dog box wiring

I have an extra battery under the hood with a battery isolator switch. Battery charges from alternator but accessories only run from that battery leaving truck starting battery at full stage. I have fan, pressurized water and airing lights that work on that battery.

Mine only has 1 battery under the hood and F250 is gas not diesel. I was thinking of adding a second battery in the bed but want sure if someone had come up with a better idea or plan.

Rich

I have a battery isolator and an extra battery up under the hood that just runs the box. Trust me it’s great. I ran 8 gauge wire back to the box.

As for wiring you can run a line directly to the + terminal on the battery, or tie into a positive wire on the trailer bundle. Key is to make sure you have a solid ground.
I run two fans in my topper. Also have interior and airing lights and pressurized water. I routinely run the fans all night when parked and have never exhausted the truck battery. And that was on a Chevy 1500 gasser as well the current F150 diesel.