Brand new battery dies quickly

Certainly the furnace is a big current draw. If you are running the refrig on electricity, either off 12v or with an inverter that will also be a big current drain.

Part of the problem may be that the battery does not get recharged. An '06 RV probably has a single stage converter that only charges the battery at a very slow rate, in the 3-4 Amp range. It can take a long time to fully recharge the battery.

Your tow vehicle will not fully charge a depleted battery. Get a generator. Even the small suitcase sized ones will run the converter to charge the batteries.

red31 wrote:
Fully charge the battery.

That's what I wonder. The furnace is the biggest draw of those mentioned, but shouldn't kill a fully charged battery in just one nights use.

Yup, furnace will take a battery out overnight with all the other items that require DC voltage. Changing to LED lighting 4 years ago really helped us cut down on consumption of our 12 volt reserves. Depending on your converter it could take sometime running the generator, even after running 2-3 hours you may be nowhere near fully charged, the poor battery gets drained even further down the next night. If your battery is not a true deep cycle it will certainly meet an early demise under this scenario.

If you camp off the power grid often you need to have at least a couple of fully charged batteries, a converter capable of delivering multi-phase charging, and some solar to help get the batteries further charged after running generator. Enough solar along with good weather conditions and the genny may not be needed for charging, being used primarily for powering heavy AC loads such as convection microwave and air conditioner. We use a pure sinewave inverter to power entertainment electronics or charge our portable devices.

Do you have a 3 way fridge? If so make sure it IS NOT on the DC setting. They suck lots of current on DC and will run down your battery overnight.

My furnace would not run down even a wimpy battery in one night.

Fully charge the battery.

You need to learn about 12v power consumption.

It is + - 100F in Pasadena as we speak.
More likely on + side
You need to put ammeter on the battery and start pulling the fuses one at the time.

Furnace is the only thing you said that would do that. How cold was it? What brand/type of battery did you put in?

Most people don't dry camp with just one battery.

Your furnace is the culprit. To run it all night you need a good-size battery bank. Best thing to do is get the place warm, get everyone plenty of blankets, and leave the furnace set as low as possible.