How long will single battery last with heater running?

philh wrote:
We may have our first opportunity to dry camp mid winter for one night. Do I stand a chance of surviving on a single deep cycle 12V battery, or should I just plan on buying my first i2000?

Depends on how much amp power is your furnace drawing and for how long..

I have Espar diesel heater that's probably the most efficient unit available and it discharged the battery only 20-25% down even at minus 20 C..but then I have two inches of rigid foam insulation everywhere in my small TC and double pane windows.

So cold can get a hermit to come knocking?

"WHY IS THERE NO @#$%^&! WATER"

"I'm sorry honey it musta froze last night"

"AGHH! NOW THE SINK IS LEAKING AND FROM UNDER THE CUPBOARDS TOO!"

Naive cold-weather camping is soooooo fun. At 0-Dark-Thirty in Zacatecas. Zacatecas, I was awakened by a neighbor. It was nine degrees F. We connected my 35' jumper cables to 2 20 footers of his sets and he he got his heater and lights back. I use an OLYMPIAN 8,000 BTU heater. In the morning, my amp hour meter registered -139 ampere hours. Some RV'ers need a keeper, but that comment does NOT apply to this thread :)

As others have said, it's going to depend, and your mileage may vary.

I've slept plenty comfy at 18-degrees outside with no heater. I had a nice sleeping bag and air mattress directly on the snow. I've also had a heater run multiple nights in a camper with one 12-volt battery.

My point is how warm do you want your camper and how warm do you want to be?

If you have a zero-degree bag you probably won't have to turn on the heater. If you're using bed sheets like you would at home, you're probably going to want it in the sixties or so in the camper/trailer. If it's fifty outside and your camper/trailer is well insulated, your heater won't run much. If it's 18-degrees outside you'll likely kill your battery right away.

So, my thought is if you're married, you should buy a Filson Mackinaw blanket and set the thermostat as low as it will go. Snuggle up close and know it's going to get cold. If it's just you, buy a Butler Bag and don't worry about turning on the furnace at all.

As for the OP, I'd buy the eu2000.

However, I would highly recommend going with two batteries, just because few places allow 24/7 generator running. Just one battery will get damaged if drawn over 50%, and even with a smaller vehicle, you are near that 50% SoC barrier.

I have seen heater controls and blowers draw 8-amps.

For 12-hours run time in very cold weather this is 96-amp hours.

You arrive. You shut off the key. The refrigerator is on gas. You use lights. How many amp hours is anyone's guess. How well insulated your rig is never mind how big is someone else's guess.

Your battery size and capacity is another contender for the Ouija Board. It's age, dogpiles on the quarterback.

I'll place a 5 to 1 bet with anyone that if your rig is NOT a camper nor less than 25' in length, the average temperature is 30 degrees or less from 6PM to 6AM, and you use the lights for 2+ hours the night before...

You are going to feel the cold feet of the DW shoving you out of bed at 4AM to a pitch black 45 degree rig.

philh wrote:
We may have our first opportunity to dry camp mid winter for one night. Do I stand a chance of surviving on a single deep cycle 12V battery, or should I just plan on buying my first i2000?

There's just not enough data here to answer. How many amp hours is the battery? How many amps does the furnace draw? What percentage of the time is the furnace running?

I have a small forced air unit which takes 3.5 amps when running. At night I set about 55-60 degrees trying to keep run time under 50% if battery charge is an issue. At least for me sleeping with plenty of covers isn't a hardship.

When I'm up is where I like the 70 degree temps. Sunny days can be quite cold and still be pretty warm inside with a little help from furnace. Extended cloudy cold days are the worst. No solar, lots of furnace. Good to have that generator then.

When batteries get cold they lose capacity, and I doubt you're going to be running a generator all night.

I love these "12 volt battery" question.

First: I suspect the answer is no, I'd add a 2nd one in parallel

Now: the problem with the question.
A single Group 24 is what 75 amp hours.
A fork lift battery is what, 1,000 amp hours or more.

Both are single 12 volt batteries I have used in days gone by.

Sounds like you are leaning towards buying a Honda EU2000 anyway, just buy it and not worry. you won't regret having it.