Pros and Cons of 3-Way Absorption vs 12V Compressor RV Refrigerators

There isn’t a one-size-fits-all RV refrigerator. And it makes me so mad.

You have five options for RV refrigerators:

  1. 3-way absorption refrigerator
  2. 2-way absorption refrigerator
  3. AC/DC compressor refrigerator
  4. DC-only compressor refrigerator
  5. AC-only compressor refrigerator

I’ll run through your options. And I’ll grade each option on four criteria:

  1. Cooling Performance
  2. Off-Grid Capability
  3. Storage Space
  4. Cost
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Table of Contents

Introduction to the RV Absorption Refrigerator

The most common refrigerator in an RV is an absorption refrigerator. I wrote a full guide to the absorption refrigerator here.

Absorption refrigerators are expensive, hard to fix, and prone to operating problems at high altitudes – but they can run off nothing but propane (and a little bit of 12V electricity for the control board). That’s their saving grace. They’re rather crude, but they work when nothing else does.

Absorption refrigerators come in two flavors: 3-way and 2-way.

  • 3-way absorption refrigerators can operate on propane, 12VDC, or 120VAC power.
  • 2-way absorption refrigerators can operate on propane or 120VAC power.

Absorption refrigerators can run off gas or electricity before they require heat. Yes, I know it sounds backward because it’s a fridge, but the appliance uses a heating element to move refrigerant.

P.S. The term “2-way fridge” is sometimes used to refer to an AC/DC fridge, and sometimes used to refer to an LPG/120VAC absorption refrigerator. The correct use is the second.

Introduction to the RV Compressor Refrigerator

Compressor refrigerators are what you have in your house. They work the way you’d expect. Turn them on, and 15 minutes later, it’s cold inside!

Compressor refrigerators come in three flavors: AC, DC, and AC/DC.

  • AC refrigerators can only operate on 120VAC power. These are also called “residential” refrigerators.
  • AC/DC refrigerators can operate on both 120VAC and 12VAC power. These are also called “marine” refrigerators.
  • DC refrigerators can only operate on 12V power. These are made specifically for vans, trucks and RVs.

Compressor refrigerators come with a lot of benefits. No more waiting 8 hours for an absorption refrigerator to cool down. No more desperately stuffing the fridge with ice packs. No more venting noxious gases to the outside air.

Isn’t it wonderful? They walk and talk just like Ol’ Reliable Fridge back home!

… that is, until the power shuts off. Because true to their name, compressor RV refrigerators can’t run off propane. They need the juice. No electricity = no refrigeration.

***

So let me break down some options for you. Because you won’t find a fridge that can do it all.

Option 1: Deal With the Quirks of an Absorption Fridge

  • Cooling Performance: Poor
  • Off-Grid Capability: Excellent
  • Storage Space: Fair
  • Cost: Medium/High

Your first option is the simplest: Stick with the same fridge your Dad and Granddad used in their campers: An absorption fridge.

You can find 3-way absorption fridges in every size of RV, from the smallest teardrop to the largest Class A. They are the default choice for almost all towables.

Absorption refrigerators rely on heat to move the refrigerant. So each fridge has both a propane burner and an electrical heating element, which can be powered by 120V AC power (2-way) and 12V DC power (3-way).

But let me go ahead and pop your bubble. You don’t want to run a 3-way fridge off 12V battery power for very long.

Don’t take my word for it. Just listen to Dometic talking about their DM2672 refrigerator:

“Switch to AUTO or GAS mode when there is no charging of the house battery. Running the refrigerator on 12 VDC will quickly drain the battery.”

In fact, the DM2672 refrigerator would drain a 100Ah battery to 50% capacity in about 60-80 minutes!

So a “3-way” fridge really isn’t. It’s effectively 2-way most of the time. To use the DC Mode, you need to either be plugged into shore power, running your engine/alternator, or powering a generator.* DC Mode should be reserved for emergencies or driving across town.

Either way, you probably won’t be impressed by the fridge’s cooling performance.

  • RV refrigerators are infamous for taking 8-12 hours to cool down from ambient temperatures.
  • Plus, they are much better at keeping food cold than making it cold. You don’t want to stick hot lasagna in an absorption refrigerator!
  • Absorption refrigerators can cool down to about 40 degrees below ambient temperature. So if you’re camping in 100-degree heat, you can expect your fridge to be … 60 degrees. That’s 22 degrees higher than a normal fridge!
  • Absorption refrigerators don’t always work well at higher elevations 6,000 feet and above.
  • And … your RV needs to be as close to level as possible to prevent damage to the fridge during operation.

If you’re a fairweather camper hopping from campground to campground, enjoying cool summer evenings, then you’ll be happy with an absorption refrigerator.

*Theoretically, you can run an absorption refrigerator off battery power for long periods with an upgraded battery bank, but there’s literally no reason to do that since it runs more efficiently off propane, anyway.

Option 2: Stick to Campgrounds and Enjoy a Residential Refrigerator

  • Cooling Performance: Excellent
  • Off-Grid Capability: Very Poor
  • Storage Space: Good
  • Cost: Low/Medium

If you want maximum cooling performance, your best bet is an AC residential or AC/DC marine compressor refrigerator.

You will mostly find residential fridges reserved for larger Class A and Class C motorhomes and a few luxury 5th wheels. They are rarely found in towables.

