JCribb
Old Army truck mechanic
I sold one dual battery kit and unfortunately the person never sent me pics of his kit installed. I have made plenty of kits for my off road club and even with a ***** on there trucks very few needed 2 battery's unless you are running a ton of lights or other stuff. If you turn off the radio and keep your engine reved up you should be good.
Okay even with having electric fans and amp wiring? I bought the largest battery that would fit which is a duralast 800/1000 battery with the intent of running just one battery to power all my stuff. I just wasn't sure of the threshold where the second battery comes into play.