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Will an RV Fridge Run Off Battery While Driving? Maybe!

Will an RV Fridge Run Off Battery While Driving? Maybe!

“Will an RV fridge run off battery while driving?” We hear this question several times, and the answer is… maybe. But it depends on a couple of factors. Today we’ll answer the question based on the type of RV fridge you have in your rig.

What Is an RV Fridge?

You may have seen our post dedicated to the RV refrigerator. In that post, we describe several different types of RV fridges and how they work. We’ve also written a post on absorption refrigerators and a separate post answering the question, “What is a 3-way RV refrigerator?“.

In short, absorption refrigerators, commonly known as “RV fridges,” have been used in RVs for decades. They’re a great choice for this purpose because they can run on either electricity or on LP (liquid propane) gas. This is important because as RVers we need our refrigerators to continue functioning even when we’re not connected to a source of electricity.

Even if you’re not an avid boondocker like us, you still have to drive your rig down the road. So even if your trips are mostly from full hook-up to full hook-up, the advantage of a fridge that doesn’t require 120V AC power to operate still exists.

The back of an absorption fridge is shown

In the back of an absorption fridge, you’ll see coils, fins, and wires. An absorption fridge uses heat and a chemical reaction (ammonia, water, and hydrogen) to cool the unit. The heat can be provided by two or three different sources — 120V AC power, propane, or (in some models) 12V DC power.

One thing that is abundantly clear from all of our posts on fridges is that there’s more than one type available to RVers.

Most RVs generally have one of the following types of fridges:

  • 2-Way RV Fridge (runs on propane or 120V AC)
  • 3-Way RV Fridge (runs on propane, 120V AC or 12V DC)
  • 120V AC Residential Fridge (runs on 120V AC only)
  • 12V Compressor RV Fridge ( runs on 12V DC only)

All four of these types of RV fridges are powered in different ways. Two can be powered in two or three different ways depending on which type of power you select, while the other two can only be powered one way.

Depending on the type of RV fridge you have, this power source may be 12V power supplied by the engine’s alternator, 120V power from plugging into a campground shore power pedestal or with a built-in or portable generator, power supplied by LP (liquid propane) gas from your propane tank, or only by your RV house batteries.

Will an RV Fridge Run Off Battery Power While You’re Driving?

We all want to keep our RV fridge cold while driving, so this is important information. But again, the answer depends on which type of RV fridge you have in your rig:

3-Way RV Fridge

A 3-way RV fridge can run on 12V DC power, 120V AC power, or propane. Regardless of what mode you select to cool your 3-way fridge, the “brains” of the unit will use 12V DC power to control it. You should have no problem running your 3-way fridge off your RV batteries and alternator while driving.

Most 3-way fridges can be set to an “Auto” mode that will detect when the engine is running and will use power from the 12V battery(ies) and alternator to run the cooling cycle. (Depending on your fridge, you may need to select DC power manually.)

With a 3-way fridge, it’s unnecessary to drive with your fridge running on propane. This allows you to travel with the onboard propane tank(s) turned off if you choose to (or have to, such as when traveling on a ferry or through a tunnel), and still keep the fridge running.

A Class C RV driving down the road with mountains in the background

If your rig has a 3-way absorption refrigerator, an “Auto” setting should allow you to run the fridge off battery and alternator power as you drive (though some models may require switching to DC mode manually).

2-Way RV Fridge

A 2-way RV fridge can cool using either 120V AC power or propane. When set to “Auto” mode, the fridge senses whether you’re hooked up to shore power or running a generator, and switches to AC mode automatically. When you disconnect from power, it will automatically switch to propane mode. Either mode can be selected manually on many models (but of course you can’t use AC mode without AC power).

Like 3-way fridges, 12V DC power is required to run the brains of the refrigerator as well as the electronic ignition that lights the flame when a propane heating cycle begins. However, the fridge does not use the 12V DC power to cool.

So while you can technically use a 2-way RV fridge to run off batteries while driving, you’d actually only be running the brains/controls off battery power. The cooling would have to be done using propane.

