Furnace while boondocking.

[RoyBell]

For a 33' travel trailer, how much battery usage can I expect from the furnace? They are calling for low 40s over night and the women like it warm. The only site left was no electric so I booked it. I have 2 4 year old 12v batteries and led lamps inside.

I borrowed a small 2KW Honda inverter generator from a vendor to charge it up without the racket of my bigger unit during the day, but don't think I should run it during the night. It's a pretty quiet unit but you can still hear it running.

Is it safe to assume I can get through the night off battery power? I know they make small propane heaters but it's pretty rare to get stuck camping without power so I don't think it's money well spent in our case. If I can get one night and charge in the am for the next night I think it should be fine.

[CavemanCharlie]

Another thing you could have done was to have baked some cookies or something in the oven before going to bed. The residual left over heat would have helped to keep your furnaces from kicking in as quickly the first time.

[Vintage465]

Another way to "prep" for the night is to use a Mr. Heater Buddy or Big Buddy heater and warm the trailer up nice and toasty before calling it a night. Turn them off when it's nice and warm and set the 'stat for 55-ish for the trailer furnace and go nighty-night.

[time2roll]

Does your voltmeter ever go to 14.2+ volts when charging? Good chance those batteries were chronically undercharged by a fixed voltage converter.

[opnspaces]

Well you guys survived the trip which is what matters. It's even better that you were able to get the furnace running for the second night.

Unless you specifically asked for a true deep cycle battery when purchasing, I can almost guarantee you that the batteries are the standard hybrid 12 batteries that you can get at Walmart, Napa, Autozone,or Camping World. That's not necessarily a bad thing, they just aren't as robust as a true deep cycle.

As you stated, your batteries are old you might want to consider replacing them soon. But since you stated that it is rare to not have power I would replace them with the same basic batteries. If you were going to do more frequent dry camping you might want to consider switching to 6 volt batteries. But in your case I think that would be a bit extreme.

With decent batteries you can typically count on one night of furnace per battery, unless it's extremely cold. So if yours were newer you would have been fine.

[azrving]

Just checking but have you checked the electrolyte level if the battery does have caps on top?

[RoyBell]

Actually, I am not even sure what's in there because the camper place did it. I will check when I get home to see what it is.

[Jay_Coe]

Bobbo wrote:

RoyBell wrote:
They are not standard 12v batteries, they are marine/deep cycle batteries. Just getting towards the end of their life.

A marine/deep cycle battery is a hybrid battery. It does either starting duty or house duty. It does neither well.

That's a blanket statement that like most generalizations, isn't always accurate. Marine batteries are available in starting, hybrid and true deep cycle. Yes, the marine "deep cycle" batteries at Walmart and Costco are hybrids, but true deep cycle marine batteries are also available.

[Bobbo]

RoyBell wrote:
They are not standard 12v batteries, they are marine/deep cycle batteries. Just getting towards the end of their life.

A marine/deep cycle battery is a hybrid battery. It does either starting duty or house duty. It does neither well.

[azrving]

RoyBell wrote:
They are not standard 12v batteries, they are marine/deep cycle batteries. Just getting towards the end of their life.

Those rv marine are not true deep cycle batteries. NO, they are not standard batteries like a vehicle starting battery but they are not deep cycle no matter what they put on the label. THIS is a real 12 volt deep cycle. $225 vs $82.00

Have you ever checked the SG?

[RoyBell]

They are not standard 12v batteries, they are marine/deep cycle batteries. Just getting towards the end of their life.

[azrving]

50 aint guna work with my wife. More like 65 is what we like. You are starting out with minimal battery. There is nothing wrong with dual purpose 12 volt batteries but they arent GC2 or true deep cycle 12 volt. You have to start out in top shape. You basically have enough power in two 12's if they are in good shape and the specific gravity is UP. Have you ever checked the gravity? You can charge for X time and see high voltages but you may not be actually charged all the way.

The specific gravity will tell you what is really going on with the battery and show diffwerences in cell gravity. You also need to look at your charging system. If it's only doing 13.6 at the converter it may only have 13.5 or 13.4 at the batteries. Ann upgraded converter will get 14.4 v or even up to 14.8. Having a meanwell power supply is also handy for equalizing. Your battery bank is your cash in the bank, your energy use is withdrawals and your charging capability is your income. You also have to pay the banker for battery resistance and system losses.

[RoyBell]

Well, First night was interesting. Charged up the batteries and the CO alarm kept going off when running the furnace on batteries. I opened the windows and after the 3rd time I shut the furnace off.

In the am it was about 50 in the camper. Not terrible, not chilly nonetheless. The women were not amused. I checked out the detector in the morning and realized it was being set off from low voltage. Green/Red/Green is low voltage. Red flashing is CO detection.

I had installed a digital volt meter years back so I could watch voltages. While the furnace was running under battery power it dropped to 11.7 volts. Once it shut off the voltage would go back up. I am guessing prolonged load was enough to set the alarm off because it wasn’t instant.

On the second night I disconnected the alarm, left the windows cracked and set it for 65. I have a battery powered alarm that I left intact. Heater ran all night no problem. I doubt I could had gotten 2 nights without charging the battery.

[ksg5000]

Your close to the end of life of the batteries and if you have generator I wouldn't sweat it. Worse case scenario - your furnace shuts down in the middle of the night and you have to wait until morning to start up the generator, recharge the batteries and consider buying new ones. Ain't the end of the World. Odds are pretty good you won't have any problems if you recharge the batteries every day. NBD

[Bobbo]

When boondocking, we put the furnace thermostat on 50 degrees and sleep under quilts. We have a pair 12v group 27 batteries (they have more capacity) and get 2 nights. If we have the furnace thermostat set on 60 degrees or above, we don't make it through the first night.

[YC_1]

It will take about 2 hours in the morning and two in the evening using the generator and your onboard charger. Do not try to use the small charging cable from the generator if it has one. They often put out only 8-10 amps.

If your generator has the ecomode it will run on high and you can listen to it go to the slow mode as the batteries get charged.

If your lights inside are not led and you have an inverter for entertainment devices you could be stretching two batteries to their limits assuming they are in decent contition to begin with.

Do not rely on some led panel. You need to get a voltmeter on the batteries before and after as suggested.

A furnace can draw 6-8 amps and drag down batteries quickly if it is cold.