Yeah, 6 ga is plenty. I was just wondering if it needs to be that heavy. The disconnect I mentioned would be between the batteries and would do the same thing you are talking about. I do understand what you are talking about with the starting battery being drained by the tm battery. The reason I don't want to put another battery in for the tm is that this is not a large boat and I don't want any more weight ...especially up front. It seems like I may have read that for just a common ground 16 ga is adequate. After all, it would not be carrying any current. Thanks for your input.