Adding Aux Battery: Is this how to do it?



Here's a diagram that I'm looking for comment on. The details are this:
2006 Tacoma w/ 130 amp alternator
Wired with a Marinco 3 pin plug from 4WC
1996 Northern Lite Camper with 7 pin

I want to add an aux battery and a separator.

1 - Do I need the Sure Power 200 amp separator or can I go with the 100? I thought my 4WC had the 100.
2 - The camper looks as though the ground is grounded to the propane line for the fridge. Is this standard?
3 - What gauge wire should I use?

and now for my incredible diagram!! (there is a fuse between the main battery and the Marinco I didn't draw in)

Electric Diagram.JPG


With a 130 amp alternator, it's unlikely that the line to the aux battery would ever see more than 100 amps... there will be a fair amount that's already spoken for by the vehicle's electronics such as computers, ignition system, etc. You could probably get away with the 100a model. Personally, I like to leave room for future upgrades like additional batteries and a bigger alternator. Then you'd want the bigger isolator I would think.

Your wire should be sized to handle the full load continuously. I wouldn't go thinner than 4awg.