RM36E 3way refrigerator

I have a Rm36E 3way fridge.

Looking at the tag, which is hard to read now, it looks like it's 1.1 amps at 120vAC or 3 amps at 12vDC. Am I reading that correctly?

If so that would be 121 watts on AC or 36 watts on DC, right?

I tried running it on AC through my inverter and it sucked my batteries dry overnight.

Obviously it will use more than the rated on AC as there are inverter losses to consider.

I have 400Ahr of batteries in my main bank so I assumed it would be enough to run it on AC through the inverter, but am obviously wrong, so what am I missing.

Do not suggest I buy a different refrigerator, this is the one I have that I'm working with so it's irrelevant how much better a different one might be

If the 3rd way is propane, that's an absorption fridge, and it uses 5-6X the energy of an equivalent compressor fridge. They burn about 300-325W of AC or DC power.

I had a 7.6cuft dometic that consumed about 5kWh/day - that's the equivalent of 420Ah @ 12V in a 24 hour period, and at least 1000W of solar dedicated to replenishing the energy used in 24 hours.

Run it on propane.


Lists the burner demand of a RM36C @ 1000BTU/h. That's right around 300W of power.

While you may not be receptive, I replaced a 12cu-ft NeverCold that used 9-11kWh/day with a $400 Magic chef 10.1 cu-ft that uses less than 1kWh/day - a 10X reduction in consumption with a 20% reduction in volume. HOWEVER, the 10.1 cu-ft is notably deeper due to the lack of the absorption cooling unit, and the space is MUCH more usable.

If you won't run it on propane, you need to invest in a LOT more capacity. At that point a different fridge becomes WAY more practical.

EDIT: I did find a manual that lists your unit at only 135W. Since that's well below what the burner is capable of, that's likely going to run continuously rather than cycle on and off. That's 3.2kWh/day.

Its not a matter of not being receptive, it's a matter of not having the money to buy a different one at the moment.

Any idea how long a 20lb propane tank would last running just this fridge?

We've lived 3 years without one at all and can keep doing it. It would just be nice to be able to have a really cold beer once in a while lol

TomC420 said:

Its not a matter of not being receptive, it's a matter of not having the money to buy a different one at the moment.

Any idea how long a 20lb propane tank would last running just this fridge?

We've lived 3 years without one at all and can keep doing it. It would just be nice to be able to have a really cold beer once in a while lol

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Our 30# tank ran our 7.6 cu-ft unit for about 3 weeks. It depends heavily on ambient and usage.

Using 1000BTU/h:

1lb propane about 21K BTU, so 21 hours of continuous running per lb.

420 hours continuous for 20 lb.

Assume a 60% duty cycle (about what I saw), 420/.6 = 700 hours

700/24 = 29 days.

I would expect that's a minimum unless you're really careless about usage.

You could probably stretch that by powering it via AC during peak solar. When we were offsite, that's what I would do... run it on AC for about 8 hours/day where I could "pay for it" with active solar and then switch to propane at night. I had a programmable AC plug that could turn on and off on a schedule. "AUTO" mode would select AC if available, then default to propane when AC was lost. Not sure if yours has that feature.

Might be worth seeing if you can pickup a used mini fridge in your area. Found several in my area at $25-60 on craigslist, but I understand Phoenix is likely much larger than your area.

TomC420 said:

We've lived 3 years without one at all and can keep doing it. It would just be nice to be able to have a really cold beer once in a while lol

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Block ice and an average cooler out of direct sunlight is easily good for days.

OzSolar said:

Block ice and an average cooler out of direct sunlight is easily good for days.

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I've never checked the math or figured out why, but I found that letting the water drain as the ice melts to retain the ice for longer. Maybe it has to to with reducing the cooled mass, or I'm full of crap, and it was a weird fluke.

sunshine_eggo said:

I've never checked the math or figured out why, but I found that letting the water drain as the ice melts to retain the ice for longer. Maybe it has to to with reducing the cooled mass, or I'm full of crap, and it was a weird fluke.

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I think I remember something like that from physics and scuba diving.
If I remember correctly (which is highly unlikely), water being much denser than air has a much higher thermal conductivity than air. I think from my diving days it is like 25 times more. So with the faster heat transfer, you get faster melting in water than air with nature's never ending quest twoard equilibrium.