Reason for a dual battery setup in my case. I have a Fenner snowplow pump and also many aux. lights. I have a 130 amp. alternator as well.

Here is my dual battery set up that I am going to use. I looked at battery isolators. They do a good job, but I decided to use the Cole-Hersee continious Duty solenoid. It only cost me 20.00 and I got welding cable 1/0 from a local welding supply company (free, shhh don't tell). All in all I have only 35.00 (less Battery) invested in this set up. Also when I bought the truck it had two battery trays.