Beats me, as I know it was not the cable or batteries (used cables and batteries I know worked from other controllers of mine). Something was up with the charge port itself. I know i'll end up getting another one at some point, as i'm down to one controller right now.
I've got a SF IV pad and bought it because I know the d-pad is an a++ one. I'm just hoping that the silver controller one is a decent enough step up from the shitty one the controllers currently have.