Dual Battery Design for a Noob - Step by Step run through (hopefully)

[suprarx7nut]

My 2cents is that you don't really need to make it overly complicated, especially for your use case. I run the super simple dual battery system, that is a solenoid connected to the ignition, so that if it is in acc or on, the two batteries are connected, if it is off, they are separate and everything runs off the "house" battery and the "start" battery is isolated. I use AGM batteries with 0 gauge connecting them and 0 gauge to the winch. I believe it is 8 gauge to the rear, including for the fridge. It is a relatively long run, so there would be power loss with lower gauges. I also use a voltage booster in the ALT fuse.

SupraRX7 is right that the lifepo4 batteries are state of the art, but it's ok to not go that way. You probably really don't need a dual battery at all, honestly, if you're not running a fridge or some kind of ongoing draw. The winch is super power hungry, but you're not using that for a really long time (hopefully) and the truck is running during use (although alternators are actually way less efficient than people realize). I always have a NOCO GB70 around for jump starting, so jumping from the second battery isn't really needed.

If I was doing it again, I would only change to add a true battery monitor/isolator (national luna etc).

+1 on the jump pack. The dual battery jumping concept barely works under the best circumstances. A $100 jump pack is much better, IMO.

 

[willyroo]

Especially the option of charging via the alternator while driving.

An electronic isolator is a "set and forget" option. It ensures the house (ie truck) battery is charged first, and once charged, it then switches to the 2nd battery (or in our case the 12V supply to the camper trailer).

Here's the isolator "on" - so sending charge to the 2nd battery:

And once the house battery needs charging (drops below about 12.3V), the isolator switches off and all alternator current goes to the house battery.