This is where a controversy come in. While it’s not illegal to leave your propane tank turned on while driving, it is arguably less safe. That’s primarily because of the increased potential for fire or explosion in the event of an accident when an open propane tank is present. And some places (ferries and tunnels for example) may mandate that propane tanks be turned off.

To run a 2-way fridge while driving, you’d have to leave the propane tank valve open. If your RV is wired to allow it, you could run your rig’s refrigerator in 120V AC mode using the inverter, which technically means the fridge is running off the battery, enabling you to turn off the propane and still keep the fridge cool.

But this modification isn’t likely a popular one, since anyone looking to run their fridge on AC power all the time would likely opt for a residential RV fridge instead. The good news is that RV fridges are extremely well-insulated, so they stay pretty cool while turned off during a day of driving.

12V Compressor RV Fridge

A 12V compressor fridge runs only off of 12V DC power supplied by your rig’s battery(ies). If you’ve got a 12V compressor fridge, then it’s always running off of 12V DC power from the battery(ies), so yes — you can run your 12V compressor fridge off battery power while driving.

120V AC Residential Fridge

A 120V AC residential fridge requires 120V AC power to run at all times. An RV with a residential fridge will be wired so that it can run via the inverter, fed from the rig’s house battery bank. This means that you can run your 120V AC residential fridge off the 12V batteries while driving.

This is the residential fridge in our Newmar Mountain Aire. We could run this 120V residential fridge on battery power while driving down the road, thanks to our inverter.

So, technically, there is a way to run any RV fridge off battery power while you’re driving your rig down the road. How you achieve this may differ depending on what type of fridge you have.

While we’re on the topic of RV refrigerators, we keep an eye on the temperature in ours without having to open the door. We use an indoor/outdoor thermometer, with the “outdoor” sending unit inside the fridge (or freezer).

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If you’re wondering how we got our new fridge into our RV (or more specifically, how we got the old one out), check out the video below!

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gary

Monday 25th of September 2023

I do not pull my 5th wheeler with the refrigerator on ever. When I stop for the night, or at my destination, I plug it in (electric or propane). Also have a need help question, one of the preformed holders of shelves in the door have broke off. I have glued it several times, it holds for a while. Do you have any sugestion to fix it better?

TheRVgeeks

Monday 25th of September 2023

Bummer, Gary. Plastic can be tough to get repaired properly... especially if it's thin, since there's less surface area available for the adhesive to bond to. If the preformed piece is just a clip, we'd contact the fridge manufacturer to see if they can point you to a replacement. If it's a molded "ledge" that the shelf sits on, you may need to see if you can bond (epoxy?) a block of wood or something similar that would support the shelf.

Karen

Tuesday 19th of September 2023

We have a 3-way fridge. On a two-day drive from WA state to Arizona, we kept our fridge on battery while driving. We arrived at our destination with a nearly dead trailer battery. The fridge pulled so much power that the battery was gradually depleted. We tow a Casita with an SUV.

TheRVgeeks

Tuesday 19th of September 2023

Oh no, @Karen! It sounds like your issue is that there's not enough charging power (if any) coming from the SUV to the Casita when connected for towing (one of the pins in the 7-pin connector often provides 12V to the trailer battery). If your connector is providing 12V power, it's likely that the wiring is so small, the effective charging amperage is too low to keep up with the drain from the fridge. You may need to upgrade that system to ensure that more power is coming through (from increasing the size/gauge of that wiring to using a DC-to-DC charger inline to boost the output).

John C

Tuesday 19th of September 2023

I never felt comfortable having propane "on" while underway in my MH. I had my dealer add a 110V circuit off the inverter circuit, so I have 110V for my RV refrigerator while underway. The battery is charged off the alternator. I have never had any problems with this arrangement (so long as I remember to turn the inverter on before driving).

Joe C

Tuesday 19th of September 2023

Understanding the danger in an accident, I used to take my chances driving with the propane on for my 2-way fridge. Then when I realized it could be just as disastrous if you have a tire blowout or run over something that pops up and severs a propane line...I'm convinced to keep that propane valve closed!

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