I need to add a battery disconnect onto my cranking battery as something is slowly draining it. I cant seem to find it either as I take all my electronics off the boat when not it use. So my question is do I hook the disconnect on the positive or negative side or does it matter? Reason I ask is a couple of machines that we have here at work have them on the positive side but have a truck that is on the negative side. I am assuming either side will work but want to make sure.