I have had this Trojan deep cycle battery for quite a few years. Used it with my Evinrude 85 and now with the Bearcat. This is the first time I've seen this but when I pulled the battery yesterday the positive terminal was blackened. I was able to wire brush it off but any ideas what might cause this.
Now that's a new one. I thought I had heard of everything that could go wrong with a battery, but this is new. Since the battery is quite old (battery life is usually 5-7 years) I would take it to an auto parts store, battery seller, or garage and have it tested to see what it's condition is. Obviously something is going on but I don't have a clue.
Well, after Googling my fingers off and some input from another forum it appears the the black coating on the positive battery terminal is lead oxide. The cause: two thoughts were leaking of hydrogen gas or some sort of interaction with the sulfuric acid. I did have some liquid on the sides of the battery (possibly I topped off too much before I put it on the charger) so I cleaned the entire case with baking soda solution which also allowed me to check for any cracks. After a couple of days the terminals still look clean. I did notice a small bubbling on top of one of the covers which could indicate a bit of leakage. Don't know if that is normal or if it has a crack. I'll keep my eye on it.....from a distance of course.
That's all I know, hope it's helpful to some.