" Adding HD Springs/200hr Battery Bank to '97F150 '78 Bethany Pickupper " this is the name of a post I have on this forum where I show how I fumbled through doing this exact thing. Basically just run the wire from the starter battery to a relay then back to the camper battery pack. There is a small wire to connect to the relay from the ignition circuit that will open and close the relay so you won't drain your starter battery when on the road. And a couple of grounds too.
I also show how made my own wire terminals out of some thick flexible copper tubing, its much cheaper this way.
I used 00 gauge wire, its less than a 10 foot run from the starter battery to the final ground. I charge both batteries in my camper pack by idling the truck for about 15-20 minutes. I have a stock 120amp alternator and use a cheap 200 amp inline fuse back by the battery pack. I probably over did it. I would think 4awg would be fine. I used the cheapest 200amp relay I could find on Amazon, so far so good on the relay. You can use an "add a circuit" from OReilley or AutoZone to tap your ignition circuit in the fuse box without having to cut any wires.
Check out the thread, it was easy enough to do and handy as hell. I got lots of pics. I'm glad I went this route before any other because it was the cheapest and very effective. I would still like to add solar but I definitely never "need" to.
I'm just killing time on here, thought this might help you if you haven't completed the project yet. So that's what I did. Good luck.
I also show how made my own wire terminals out of some thick flexible copper tubing, its much cheaper this way.
I used 00 gauge wire, its less than a 10 foot run from the starter battery to the final ground. I charge both batteries in my camper pack by idling the truck for about 15-20 minutes. I have a stock 120amp alternator and use a cheap 200 amp inline fuse back by the battery pack. I probably over did it. I would think 4awg would be fine. I used the cheapest 200amp relay I could find on Amazon, so far so good on the relay. You can use an "add a circuit" from OReilley or AutoZone to tap your ignition circuit in the fuse box without having to cut any wires.
Check out the thread, it was easy enough to do and handy as hell. I got lots of pics. I'm glad I went this route before any other because it was the cheapest and very effective. I would still like to add solar but I definitely never "need" to.
I'm just killing time on here, thought this might help you if you haven't completed the project yet. So that's what I did. Good luck.
