My Dometic RV fridge is sucking my batteries dry and I can't determine why?!

Petenebraska said:

What kind of fridge??

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Norcold 4 door. 2 freezer compartments with ice maker and two refrigerator compartments. 1200 model.

Tecnodave said:

these look like replacement adsorption refrigeration units, not at all like what I am using.

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They have both. Absorption and compressor.

Johneb said:

If I was to do it again I would just replace it with a standard fridge to get the extra space. About 2 cubit feet of extra space. If you can find an inverter refrigerator it will lower your energy level even more.

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That's check number 3 in the compressor fridge category! I'm going to see what I can work out with my installer. Thanks for your insights!

The 7.6 cu-ft unit in the first 5th wheel had its cooling unit take a dump. Yummy! Ammonia! Yanked it and plugged the hole with foam board insulation because we have the double fridge in the other unit.

No way I'd consider a JC unit for one reason: I can get a fridge that fits in the hole that uses < 1kWh/day, costs < $600 AND has 10-11cu-ft of space vs. 7.6. You gain the volume occupied by the cooling unit when going residential. You don't get that from a JC "cooling unit."

If I may add. Get rid of the 12 volt converter as soon as you can.

Johneb said:

If I may add. Get rid of the 12 volt converter as soon as you can.

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Respectfully disagree. Left my converters and 12V systems completely intact for a secondary backup. So what if my 12V loads are only 75% efficient. They're a tiny fraction of my consumption.

sunshine_eggo said:

Respectfully disagree. Left my converters and 12V systems completely intact for a secondary backup. So what if my 12V loads are only 75% efficient. They're a tiny fraction of my consumption.

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But you have 3kW of AZ high desert PV and 23.3kWh of battery?! 75% of your system is still way more than 100% of mine. ...which I will never achieve...

Petenebraska said:

But you have 3kW of AZ high desert PV and 23.3kWh of battery?! 75% of your system is still way more than 100% of mine. ...which I will never achieve...

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I have a smidge of power paranoia. I have 2X inverters in parallel. If one goes out, I can use the other. I have my old 48V FLA bank on float in case my NMC bank takes a crap. If I lose both inverter and all batteries, I have a 24V, 2kW Inverter with 5kWh of AGM on float as well. If that goes out, I have a 4kW Predator generator. If that goes out, I have a 3kW Coleman generator. One of the 5th wheels also has a propane generator and a 420# propane tank attached.

Can't you see I need the on-board 12V as backup too?

Just wanted to jump in to say that I have a relatively inexpensive dc compressor fridge. 1.3 cu ft, Ausranvik(I think they're no longer around) but it runs great. It has not been turned off in years. Keeps milk good even in my 100 dg F plus yurt, or even in the front of my van on road trips. It recently had to run off an isolated 280 ah battery, and it ran for a week while the van was broke down in summer heat. I can't find more precise notes on power draw. I think it is roughly 60 watts while running, and runs for about ten minutes, depending on outside temps, of course. It never fails to keep temp, even if it may have to run longer.

I, too, am considering getting a second unit, because this one can achieve and maintain temps cold enough to keep ice cream, and I needs my ice cream and I could use another two or three cu ft:/ As to your twelve volt conversion issue, why not install a second solar panel system for the 12v circuits? 200 watts pv would really help out.

Petenebraska said:

Well, it says "compressor" https://jc-refrigeration.com/product-category/dometic-120v-hvac-cooling-unit/ but who knows until you have your hands on it. The website does say they'll mail it to you so you can install it yourself. After I cross reference my fridge model to the right compressor, I may think about that option...

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The Hvac 120V unit uses about 25% less power than the absorption unit uses on the electric setting. Power usage: 3 amps at 120V (360 watts).

Not really saving much

@Petenebraska please post a picture of the ac/dc distribution panel with the cover open so that we can see the breakers, fuses and corresponding maps.

time2roll said:

The Hvac 120V unit uses about 25% less power than the absorption unit uses on the electric setting. Power usage: 3 amps at 120V (360 watts).

Not really saving much

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Watts isn't Watt-hours.

