Propane refridge

[barnyard]

With the popularity of solar power is it still desirable to have a refridgerator that has propane feature? have to replace my refridge and wondering if 12v/110v is sufficient

[Shane826]

If you’re going just electric you don’t need an AC/DC fridge. Just get a 12V compressor style fridge and never look back.

[Bill]

Shane is exactly right. If you have plug-in AC power, then the TM's converter will supply all the 12VDC power you need. And if you are boondocking on solar power, your solar system will provide the 12VDC power you need for your refrig. You never need AC power for your refrig.

Again as Shane said, get a compressor-style refrig. I will add that you should NOT get side-tracked onto a 12-volt thermo-electric refrig, lured by its very low price. They are absolutely unsuitable for your primary refrigerator.

If you like, you can Search the Forum for "thermo-electric" to find the list of reasons.

Bill

[rickst29]

Maost of the the "12 volt DC" refrigerators contain built-in converters. My own Dometic model switches to use 120-VAC automatically, when it detects that 120V power is present.

These 12 Volt DC capable refrigerators tend to be expensive, in comparison to dormitory-sized household units (120-VAC only). The first issue with a dormitory-style fridge/freezer is the high current (power requirement) needed to start the compressor. That's typically about seven times more than the labeled average running watts. A '400 watt' dormitory fridge therefore needs a converter capable of about 2,800 watts, consuming all of the "savings" on the fridge -- unless you also need that converter for other reasons. If you buy a smaller converter to drive such a refrigerator, you WILL burn out that converter.

Compressor-based refrigerators of both (12 volt DC specialty units AND household units) are both more efficient than the heater-based 'absorbtion' refrigerators widely used in RVs. When using battery, than need only about 1/4 as much power (in watt hours).

The second issue with those 'dormitory-style' is the wide range of outdoor temperatures which the TM fridge needs to handle. Most of them are designed for "indoor use only". So I recommend that you invest much more to buy a 12-VDC refrigerator instead, they're built using a special low voltage DC compressor. That Danfoss compressor (and its clones) also have extremely low "compressor start surge requirements", with no need for bigger wire size or battery capabilities.

Most of the fancy '12V compressor' refrigerators can also maintain safe and cold interior temperatures much better than the absorption refrigerators. (My original TM fridge couldn't stay cold when outdoor temps exceeded about 95 degrees, while my replacement "12V compressor unit" is widely used by tour operators in excursions to Uhru ('Ayer's Rock) in Australia - temps above 120 degrees are common). I've never had even the slightest problem with mine, although my highest outdoor temps have never exceed about 105.

[Shane826]

Rick- If I recall you have a Dometic CR1110 AC/DC fridge? That one is capable of switching on its own. The new 12V fridges are just 12VDC and rely on the camper’s converter to switch AC to DC when on shore power. You can get a 3.3cf 12V fridge in the $500 range.

Or, do what I’m working on… 4.5cf 120VAC fridge with a transfer switch and converter. Costs a little bit more (I’m in the $700 range total) but provides a bit more flexibility with the household outlets now able to be powered by the battery.

[rickst29]

Originally Posted by Shane826

Rick- If I recall you have a Dometic CR1110 AC/DC fridge? That one is capable of switching on its own. The new 12V fridges are just 12VDC and rely on the camper’s converter to switch AC to DC when on shore power. You can get a 3.3cf 12V fridge in the $500 range.

Or, do what I’m working on… 4.5cf 120VAC fridge with a transfer switch and converter. Costs a little bit more (I’m in the $700 range total) but provides a bit more flexibility with the household outlets now able to be powered by the battery.

Yes, I have that older and much more expensive Dometic. (I was probably the first TM Onwer to make that switch. At that time, the fridge was only listed by Dometic as "boating" product for yachts, it was not listed as a RV product at all.) Thanks for the info regarding the newer and cheaper 12V-only units.

Will your Converter be capable of 3000 watt peaks? You should not install a Converter with a lower rating.

Also make sure that your Converter does not 'bond' the AC-Neutral (White) and Safety Ground (Green) outputs for "shared use, higher efficiency" before reaching the Inverter's output electronics. That horrible "feature" is incompatible with GFCI circuits, and also subjects the batteries to a bit of 60-cycle noise on the DC ground plane.

[Bill]

Just adding an FYI. We bought a 44-qt Engel MT44 compressor unit in about 2002. Scary expensive, but we were about to do extended TM traveling through the desert southwest, and nothing similar was available at the time. It had a single compartment, any temp setting from 0* to about 50*. Auto-select 12VDC / 115VAC.

Wonderful unit, maintained 0* when the TM's interior temp hit 110*. When we got home, we ran it 24/7 as an aux frig in the garage for years. Finally began to malfunction in about 2015. Engel Customer Service phone call diagnosed a power supply problem, they sent out a new unit, I installed it - up and running to this day.

Engel's Sawafuji "swing motor" compressor, like the now-famous Danfoss compressor, is very efficient. Ours draws 2.6 amps @ 12VDC when running, and at 95* ambient, it holds 5* inside temp with 47% run time, so average current is about 1.2 amps. I tried to measure a turn-on surge, and it didn't have one. For 5* freezer temp at 95* ambient, I think that is outstanding.

If I sound like I am shilling for the Engel, it is because I love ours. Today, both the Danfoss and Sawafuji compressors have entered the realm of legend (look them up), and today you can choose from a number of refrig/freezers that use one or the other. Either will be an excellent choice. If you want a rugged reliable unit for extended use - as opposed to the occasional picnic - I would recommend spending some extra bucks to get either one.

Bill

[kjfatl]

I picked a compressor frig that runs at 110V or 12V. It uses 110V if available and falls back to 12V when necessary. I was concerned that a continual load on the 12V inverter would reduce the life of the inverter unnecessarily. In the long-term I will probably get a larger solar panel for the top of the camper that can keep the frig going when AC power is disconnected for an extended period of time.

[Wavery]

My 120V 4.5cu ft dorm fridge used about 500W for about 2 seconds at start up. It ran 90W when the fridge was cooling down and 35W after the fridge was cold. I ran it off of my 2000W inverter with no issue at all and it would probably have run on a 500W inverter just fine.

At the time that I installed my fridge the 12V fridges were quite expensive. Although I would probably opt for the 120V dorm fridge anyway. Power consumption was never an issue.

My thought with preferring the 120V dorm fridge is, if the fridge goes out on a long trip, getting a replacement in a timely manner, in God knows where, would be next to impossible. That would leave me with no fridge for the duration of the trip or stuck is some town, waiting for a new fridge to be delivered (somewhere?). 120V dorm fridges can be found in most any town, anywhere in the US and I would be out another $200 as apposed to $1200 (after I got home).

As some people know, it is quite a rough ride inside of the TM when going down the highway. Things often fall apart or screws come out. The compressors inside all of the compressor fridges are mounted on rubber mounts and the refrigerant lines are solid copper lines. Those lines are subject to a lot of shock loading and the possibility of a line cracking is high (in my opinion) over time and miles on the road.

[Shane826]

^ Yeah what he said. ^