Furnace all night?

[Gtx Eng]

The great experiment begins! Harvest Hosting at a winery Texas Hill Country. Expect temperatures to be about freezing tonight. Left the generator at home. So my wife and I decided we are going to see if the two house batteries installed by the dealership will see us through the night.

Furnace pulls 7.5a on 12vdc. Batteries are twin Continental with reserve rating of 120 minutes each. Assume a 50pct capacity reduction due to cold batteries, the trick will be if I can count on a 50pct or less duty cycle on the furnace. As I said, and experiment...

[GCinSC2]

Curious, Amp hour rating of batteries ?

[nvestysly]

Yes, it will be an experiment. Be sure to post your results.

My suggestion is to dress is your warmest night-time attire, heap on a heavy comforter or other blankets, use flannel sheets and don't turn the furnace any warmer than 50 or 60. I feel confident your batteries are not up to the task of maintaining your trailer at a comfortable temperature. Running the batteries too far down will have a detrimental impact.

We installed an Olympic catalytic heater for these types of situations. We haven't used it much but it certainly takes the chill off and keeps the duty cycle of the furnace to a minimum.

Another thing to consider is the fact that your batteries will not re-charge much when traveling down the road if your only charging is via the 7-way connector. We don't have solar and don't really know if we want it but we needed a way to recharge our batteries while driving. We posted a thread on our upgrade HERE. It may be worth reading.

[Gtx Eng]

So here's an update, wide awake as normal at 0530. Batteries showing 11.9v resting and 11.7v when furnace cycles on. Tstat was set to 60 all night, I slept as normal, wife bundled up, apparently too much. Furnace maintained interior at 60 with no problem. Outside conditions are clear sky and high 30's.

What i didn't figure into my calculations was that I had a CPAP machine running on the inverter circuit and there would be dishes and 2 showers taken, requiring the water pump.

All in all, very successful. And I was surprised the dealership batteries worked as well as they did.

Photo this morning. Texas Hill Country stars.

[Shiny16]

I’m not too sure most people on here would be comfortable with their batteries dropping to 11.9 volts.

[lsbrodsky]

I do not know why you think this is good? You are killing your batteries, maybe already have. You should not discharge below 12.2 resting for a lead acid battery. The consequence is reduced capacity, which will reduce more and more. They simply aren't designed to discharge that much, unless I missed that you installed Lithium cells, which can be discharged down to 10% without any consequences.
Larry

[Gtx Eng]

So, now for the mini rant....

We bought our '21 FC from the dealership in our region. This is no small investment. And Airstream puts the installation of the house batteries on to the dealerships, correct?

Our trailer came with possibly the cheapest batteries possible. Listing $82 brand new at some sources. They aren't even single purpose RV house batteries - they are Marine combination starting batteries! Continental TM-24.

To answer your AH question, the batteries don't even carry that rating. They do list a 120 Reserve Capacity, meaning that at ideal temperature, they can supply 25 amps for 120 minutes until depleted to 10.6v (much deeper discharged than I'm comfortable with). So a calculated rating of 50 AH?

Originally Posted by GCinSC2

Curious, Amp hour rating of batteries ?

[OTRA15]

Originally Posted by lsbrodsky

I do not know why you think this is good? You are killing your batteries, maybe already have. You should not discharge below 12.2 resting for a lead acid battery. The consequence is reduced capacity, which will reduce more and more. They simply aren't designed to discharge that much, unless I missed that you installed Lithium cells, which can be discharged down to 10% without any consequences.
Larry

Bingo!

. . . if Larry's assumptions are correct . . . significant damage already IMO . . . see battery level chart here:

http://www.batteriesnorthwest.com/batteryschool.cfm

[Gtx Eng]

Good only so far as they are carrying the trailer heating requirement overnight.

As cheap as the batteries are, I didn't expect them to do even that. And killing then we'll result in a careful selection and possible re-engineering off the house power system so we can effectively boondock without running a generator overnight.

Originally Posted by lsbrodsky

I do not know why you think this is good? You are killing your batteries, maybe already have. You should not discharge below 12.2 resting for a lead acid battery. The consequence is reduced capacity, which will reduce more and more. They simply aren't designed to discharge that much, unless I missed that you installed Lithium cells, which can be discharged down to 10% without any consequences.
Larry

[Gtx Eng]

Great link, thanks.

Using that voltage indication of charge, the house batteries were never charged beyond about 50pct. Days of 50A shore power and a 30 minute tow to a boondock showed batteries starting with 12.3v before any load was impressed on them.

Makes me wonder how the factory system charges batteries? Guess I'll break out my manual.

Originally Posted by OTRA15

Bingo!

. . . if Larry's assumptions are correct . . . significant damage already IMO . . . see battery level chart here:

http://www.batteriesnorthwest.com/batteryschool.cfm

[Shiny16]

I’d question my dealer as to why they installed a dual use battery. I thought they all came with a minimum of Interstate lead acid batteries.

On another note. Where is the thermostat located in your trailer?

[Gtx Eng]

Might do that.

Tstat is in the bedroom (forward).

Originally Posted by Shiny16

I’d question my dealer as to why they installed a dual use battery. I thought they all came with a minimum of Interstate lead acid batteries.

On another note. Where is the thermostat located in your trailer?

[Shiny16]

Originally Posted by Gtx Eng

Might do that.

Tstat is in the bedroom (forward).

I believe the furnace is also in the bedroom. I’m not sure if the furnace is ducted or not. You could close the curtain that separates the living space as well as the ducts outside of the bedroom. This way you are not heating the whole trailer all night. I do this with my 16 and it cut the furnace cycle time by probably 30 to 40%.

