definitely help you!