12 V DC refer and battery life

[ErnieSeabee]

I have a 2022 forester 2401 MBS with a 12 V Magic Chef refer. In 70+ degree weather ( ambient inside cabin) the refrigerator on setting #2 runs quite a bit and can kill a pair of house batteries in 4-5 hours. This normal? Refer runs for upwards of 30 minutes to make temp shuts off for a while then reruns another 30 minutes?

[Ballistic]

A couple of things, 1) if the batteries aren’t at a minimum a dual purpose battery, then I would expect the runtime you described. 2) if the exterior wall residing behind the fridge is facing the sun/in direct sunlight, then what you’re describing is normal for cycle runtime.

In my everchill fridge at an ambient temperature of 65-75 setting 1 is adequate. With higher ambient temperatures setting 2 is required and cycle runtimes do increase significantly.

I’m working on a project now to vent the air in the cabinet behind the fridge as I’ve experienced thermal runaway and the fridge internal temperatures never recovers due to lack of venting.

[ErnieSeabee]

Ballistic thanks so much . Great thoughts on the wall behind the refer. Crank out the awing and cut down the sun load

[GolfingDave]

Magic Chef 12V ref, dual batteries(75AH deep cycle), temps down below 40 and less easily at night boondocking this winter.

Sun sets early in the evenings and got down to 50% battery life at sun up.
Running fridge and propane heat with 12V blower. I would bet my heater blower is drawing more current overall than the fridge.

Standard residential refrigerators run 50-60 percent of the time. Refrigerators are more efficient if kept full. Keep jugs of ice and water in them if not full of food.

I don't think your batteries should be running down after just a few hours. Believe what you are seeing there is more of a battery problem or another drain of power.

[tomkatb]

Maybe is the answer.

How long your car battery lasts is highly dependent on usage especially of the fridge.

Senior users pre-chill the rv carefully on shore power. Try not to put warm stuff in the fridge. They fill empty spaces with jugs of ice later to be drinking water. If your fridge is not prechilled correctly, I would expect the battery to give out pretty quick.

These fridges are often installed incorrectly. Find the installation manual. These compressor fridges are sort of designed to be free standing. Wedging between cabinets is often not ok.

Their heat from the heat pump comes out the front of the fridge. So, think about vents. Gas electric fridges love cooling fans between the fridge and wall. I doubt compressor fridges would change much. Perhaps a fan in the floor pushing air into the room?

The math sort of indicates you do not have enough battery to last more than a day. I would think you will use 100 ah per day. Your car/boat batteries have about 75 ah available. Weather dependent. So, you need batteries.

If you are going to sleep disconnected much then you need more power. A lot maybe.

Study up. Make a plan. A battery monitor is a good plan if you plan much boondocking.

Our rv came with 4 gc2 batteries. About 220 available ah. Not enough for three nights. We have 405 ah of lithium batteries now. $2000. Honda generator $1000. We were careful about shore power the first years. Then, the DW, discovered Harvest Hosts. Makes her happy to sleep for free.

Not a fan of solar. Not so valuable in the Midwest.

[jimmoore13]

[RANT]
12 volt compressor fridges are a VERY poor choice for boondocking. The "old fashioned" 2-way fridge that runs on 120 volts or propane is the right choice for "dry camping."
[END OF RANT]

By all means, investigate the power consumption of your fridge. It sounds as if it's abnormally high.
https://thecampingadvisor.com/magic-...-refrigerator/
Do the math, and you'll see that you should expect, in round numbers, about 3 amps load for maintaining, and let's assume a 50% duty cycle. That equals 3 x 12 = 36 amp hours for battery consumption per day.

In your case, you have what I presume are two group 24 marine batteries rated at a generous 75 AH capacity. You get to use half of the total 150 AH (75 AH)...which means that you SHOULD be able to last 24+ hours with the fridge, furnace, water pump, spark ignition for the water heater, lights, awnining in and out, and, if you have one...slide operation.

That's the picture. On a good day, you get one day...but not 5 or 6 hours. Figure out why your fridge is so power hungry...or your batteries are shot.

Next? You need, in order of importance:

• Generator
• More battery...LOTS more
• Solar...and lots of it.

I have a 2 way fridge. I have two 6 volt golf cart batteries (GC-2s) in series with a total USABLE capacity of about 115 AH, and I have 400 watts of solar on the roof. We don't worry about 12 volt power. I also have a generator, but I only use it for 120 volt loads...like the microwave and espresso machine. After all, we aren't savages.

My points are:

• Check your batteries. Maybe they're toast (see P.S. below)
• Investigate why your particular fridge is such a power hog. All 12 volt compressor fridges use lots of power, but yours is off the charts.
• You need LOTS more 12 volt storage (battery) and generation (solar and generator) to make this thing work when boondocking.

12 volt compressor fridges are horrible choices for boondocking. They are wonderful fridges for RV parks with hookups. Manufacturers are moving to 12 volt compressor fridges, because they are cheaper to install, have 40% more capacity for their given physical size, and anyone can use one....unlike propane fridges which require a modicum of skills.

Re-read the rant.
You own a 12 volt fridge, so make the necessary adjustments so you can enjoy your RV in the boonies.

P.S. If you have repeatedly drained your batteries "dead", they are ruined. You can only use half the capacity of a FCLA (flooded cell lead acid) battery. If you drain it dead...especially several times...it's ruined and won't hold a charge.

So, before you go bananas investigating the fridge, think long and hard about the possibility of past battery abuse. Maybe your fridge is fine, but the batteries have been drained dead over and over, so they won't hold much charge...thus the 5 to 6 hours of life with the fridge.

This also presumes that the electrolyte levels have been maintained, AND that one of the batteries hasn't just failed...as things sometimes do. Take your batteries to an auto parts store and have them load tested...and you'll know.

P.P.S. Batteries good and fridge performing as it should? Now you're stuck solving a bigger problem. What's eating your battery alive that you don't know is doing it? A mystery power draw can't be ruled out if none of these suggestions pan out.