Propane Fridge Draining Batteries?

MM2 · 06-13-2021, 12:03 PM

We have just returned from our first long trip in our new 2020 Vista. We were mostly camping in unserviced sites, and kept the AC/LP absorption fridge running on propane. We found that the batteries were being depleted at an alarming rate and narrowed the culprit down to the fridge.

Only found reference to AC fridges running on inverters, or DC models, but we've seen mention of the need to monitor batteries with a unit like a Victron or Trimetric (I hate the "step gauge" type of installed monitors anyway, I call them "idiot lights"), so that's on the list, as is a possible solar panel array (our unit isn't prewired though).

But should the fridge really consume so much battery when running on propane? The problem seemed to be getting worse over our month-long trip, to the point we had to run the gennie morning and evening every day. And that really put a crimp in our hiking opportunities with most campgrounds limiting the generator usage times.

Thanks for any comments and tips from all you experienced folks.

DavidM · 06-13-2021, 12:25 PM

My absorption fridge uses 0.7 amps when the burner is on and about 0.2 amps when off. It averages 50% on in coolish days so it averages about 10 amp hours daily. I suspect you are using a lot more than that.

If you are using more, maybe you have a three way fridge: propane, AC and DC and you have set it to DC. That pulls a lot, probably 10 amps DC when on and it is on most of the time. Reset it to propane only and it should go back to the numbers above.

Another thing that might be drawing unexpected current even if set to propane only is the LP switch if so equipped. These draw almost an amp while on and you have to leave it on 24/7 when the fridge is on propane. There are ways to rig up a resistor and capacitor to drop it to about 0.2 amps or less. Google it to find out how.

If you do a lot of dry camping, install a shunt based battery monitor such as the Victron for about $220, Renogy for about $85 and this one for $45: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

A shunt based battery monitor will let you watch actual DC amp and amp hour usage.

David

backtrack15 · 06-13-2021, 12:31 PM

I believe the most common usage numbers while on propane are in the 0.8-1.5 amps range (12V DC). How much current was it using?

It could also be an issue with your batteries. Are they in good condition?

MM2 · 06-13-2021, 01:34 PM

Quote:

Originally Posted by DavidM

My absorption fridge uses 0.7 amps when the burner is on and about 0.2 amps when off. It averages 50% on in coolish days so it averages about 10 amp hours daily. I suspect you are using a lot more than that.

I found a sticker in it that says it uses .95 amps or 11 watts on DC. Our batteries are Napa 8240N, which Mr. Google tells me isn't a true deep cycle battery but a hybrid. Specs say 120 minutes RC, so I figure that equates to only 50 amp hours. Times 2 should be 100? So even firing 100% of the time the fridge should drain them in 50 hours? These numbers would be consistent with our experience I guess, given that the fridge packs it in before the batteries die.

I think that I better add better batteries to the shopping list.

Quote:

Originally Posted by DavidM

If you are using more, maybe you have a three way fridge

Ours is definitely only a two way. Norcold N7XRT.

Quote:

Originally Posted by DavidM

Another thing that might be drawing unexpected current even if set to propane only is the LP switch if so equipped.

I don't think we have one, the only propane control is the valve on the tank.

Quote:

Originally Posted by DavidM

If you do a lot of dry camping, install a shunt based battery monitor such as...

We will be, so these are great suggestions, thanks.

MM2 · 06-13-2021, 01:37 PM

Quote:

Originally Posted by backtrack15

I believe the most common usage numbers while on propane are in the 0.8-1.5 amps range (12V DC). How much current was it using?

It could also be an issue with your batteries. Are they in good condition?

I can't measure directly (yet), but see my sticker values in my reply to DavidM. The batteries are brand new, and I had them measured at a Napa store en route after the problem surfaced. They passed with flying colours.

Elkman · 06-13-2021, 02:22 PM

My 2021 Navion has DC only fridge and not a 3-way that would use propane and so the power consumption is very very high. Even with the 200W of solar on the roof the factory lead acid batteries were at 50% SOC after only two days and that was with the freezer at +15 degrees and the refrigerator at +37 degrees and no opening of the doors during this period.

I replaced the factory batteries with lithium phosphate ones so I can take them down to 10% SOC with no worries. The lithium phosphate recharge 3x as fast when I run the generator to get them back above 95% SOC every other day.

The new Navion is meant for use with shore power and not for dry camping unless you don't mind using the generator all the time and carrying extra diesel fuel for it.

CoolBreeze · 06-14-2021, 10:08 AM

Some Dometic units have heater coils that run around the perimeter of the freezer to keep condensation down around the door seal area. I disconnected that circuit on my previous RV's fridge and didn't have any problems.

https://www.irv2.com/forums/f54/dome...ls-291269.html

NeilV · 06-27-2021, 08:53 PM

Quote:

Originally Posted by MM2

We have just returned from our first long trip in our new 2020 Vista. We were mostly camping in unserviced sites, and kept the AC/LP absorption fridge running on propane. We found that the batteries were being depleted at an alarming rate and narrowed the culprit down to the fridge.

Only found reference to AC fridges running on inverters, or DC models, but we've seen mention of the need to monitor batteries with a unit like a Victron or Trimetric (I hate the "step gauge" type of installed monitors anyway, I call them "idiot lights"), so that's on the list, as is a possible solar panel array (our unit isn't prewired though).

But should the fridge really consume so much battery when running on propane? The problem seemed to be getting worse over our month-long trip, to the point we had to run the gennie morning and evening every day. And that really put a crimp in our hiking opportunities with most campgrounds limiting the generator usage times.

Thanks for any comments and tips from all you experienced folks.

The big 12 volt draws would be the interior lights (especially if not low wattage LED), vent fan and water pump or if left on all the time the inverter. Computers and device chargers can accumulate quite a load over the day if left plugged in all the time too. A light forgotten and left on in the basement storage area or closet can also add to the battery drain.

Yes be sure to use the energy saver mode if available to turn off any defroster coils in the refrigerator when dry camping. Also be sure if you have an inverter to lock the refrigerator into LP mode so it won't automatically switch to electric if its also powered by the inverter.

paof6 · 06-27-2021, 08:59 PM

We had the same batteries in our 2019 25B. At 60ah each they are very short lived for dry camping. Tested ok every time BTW. Finally had enough of that nonsense so after a year we swapped them out for a pair of true deep cycle batteries.

Elkman · 06-28-2021, 05:26 PM

For some reason the fridge is not making use of the propane as it should. There may be a problem with the solenoid that allows gas to flow from the tank or the flame is out. Troubleshoot the propane side of the fridge.

With my last camper if the angle exceeded 3 degrees in a particular orientation of the 3-way fridge the propane would shut off. I ended up using 2 inch thick blocks under the front tires when camped on an incline (that I checked with a digital level) to keep the fridge going.