I have one cranking battery for my motor and two deep cycle for my trolling motor. I would like to hook another battery to my cranking so Ill have more running time on my live wells and fish finder. Do I hook up the positive to the negitive or positive to positive? Do I hook up a deep cycle or cranking battery? After a long day of fishing the aireator shows signs of weakness and when it kicks on my graph fades in and out. I think it is to much draw on that one battery. Can anyone help?