I will be hooking up a second battery in my westy in the coming months. I have a battery isolator made by sure power model 24023a max amps 240. I took this off an ambulance that had an engine fire but all stuff in the back were fine. on the side of the isolator there is a diagram with a 1,A,E,2 representing the bolts on the top. What I need to know is this usefull for my battery connection and also what are the bolts on the top for. I imagine the 1 and two represent the batteries and the A represents the alternator but I do not know what the E is for. I also have several bosch 75 amp and 30 anmp relays, a solenoid, a cuople heavy duty diodes. Are any of these usable for this application?Thanks Patrick , Appin Ont, 85 westy