Optima battery??..

I think they are bad-*** enough to not drop voltage when fans kick in. Are these turning on without alternator input?
I don't think so... The alternator is working.. I think it's like a 64 amp or something?... It's just a cheap parts store alternator... I've looked at upgrading the alternator as well but really when you get into the 80 and 100 amp alternators they seem not so great at low RPMs anyways..