It doesn't run 60-80% of the time like the heating element does:



This is with the interior and ambient running between 46 and 63°F. Maintain it at a comfortable temperature inside, OR if it's above 65°F outside and it's running 40-50 minutes out of 60.

I had a 43’ house boat and I had a 12 year old medium/small residential refrigerator/freezer onboard and two 8Ds and a GoPower puresine 3000 would power it for a week. But I had to disable the defrost cycle with a switch I wired up and once back on shore power I’d turn it back on. Defrost was a watt monster. Currently, in my house I have a two year old full size LG refrigerator with a “linear“ compressor, what ever that is. I just checked on my Emporia app and it draws 9.8 Ah a day on average(confirmed by another app by an overall correlation). When it’s running it draws 48 watts with spikes about every 11 hours to 140 watts that’s probably a defrost cycle. Man they got efficient. Yeah I think I’d be dumping the Dometic.

Yurtdweller said:

Just wanted to jump in to say that I have a relatively inexpensive dc compressor fridge. 1.3 cu ft, Ausranvik(I think they're no longer around) but it runs great. It has not been turned off in years. Keeps milk good even in my 100 dg F plus yurt, or even in the front of my van on road trips. It recently had to run off an isolated 280 ah battery, and it ran for a week while the van was broke down in summer heat. I can't find more precise notes on power draw. I think it is roughly 60 watts while running, and runs for about ten minutes, depending on outside temps, of course. It never fails to keep temp, even if it may have to run longer.

I, too, am considering getting a second unit, because this one can achieve and maintain temps cold enough to keep ice cream, and I needs my ice cream and I could use another two or three cu ft:/ As to your twelve volt conversion issue, why not install a second solar panel system for the 12v circuits? 200 watts pv would really help out.

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Now that's an idea I haven't thought of before. I have got the real estate upstairs for a couple more panels. The camper even has a port for a panel to charge the battery. I suppose I could pick up a panel at Harbor Freight. I'll look into that option as well. Thanks!

Skypower said:

I had a 43’ house boat and I had a 12 year old medium/small residential refrigerator/freezer onboard and two 8Ds and a GoPower puresine 3000 would power it for a week if. But I had to disable the defrost cycle with a switch I wired up and once back on shore power I’d turn it back on. Defrost was a watt monster. Currently, in my house I have a two year old full size LG refrigerator with a “linear“ compressor, what ever that is. I just checked on my Emporia app and it draws 9.8 Ah a day on average(confirmed by another app by an overall correlation). When it’s running it draws 48 watts with spikes about every 11 hours to 140 watts that’s probably a defrost cycle. Man they got efficient. Yeah I think I’d be dumping the Dometic.

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I just read your post to my wife and commented that before we moved into the camper, we too had an LG fridge with a linear compressor. We bought it used and had it until we moved out. She said "that makes sense because our electric bill went down after we got the new fridge." Way to go LG. I wonder if I can find a smaller fridge with a linear compressor. Thanks for the reminder!

John Frum said:

@Petenebraska please post a picture of the ac/dc distribution panel with the cover open so that we can see the breakers, fuses and corresponding maps.

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For what it's worth:

Petenebraska said:

For what it's worth:

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Its a 50 amp rv with 2 air conditioners and 2 microwaves.
The panel has 2 master breakers one for each leg of the 120/240VAC supply.

I'll be the first to say that I'm interested to know the details of the integration with the legacy system.
The 3rd picture in your original post shows shows an inverter/charger.
Is that the new EG4 or some legacy inverter/charger?

My two cents; I have an absorption refrigerator in my trailer. When I'm plugged into shore power, I'm using the 120VAC heater element and when I unplug it switches to propane. I believe in your case, solar is feeding the 48V system, the inverter is making 120VAC and your trailed is "plugged" into it. Your 12VDC is running like it did before the conversion (your old converter charges the battery and runs the lights). If you can live with the converter efficiency, you won't need the DC2DC. You need 12VDC for lights, fans, furnace. I'd turn off the refrigerator breaker and run it off propane. What is heating your water, I'd use propane for that as well.

