positive terminal turns black

[kman]

The positive on my battery turns black likes its Burt I run a 600 watts amp right from it could that be what's doing it it has me confused anyone know what it could be?

 

[srteach]

Lead turns black when it oxidizes. The terminals on the battery are made of lead. Oxidation can be caused by heat. Running 600 watts can heat the lead, especially if there is high resistance at the connection. That could be the answer.