Wiring "house" batteries and a Fridge

[Tiger Lair]

I'm planning for an extended off road trip (hopefully 2 months) in a Ford Ranger FX4 and need help on wiring a 12v fridge and the 2 deep cell batteries I'll carry to power it overnite and when not actually driving.  The plan is to wire the two 35ah batteries directly to the truck's battery/alternator and power the fridge (42-36 watt) via the cig. lighter when running and via the batteries when parked.  But it has dawned on me that it would be simpler to wire the fridge to the batteries so that the direct wiring is charging the batteries and powering the fridge simultaneously.  Is there something I'm missing here?  And would 10awg wires handle that much amperage? 
Any thoughts and assistance is greatly appreciated.
Tiger Lair

ps  I do intend to have a shutoff between the truck battery and the house batteries to prevent the house batteries from draining the truck battery when not running.

 

[TMG51]

If your alternator charges your house battery, and your house battery can't drain your engine battery, I would say you are good to wire the fridge up to the house battery...with fuse.

 

[Seraphim]

Send sternwake a pm about this

 

[LeeRevell]

Two 35AH batteries? Taking them down only fifty percent as necessary gives you only 35AH a day for use. Be sure you know how much power the fridge will draw per day.

 

[SternWake]

Sternwake has already written thousands of words on this subject which would be revealed in the simplest of searches

 

[akrvbob]

I didn't really follow your question. But you have a good plan. Run a 4 gauge cable from the starting battery to the house batteries to charge them while you drive. You'll want a way to disconnect them so you don't run the starting battery down and the best choice is a continuous duty solenoid but a simple on-off switch will do the trick.

Run the fridge off the cars cig lighter while driving and switch to the house battery when not.

70 ah is not much of a battery but under ideal conditions should work.
Bob

 

[highdesertranger]

yeah 70ah isn't much. doesn't give you a lot of reserve in case you are sitting without the engine running for a couple of days. highdesertranger