Either way, you can't leave the fridge on 12V power without some sort of power augmentation for terribly long. If you are going to be parked for more than 5 or 6 hours, I would recommend switching to propane for the duration.

Originally posted by offgrid Its legal except in a few tunnels/bridges on the East Coast and in Texas. I happen to go over one of these frequently so I tend to run on electric while towing so I don't have to stop and switch over for the bridge. But I'm fine with running on propane otherwise.

I did not know about Texas. What bridge there prohibits propane? That does not make a lot of sense since a bridge is unlikely to be able to have a build-up of propane in sufficient quantity to enable combustion.

The one principle is that propane is heavier than air so if there is a leak, it would tend to go to the lowest point. In Baltimore and NYC, the tunnels are under rivers so the lowest point is in the middle of the tunnel. The Chesapeake Bay Bridge/Tunnel is the same. Tunnels through mountains are sloped so there is not a low point in the tunnel so there is no risk of propane accumulation inside the tunnel.

We have had to go around Baltimore's tunnels since it was listed as a flat-out prohibition of propane regardless of whether the tank valve was shut or not. Personally, I run our refrigerator on propane whenever it is not plugged in to shore power. That is because I found that our dual 6V batteries were not getting adequately charged if the refrigerator was being run on battery. Running a dedicated charging line from the battery of the tow vehicle to the trailer might make a difference, but I've not had any problems running with propane since I put the screens on the refrigerator vents to keep the wasps out.

But, there is an inconvenient side to the water heater when using the electric heat element.  If that element ever heats up with an empty water heater tank, it will last about 30 seconds before it's burned up.  So, it is a good practice to keep it turned off when you don't want to use electric energy to heat your water heater.  There are two switches that control the electric heat element.  One is on the back side of the water heater [outside] under some gas tubing and a little hard to reach.  It's a black toggle switch with a little hole on the side where you can put a pin or cotter key in it to prevent accidental movement.  The other switch is in your AC power circuit board panel.  It's the AC breaker that controls current to the water heater.  Check the archives and you'll find a number of discussions about this topic and also a very clear foto posted by marwayne showing the location of the switch on the back of the water heater.

Best of luck with your pod and enjoy camping.

Its legal except in a few tunnels/bridges on the East Coast and in Texas. I happen to go over one of these frequently so I tend to run on electric while towing so I don't have to stop and switch over for the bridge. But I'm fine with running on propane otherwise.

Up to you what you do. 

Depending on how much you use your stove, water heater, and furnace you could well need a new propane cylinder within 3 weeks. No big deal, just start checking it after about the first week or so and do a swap at most any convenience store, hardware store, or Wally World. You can pour warm water over the tank and feel where the tank temp changes to estimate how much propane you have left. 

Enjoy your trip!

Also first long trip. We will be gone about 3 weeks. While driving, most of the time, I intend on using propane to run fridg, any problem doing that ? And will a full propane tank last that whole time ? I will use electric at other overnights...almost all have electric except the 3 nights in Cal.

Anyone have any suggestions ?

I know the parks have no electric, but I think a battery will last 3 days, with propane ... or is a 2nd battery recommended ?