[Stroken n Smoken]

Thought I would check with you guys before I just pick up a new alternater, this morning after I drove to work I noticed my battery light is flickering at an idol, rev it just a couple hundered rpm and it goes out. About a month ago I installed 2 new 1000 cca batteries because I was having starting problems I had the alternator checked then and they said it was ok, but I did notice some brown soot, for lack of a better term on the alternater, I just wonder if I ran it too long with the crappy batteries and took the alt. out. I have a 99.5 7.3 psd. Thanks again for your help! :burnout