Dometic CFX3-35 12V Cooler

I’ve mentioned my Dometic CFX3-35 12-volt cooler a few times during the two years that I’ve had it, starting with the kick-off for a coast-to-coast road trip. I’ve even published videos dedicated to it. But I had not shared an article here until now. Our coast-to-coast road trip took place during the height of lock-downs and restaurant closures. With that, combined with my wife’s diet restrictions, we knew that we needed to carry our own food as much as possible. Dometic is a popular brand among some of the overlanding YouTubers whose videos I enjoy. So, I started my search there and quickly settled on the CFX3-35, their largest cooler that would fit beneath my car’s parcel shelf for concealment in the trunk.

Dometic markets their units as “coolers” although they have capabilities very much like those of refrigerators and freezers. I will use the terms “cooler,” “refrigerator,” and “fridge” interchangeably in this article. Dometic’s CFX3 line of products will chill their interiors to between 50°F and -8°F at external temperatures between 61°F and 110°F. Results during my testing was fairly consistent with those figures. For example, the cooler will not cool to below freezing if the car’s interior is very hot. Likewise, it’s difficult to control spot-freezing if the fridge is set to 38°F and running in the car overnight on a cool, 40-degree evening. I’ll touch more on that later.

In addition to concealment, the trunk was a great location due to convenient access to a 12V outlet that’s back there. However, getting food in and out was not convenient because we had to rotate the unit and pull it outward to open the lid. It wasn’t a terrible task, but could be a little more difficult when the fridge was fully-loaded. A lot of off-roaders install a slide rail system to bring their cooler out of the vehicle and toward them. That’s certainly a convenient option; however, a slide rail setup would make the installed height of the cooler too tall to fit beneath the parcel shelf, especially since the system would have to be tall enough to clear the lip of the hatch opening. I came up with a new plan.

Very seldom did I have a passenger behind the driver’s seat. I’m tall enough to leave very little room behind the driver. So, I created a fold-down platform which replaced the rear driver’s side seat back. The CFX3-35 is a perfect fit behind the driver’s seat in my GTI with the rear seat back removed. The overhead clearance is too low to open the lid completely, but it’s sufficient for loading small-to-medium objects. This photo shows the fridge with its black protective cover installed. It is NOT an insulating cover. I use the cover for improved concealment now that the cooler is more visible than it was in the trunk.

“Why carry a refrigerator in a small car? Do you camp or travel a lot?” The honest answer is NO. As mentioned above, I bought it for what turned out to be TWO trips from Virginia to California and back. I also used the refrigerator and a microwave oven on a ham radio expedition of sorts where I knew that I’d be far from convenient eating options. I shared that story here. For the most part, the fridge is relegated to trips to the grocery store once or twice a week. It’s been fantastic for that! Set up as a freezer at 0°F, I can load up to 38 quarts of frozen goods during my usual morning drive and have no concern about rushing home to get my stuff into a home freezer. It’s also great for potlucks and other day trips.

It was even easier to keep the fridge in the car full-time once I committed to permanently removing my rear seat. Having it with me most of the time has been more convenient than I expected. Even on a hot day and with the fridge off, it can cool to 60°F in about 15 minutes and then to 40°F in about 30 minutes. Reaching below 30°F takes about an hour, should I want to move something that needs to be frozen. That time is drastically reduced if I cool the unit to around 50°F ahead of time. For example, I often cool the fridge to 50°F the evening before a grocery store visit. Setting the temperature to 0°F before leaving home in the morning will often result in the fridge reaching 20°F or colder before I bring food out of the store.

What are the drawbacks of having a fridge in my car? Well, space is an obvious drawback in a small car. Still, I’m a bit surprised that fridges haven’t become more commonplace in minivans. But that may be because of the greater drawback of power consumption. The truth is that it’s not a great idea to power a refrigerator from the vehicle’s starter battery for extended periods. The CFX3 draws little current when operating as a cooler (50°F) in moderate weather. That changes drastically when set as a freezer during the summer. The compressor will run continuously and drain a 100-Ah battery in about 13 hours. This photo was taken during my second trip to California. Notice that I was powering the fridge from a Jackery power source. The Jackery would charge while the engine was running and then power the fridge overnight.

These days, I power my CFX from my 1280-Wh LiFePo4 battery. Even with the extra capacity, the endurance is good for about a weekend unless I drive the car or recharge with household power. Having the fridge does require extra attention to avoid being stranded with a dead starter battery, which is impossible with my setup. The average driver simply does not pay attention to that kind of data. So, it’s probably best to NOT include refrigerators as standard equipment since they could lead to disappointment with uninformed owners. I mentioned cooling on hot days in the second paragraph. It’s not uncommon for a vehicle interior to reach 120-140°F on a hot days. The fridge will not cool appropriately in such an environment. I mitigated excessive heat in my car by using a set of Weathertech insulated sunshades. See this video for details.

Let me know what you think. Would YOU like having a refrigerator in your car? Or is this simply another wild idea that proves my overall insanity? 😉

Keeping Cool,


About Scott

I grew up near Houston, TX and served in the U. S. Coast Guard for over 30 years. I have an electronics background and continue to work in the electronics engineering field. I taught myself the basics about automotive systems as well as how to perform some of my own maintenance (cars and bicycles). I became involved with Amateur Radio and computers in 1995. The explosion of technology has made my job and several of my hobbies quite interesting. My hobbies include Volkswagens, bicycling, photography, electronics, amateur radio, web management, and reptiles. Visit my websites to learn more.
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