Charging aux battery in back of van (1 Viewer)

[O'Shell]

Greeting Mudders!
I have been searching around for some answers and the internet or my searching ability has failed me. Mud never has..
I am planning a month long road trip through Mexico in a Honda Odyssey and am doing part time camping and part time AirBnB.
I bought a cheap 12v thermometric cooler to keep cold drinks and some food. I know these have a high amp draw and was trying to figure out a way to power it while the engine is off.
I have a deep cycle 255 ah battery I was thinking of putting in a box in the back next to the cooler OR if you all feel it shouldn't be in the passenger compartment I could build a hitch mount for the box as I do have a hitch on the back and can weld fairly well.
MY question is with that set up how can I charge my aux battery in the back while the engine is running?
Is there some sort of cigarette lighter charger? (have an outlet in the back)
If not and I need bigger wires what kinda of isolater and size wires would I need to do the job of charging the battery up while I drive?

Thank you mud brothers!

 

[Bogo]

You may want to look over here first Power Systems This is something people often ask about. BTW, those peltier junction coolers are poor, and will only maintain 30 to 35 F lower than ambient. They really aren't good enough for perishables unless the temp is down in the 70s or lower. Go with a 5+ day type ice cooler, or get a compressor refrigerator.

 

[loosechange]

I don't know where you live because I have not looked at your profile but where I live we have a company called interstate batteries, they sell an isolator that will charge both batteries while keeping them separated which means that your number to auxiliary battery will never connect to the starter battery there certain reasons people get different isolators that's the one I have for my FJ40 ...extremely simple instructions to hook it up and it's only like 66 bucks it will charge your aux battery and your main battery your six battery will run the compressor... the only issue is your alternator needs to keep up with the power that that sux battery is drawing to keep your fridge running. Interstate batteries on the web and you can order them but just mostly any diode type isolator I guess with work

 

[Marine7]

Why don’t you just wire it in parallel? You only need welding wire to run to the back..... + to +, - to -, easy as that!

 

[mano002]

Does your van have a 7pin trailer plug on the back? Just wire up a plug that only has the trailer charging circuit and ground.