The Refrigerator Dilemma(s)

[Brianna]

My 2000 Alpine has the groovy 1292 New Dimension refrigerator.

Although it is working fine with no signs of any wear or leaks in the burner and tubing, I have decided to have JC Refrigeration swap out the 3-way system with a compressor system.

There are other forum threads to discuss the safety /danger aspect and pro/con of the good-old tried-and-true absorption frig, but here I wanted to specifically discuss the pros and cons of a little DC compressor vs a little AC compressor.

Given the math, comparing AC Amps to DC Amps, which would make the most sense in my case?

Typical 450 usable Ahr battery bank, 2000W inverter, 800W solar, boondocking for one 24 hr period.

[Old Scout]

….seems like "modernizing" an old absorption fridge is a bit like "putting lip-stick on a pig." Most modern residential fridges use small compressors [often DC with internal converter] and run almost continuously but use little energy....counter-top depth and over all dimensions tend to limit model/brand selection and drive up price a bit.....with your bat capacity and solar set-up and modest dry-camping goals...it sounds like you are in good shape to go with a residential fridge--IMHO.....

[RVPioneer]

Can you provide us with the amp ratings of the current and proposed refrigeration systems?

There are still many variables. Ambient temperatures, how often each system actually runs, contents of the refrigerator, etc. Additionally, there will be variables with your solar output and energy usage from other appliances.

I’m very interested in this as we’re considering one of the JC options as well.

[vsheetz]

I'd suggest to go with a counter depth residential refrigerator. More commonly done now. Likely more efficient.

Imho. Ymmv.

[paul65k]

I just made the change to compressor-based a few months ago and agonized for quite some time before coming to a final decision.

I looked very closely at the JC system and talked to them on the phone a couple of times. The System of choice for me is the 12V compressor-based considering it will be running on 12V the majority of the time and there is no energy cost/loss in converting from 12V to 120. Personally I am not really enamored with the off-brand 12V compressor they use, I asked them if they would consider an upcharge for a Danfoss compressor and they sounded interested but went radio silent.

In the end I went with a residential refer which was actually cheaper than the JC conversion, it is very low energy use wise but the biggest thing was to get a refer that is 50% larger and way nicer IMO.

With our battery bank and solar, we have no issues at all and will not look back!

[AKOne]

Almost went the JC route because of the "fit in the space issue" -- height, width, depth and door swing. Furnace is located underneath. In the end only one residential frig would fit -- Fisher Paykel. Still had to rebuild the platform to lower it. Do have to say, as a DYI, this was to most labor intensive projects I done so far.

Pictures can be found here: https://1drv.ms/u/s!ArBcunudL8RpgotX...3hpvg?e=4Tkxmv

[Brianna]

RVPioneer,
The 12v system from JC (according to the mortons) uses 5.5 DC Amps while the 120v system uses .8 AC Amps.
Unfortunately, I am not knowledgeable enough to be able to extrapolate that data (sounds like a high school exam question).

Obviously, if you're plugged in somewhere, it doesn't matter, but if you're running on batteries, which would be more efficient?

PS that fisher paykel frig is gorgeous!!!!!

[twinboat]

A 120 volt unit drawing .8 amps converts to 8 amps at 12 volts DC. Its 10 times as much.
Then you need to add in the 10% to 15% losses thru the inverter.

One other consideration is how long and how often the compressor runs. The better insulated the box is, the less power it uses to keep it cold.

[paul65k]

My new residential GE refrigerator is using 6.2A (When running). This makes sense as the insulation would be/is better.

I have not heard of anyone that thinks 12CF is better than 18 CF in the same space with lower energy use....... get the residential unit

[RVPioneer]

Twinboat did the conversion, now the estimating begins. How many hours per day will the compressor run? If we say 6 hours, the DC unit will use 33ah of capacity (5.5x6), the AC unit will use 54ah, (9x6, 9 due to inverter loss). All things being equal the DC unit will be more efficient. Neither will deplete your battery capacity after 6 hours of cumulative run time.

The only way to accurately compare energy consumption between the 2 units, and your current absorption refrigerator, and a residential refrigerator would be to have all 4 units installed in a coach, each with identical contents, same ambient temperature, same amount of door opening, etc, and individuality measure the energy usage of each unit.

Refrigerators use less energy when they are fully loaded with cold food. If you opt for a larger residential refrigerator, as some have suggested, and only fill one or 2 shelves with food, it will be working to cool a large volume of air. We have the slightly larger 14 cu/ft model and are always amazed at the amount of food it holds.

Whatever option you choose, it will be to your benefit to bring the refrigerator down to a cold temperature the day before, while plugged in, if possible.

[AKOne]

Originally Posted by Old Scout

….seems like "modernizing" an old absorption fridge is a bit like "putting lip-stick on a pig

That was the conclusion I came to, maybe not quite in those terms. If I modernized my pig with make-up, I would still have old leaky door seals, manual defrosting, broken hard to find interior parts and limited space. The number one reason for going with residential was safety.

My two cents on the energy consumption. Without getting all techy:
-- The residential frig while on the road, energy use is a non-issue - engine running charging batteries while inverter is doing its job keeping the frig going.
-- Shore power, no brainer.
-- Dry camping, inverter running, good for about 10 to 12 hours with 4 Trojan T105s 6 volt batteries - TV watching that night, some 110 lights on, maybe a few minutes with a hair dryer, water pump now and then, furnace on all night and frig on all night. In the morning, batteries are showing 12 or more volts.

I tried figuring all the power consumption angles - numbers, variables Then decided to go for it and when dry camping I will just see what my batteries endurance will be. Certainly not scientific. Only took a couple of nights dry camping to know just how long my batteries will last until needing a charge.

So I saved the money on the lip-stick on bought a new residential frig.

[Brianna]

Thanks everyone.
Clearly NOT just a math problem.
It makes sense that, even though it may use more power, the Ac residential frig would probably not run as often for the reasons you laid out.
Hmmmm.

Akone, what residential frig brand did you end up buying? Did it pop right in or did you have to revise the side trim and lower the compartment floor?

[Ljwt330]

Originally Posted by Brianna

Thanks everyone.
Clearly NOT just a math problem.
It makes sense that, even though it may use more power, the Ac residential frig would probably not run as often for the reasons you laid out.
Hmmmm.

Akone, what residential frig brand did you end up buying? Did it pop right in or did you have to revise the side trim and lower the compartment floor?

Take a look at this thread, https://www.irv2.com/forums/f104/fri...on-469365.html and read the posts by paul65K. Some excellent pictures and information about refrigerator install and the necessary cabinet changes. He went with a GE brand though a Samsung model will also fit.


From what I've researched, some cabinet mods will have to be made regardless of the Alpine you have, and those cabinet sizes will limit the refrigerator choices due to height and depth. None of those changes, however, are difficult for the average handyperson.

[RVPioneer]

Since you may have been talked out of your original plan, yet another option would be to install a Fridge Defend and a fire suppression system and just keep your properly operating refrigerator for a few more years.

At what cost are you willing to reduce battery consumption by ~20Ah over a 24 hour period on a battery bank with a capacity of 450Ah and 800w of solar in the roof? It almost sounds like a solution looking for a problem.