positive battery terminal turns black

[ivansgreat]

NM5K My lights will flicker if I turn the truck on with the lights already on. As for the regulator, I just had a hunch that it might not be working properly. The problem with the truck wanting to turn off when I came to a stop is fixed now. I think the carburetor was a little clogged up. So, now the only problem is this blackening terminal. I've replaced the cable but it still turns black along with the terminal. It could just be the battery that's messed up, or a bad ground as somes of y'all have said.