Just noticed the second microwave and the second air conditioning unit are on the same breaker.
Thats a bit unusual.

Most Dometic adsorbtion refrigerators do need 12 volts dc to power the gas solenoid and logic circuits.
The logic board is powered by 12 volts dc no matter what the source of cooling. Even if you are powering from AC to run the heater elements, the logic board and gas solenoid are powered by the 12 volt circuits and the 12 volts dc must be there for this.

Some Dometic and others have dual heater elements 120 volts AC AND 12 volts DC. This is selected by thr function switch on top front of referigerator.

Some models also tap into the ON position (engine run) of the vehicle to automatically run the frig in 12 volts DC while engine running and then switch back to propane after a 10 minute delay ( SAFETY DELAY) In case you are fueling the vehicle. This is required for safety and was implemented after several instances of fuel station fires ignited by propane referigerator ignition.

The 3 wire connector for DC are +12 v. dc , -12 v. dc , ignition run (sometimes black, red, orange)

I have used this function to switch between solar power and propane with my own logic board which detects solar battery state

MUCH MORE.....detail can be found in the Dometic Dealers Diagnostic manual which is RARE..... I have that manual in PDF format and will happily post it or email it to you

Complete theory of operation, diagnostics etc. It is still posted at Dometic.com but it’s deep down there in the manuals for older models

I have long since given up on adsorption referigeration since the event of dc driven permanent magnet motor drive referigerator conpressors. (DANFOSS)

little tidbit....the wheel motors in electric bicycles is the same exact technology as the Danfoss compressors.

Sorta like a three phase motor but with the coils energized by DC pulses from the logic boards.

My family’s homestead was served by Servel refrigeration so I have just a tidbit of experience with adsorption refrigeration ......yep born in the backwoods of Territorial Alaska....just south of “the great one” (Denali Mount) an off gridder from birth

So far it seems this RV has a 120/240VAC all in one, a legacy 120VAC inverter charger(which is currently in inverter mode) and a legacy ac2dc converter.
The inverter charger is also set to a charge profile intended for LFP batteries.
In opinion the float voltage is way too high for LFP batteries though.
OP I urge you to revisit the integration.

The absorption process is driven by heat.
The efficiency of electric heat is only about one third at best as the same electric running a heat pump.
Your refrigerator is probably doing as well as it is supposed to using electric.
Absorption refrigertors should only be used when there is no source of electricity.
Now that you have a robust source of electric, consider upgrading yout frigde.

OP what type of lead acid batteries do you have?
I mean flooded, gel, AGM or something else?

John Frum said:

Its a 50 amp rv with 2 air conditioners and 2 microwaves.
The panel has 2 master breakers one for each leg of the 120/240VAC supply.

I'll be the first to say that I'm interested to know the details of the integration with the legacy system.
The 3rd picture in your original post shows shows an inverter/charger.
Is that the new EG4 or some legacy inverter/charger?

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Very close. Modifications were made:
It's a 50amp rated service but one leg of the connection has been disconnected so it can only bring 120v into the EG4 (not a 240v model). The 50amp breaker is a combined breaker. there are two separate breakers connected by a tab.

The rig has 2 A/C units that operate independently on separate thermostats. There is only one microwave. Disregard the "microwave" label. It's the bedroom a/c.

The 3rd picture is the front face of the EG4, just for reference. It's a tight fit in the front compartment so I couldn't get a pic of the whole unit. The legacy/original inverter/charger is, as one respondent suggested, the cheapest/easiest thing that the manufacturer could install at the time of manufacture. I don't think any wiring was changed or added to attach it to the system. The new EG4 was just wired to the breaker panel "around" the original 12v inverter/charger.

McKravitts said:

The absorption process is driven by heat.
The efficiency of electric heat is only about one third at best as the same electric running a heat pump.
Your refrigerator is probably doing as well as it is supposed to using electric.
Absorption refrigertors should only be used when there is no source of electricity.
Now that you have a robust source of electric, consider upgrading yout frigde.

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And that's the direction I'm leaning. Seems the most logical solution for the long term since we live in here full time. Thanks!