A residential refrigerator is … exactly what you’d expect. It’s a regular household refrigerator that’s been shoved into an RV. Residential refrigerators are popular amongst full-time RV travelers like the RVGeeks.

Some motorhome manufacturers include these as standard equipment, but most RV owners must do their own modifications. (Fun fact: Don’t assume any fridge will fit through your entry door!)

What’s not to love about a residential refrigerator?

  • They’re huge.
  • They’re sleek.
  • They have nifty features like ice makers and water dispensers.
  • They’re freakishly cold.
  • They actually freeze ice cream at the peak of summer.
  • And did I mention huge?

Just one problem … they draw a lot of power.

(Actually, two problems. You’ll need to install your own door latch.)

(OK, so technically three problems. The third problem is that they aren’t “designed” for RV use, and therefore the components could break due to the harshness of travel. But this concern seems mostly theoretical. While I wouldn’t put a residential refrigerator in an off-road camper, I wouldn’t think twice about installing one in a motorhome.)

Anyways, where was I? Oh yes, the big problem … power.

There’s no getting around this. If you want a Whirlpool refrigerator with French doors, a bottom freezer drawer, and an ice maker, you’re going to need to feed the dragon.

If you camp with hookups, that’s not a problem. Just plug in and say a prayer of thanks to Nicola Tesla.

If you camp in the boondocks … prepare to spend umpteen thousands upgrading to at least 300-400Ah of usable battery capacity (note I said usable, so double those numbers for lead-acid batteries). Plus a dedicated inverter.

Because they’re such power hogs, AC-only residential refrigerators are usually only found in motorhomes. But you can theoretically use them anywhere. Just understand that you’ll need to plug into shore power, run a generator, or invest a mortgage down payment into your batteries to use them.

Option 3: Buy a Boatload of Batteries and a 12V Fridge

Credit: Pleasure-Way
  • Cooling Performance: Good
  • Off-Grid Capability: Good
  • Storage Space: Excellent
  • Cost: Medium/High

In recent years, quite a few OEMs – Thetford, Vitrifrigo, Furrion, Dometic – have introduced 12V RV refrigerators. These fridges use high-performance 12V compressors (usually Danfoss).

Here’s how much power they draw:

  • The Furrion 16-cuft Arctic draws 11A @12VDC
  • The Dometic 10-cuft DMC4101 draws 13A @12VDC
  • The Thetford 8-cuft POLAR N8DC draws 7.9A @12VDC
  • The Vitrifrigo 5.3-cuft DP150i draws 5.4A @12VDC

While those are not small loads, they are far, far better than AC-powered residential refrigerators. The Thetford N8DC, for instance, could run off a single 100Ah lithium battery for over 12 hours!

12-volt RV refrigerators have some significant benefits.

  • They don’t need an inverter. They can run directly off battery power – even solar power!
  • They offer more usable space. The gadgetry of a 12V compressor fridge is much smaller than an absorption refrigerator. So for the same size cabinet, you get more internal storage space.
  • Little maintenance. Compressor refrigerators have no pilot light, no burner, no chance of vapor lock, etc.

So, what’s the tradeoff?

Here’s the thing – your stock battery bank probably isn’t big enough. You could drain your batteries in just one night of dry camping, let alone a weekend!

So most people who purchase an electric RV fridge will also upgrade their battery bank to at least 200Ah (lithium) or 400Ah (lead-acid). (Click here for why lead-acid batteries need to be twice as big.) Lead acid batteries will weigh more and take up more space. Lithium batteries are more expensive and must be protected from freezing, but they’re better for off-grid deep-cycle applications. Here’s a guide how to convert your battery bank to lithium.

Don’t expect this upgrade to be cheap. You could spend $2,000 just in parts!

Option 4: Bonus - a Portable AC/DC Fridge/Freezer!

ARB 12V Portable Fridge Freezer
Credit: ARB
  • Cooling Performance: Excellent
  • Off-Grid Capability: Excellent
  • Storage Space: Limited
  • Cost: Low/Medium

So far, everything I’ve discussed has been a built-in refrigerator, which includes full-height and under-the-counter units.

But there’s another option, one popular with car campers and expedition campers: the portable fridge/freezer.

These are units like the Dometic CFX Series, the ARB Classic Series II, and the ICECO brand. These portable fridge/freezers aren’t much bigger than an ice chest, but thanks to their high-performance 12V compressors, they can keep food cold in any climate!

And they hardly draw more power than a lightbulb. The ARB 50-quart cooler draws just 0.7 to 2.3 amps @12VDC.

(By the way, if all this talk about amp draw is confusing, check out my article “What’s My RV Appliance Amp Draw?”)

Now, if you’re thinking to yourself, “50 quarts isn’t big enough for a camping trip!” then I’m not disagreeing with you.

But as you’ve probably realized by now, upgrading to an all-electric built-in fridge can be prohibitively expensive if you dry camp.

If you only need to keep your ice cream cold, why not leave the absorption fridge alone and just bring along a small 12V fridge/freezer for the items that really need to stay cold? Keep the eggs and fruits in the absorption fridge; keep the beer and ice cream in the compressor cooler. Best of both worlds!

Ross

RV engineer by day, intrepid blogger by night (and occasionally weekends). This website is all about how RVs work, and sometimes why they don't. Bookmark pages that you find helpful, and join my email list for exclusive monthly awesomeness.