[ROBERT CROSS]

Call JC ask them directly which brand, style and capacity the trailer should have, I believe the 27 should have AGM's.
We had 2 Lifeline Group 27 AGM's for 11 Seasons before replacing with battle born Lithiums. The AGM's are still in good condition and doing service in the basement as sump pump back up.

With the CPAP requirement I would consider at least a 2 Lithium battery upgrade with remote monitor and a lithium compatible converter/charger upgrade.

We did the same DIY upgrade along with 2 Zamp 180w portable solar panels for less than $4k👍

Bob
🇺🇸

[lsbrodsky]

GTX,

It is not unusual for dealer to not know what they are doing with batteries and Airstreams have historically been delivered with depleted batteries. The new policy removes Airstream from the equation and places the responsibility on the dealers, who were the ones who let the batteries fail in the first place. I have seen car dealers run chargers around their lot and periodically charge the batteries. Ever seen that at an RV dealer?
You have defined a serious need for heat and CPAP and you have learned that using your trailer as is will not meet that need. Time to do some study and/or talk to experienced installers. There are lots of threads on the forum concerning upgrades like solar, better charging from the tow vehicle, batteries, and so on.
As you were warned, the furnace blower is a big DC load. You have to replace those amp-hours somehow, probably every day with lead acid batteries. The simple solution that many use is a small generator. But you could buy a Lithium power center and charge from that, depending on how many days you will boondock.
I went Lithium batteries 4 years ago with fixed and portable solar and did a similar experiment, although in Eastern shaded camping. I could only go 4 days, running the furnace only in the early morning to warm up, before I needed a generator charge.
Bottom line is that you are going to need to do some modifications.
Larry

[GCinSC2]

GTX,

We just had our first battery/generator outing and it was a learning experience. Monitoring the DCV and relating that to State of Charge was new info for me.

Many write ups, videos and website info but I printed off the East Penn Marine RV info chart.

https://www.eastpennmanufacturing.co...chure-0273.pdf

East Penn is a manufacturer of batteries.

Still learning but a new topic to learn about.

Gary

[brick1]

Your existing batteries are the wrong type, and are likely toast anyways, due to how low they were discharged. Replace with marine deep cycle, or upgrade.

[GettinAway]

Here’s what I did. I was continually reading threads like this that had me pretty apprehensive about running the furnace at night. We piled on the blankets, and ran the furnace in the morning while making coffee, so my lovely wife was comfortable when she got out from under the frosty sheets. Finally I said, enough is enough. I’m not going to switch to full hookup spots. We like Harvest Host or Boondocking in NF service CGs. I wanted to switch to lithium, but the more I read the more confused I became. My Dad was an electrical engineer, but I did not receive the engineering gene. I did not want to invest $10,000 in lithium batteries and solar panels. Some folks do, and that’s fine, but not for me. I bought two BB lithium batteries on cyber Monday. They supposedly are blemished, but I can’t find anything. I took my “situation” to an expert. A guy that does tons of solar and lithium upgrades, and AS lifts. He did the solar upgrade on the Lolo Honeymooners AS. I’m sure the video is easy to find. I bought a Renogy 200 watt (or amp whatever it is) portable solar panel from Amazon, that was dirt cheap as it had been returned to them. All the correct “stuff” is in my AS and truck to use, charge, maintain, and monitor lithium batteries. It didn’t break the bank.
This may not be the solution for GTX Eng (OP) because he seems more electrically capable than I am, but maybe someone else reading this needs help.
Send me a PM if you want to know who upgraded our AS. He did a great job.

[Gtx Eng]

Quick update -

First off, this was our first trip in an airstream, and the first trip my wife and I had ever made in an RV! We certainly learned a lot, and the feedback on this thread has been helpful.

Secondly, we really enjoyed the harvest host in Central Texas, landing in a small winery and just hanging out in the field was a great change.

So when I pulled out a camp, both voltage indicators, one for the inverter and the second backup on the water system, showed 11.6 volts. The truck does charge the batteries, but only weakly. I did an immediate check on cranking up the truck and plugging in the wiring harness and my battery voltage jumped from 11.6 to 12.3.

Stopping 30 minutes later for breakfast and day check on the system, the battery voltages were showing 12.7 volts but with the truck idling and charging. Turning off the truck and checking the voltage again shows 12.3 volts, which is what we started with when they were supposedly fully charged. I know that's a floating charge voltage that will burn off quickly when a load is impressed, but I'm having a hard time correlating the actual voltage readout to the true capacity of the battery.

Much to learn!

[gypsydad]

Originally Posted by Gtx Eng

The great experiment begins! Harvest Hosting at a winery Texas Hill Country. Expect temperatures to be about freezing tonight. Left the generator at home. So my wife and I decided we are going to see if the two house batteries installed by the dealership will see us through the night.

Furnace pulls 7.5a on 12vdc. Batteries are twin Continental with reserve rating of 120 minutes each. Assume a 50pct capacity reduction due to cold batteries, the trick will be if I can count on a 50pct or less duty cycle on the furnace. As I said, and experiment...Attachment 385269

We switched to Trojan T105's 6V's, 3 years ago and are very satisfied use model when boondocking. We also carry along a 80W suitecase PowerPro portable solar to augment. Difference is we also carry a generator along if/when needed. But, the 6V's we have are MUCH better then the 12V Interstates that come with the AS's, IMHO...without braking the bank like Li's can do!

(by the way, which winery are you at with HH's? We have not used our membership yet and are looking to get out in January.)