Originally Posted by JRTJH
Methinks you're leaving out the propane side of absorption refrigeration. You are correct, when running a "gas/electric refrigerator" on "electric" it uses 325 watts for electric operation (on a 2 way refrigerator, that's ALWAYS 120 VAC because it uses shore power at about 2.7 Amps... If you use a inverter to power the refrigerator on electric, then the refrigerator would use 325 [email protected]
VDC, but who would do that when propane uses less than 30 watts of battery power ?????
So, comparing apples to apples (rather than apples to oranges) a typical gas/electric 2 way absorption refrigerator, when dry camping and running on propane only uses about 2 amps of battery power and nearly all of that is consumed by the "door seal heater" not by the actual electronics/refrigeration components.
When compared to a compressor refrigerator of similar size, the absorption refrigeration system "substitutes propane for electricity" and is SIGNIFICANTLY more battery saving than any compressor refrigerator of similar size.
For me, energy is energy - apples to apples.
This was in the context of the OP indicating:
Our goal is to conserve energy. We’re ok with losing the propane connection as we’ve got 1000ah of LiFePO4 and lots of solar.
"battery saving" was not the goal.
On propane, the fridge still uses a large amount of energy. A 30# bottle of propane has about 160kWh of usable energy. Assuming ~90% efficiency, that's 144kWh. At about 5kWh/day of consumption, that's about 29 days of operation. In my experience, it's closer to 3 weeks on a single bottle.
Ultimately, it doesn't matter where the heat energy comes from. It's about 5kWh/day (mild ambient conditions). If your goal is to conserve electrical energy and not use propane, then a compressor fridge is the only choice.
OP has 1,000Ah @ 12.8V, or 12800Wh of energy. That's nearly 13 days of operation of a ~10cu-ft compressor fridge. Knock a day off for inverter inefficiencies. 300W of good
solar can more than offset that daily. I think, "lots of solar," is probably more than 300W.
I'm not just guessing. I'm been powering two RVs for 2+ years with off-grid "shore power" consisting of 10kW of 120/240VAC split phase power, 3000W of solar and 23.3kWh of DIY Lithium batteries from Plug-in Hybrids in a 40' shipping container. The 50A "shore" pedestal is split to provide one leg to each trailer. I've powered both fridges purely from AC, and it's quite costly.
I've attached a picture of the "ranch" and a chart showing the AC cycling on and off. 3/5/2023 - 25°F low and 41°F high temp for that day. On that day, in those cold ambient conditions (fridge hadn't been opened for 2+ months), it used 3.8kWh.
FWIW, I can confirm with 100% certainty that the propane follows an almost identical cycling pattern because I could see the ~2W bump when the propane valve would open.
ANYWAY, I find myself in this same predicament now that the fridges in both trailers have failed, so that's why I'm poking around the issue. I'm undecided on which way to go. I vastly prefer the efficiency of the compressor fridge, but I don't plan to have these forever, and they would definitely need battery and PV upgrades for boondocking for the next owner. Plus, the cost of new cooling units isn't as high as I thought it was - about half that of a new compressor fridge... I'm torn. PLUS, I have 2X the solar and 2X the battery waiting in the wings as this system will power an eventual permanent dwelling.
Stupid first world problems...
Originally Posted by chuckster57
If memory serves me right the Norcold1228 has fans mounted INSIDE the fridge for more efficient cooling and I know for a fact that if you have a single GP 24 battery it will kill it overnight. BTDT
As a test we left a new Fifthwheel plugged in all day and the fridge on AC to cool, Left at 5PM with the fridge on LP and unplugged from shore power. It was no longer operating at 8AM the next day. Temp was set on 4 IIRC.
Yeah. A GP 24 battery has somewhere around 80Ah, so that's only good for about 2-3 hours of full power operation. If it's already at temp and maintaining, then you might get 3-6 hours. Back when I was a n00b, I obliterated my 2X 12V 200Ah BlueRivers in series overnight.
I don't follow the point in your second paragraph.