Ice is nice—until you do the math. For an ice chest to efficiently keep your perishables cool, you need twice the volume of ice as the volume of food and drink. That means, for most coolers, only a third of the available space can be used for supplies; the rest needs to be devoted to ice.
Enter the electric cooler, which functions like a portable refrigerator or freezer that plugs into your car, a generator, or a large portable battery. These devices don’t need ice, so nearly the entire interior space can be used for your comestibles. I say “nearly” because you need to leave gaps between items so air can flow amongst the brisket and brewskis. Usually, the different shapes of the items naturally create enough space between themselves to let the cold air circulate.
Both designs share the same off-grid problem: the coolant, whether ice or electricity, will run out at some point, ideally not before you’ve consumed all the food and drink or before the trip ends.
My family and I have been testing ice coolers and electric fridge/freezer units for years now on various road trips and car-camping journeys. After squeezing the four of us, plus luggage and gear, into our family’s midsize SUV, I am ready to ditch the space-hogging large ice cooler.
My Favorite Electric Cooler
I've become completely enamored with electrics and have come to favor the Dometic CFX3 series—now in their third generation with great improvements over the previous versions. They work incredibly well as fridges or freezers—they can be set as low as –7 degrees Fahrenheit for deep-freeze needs.
Dometic offers six sizes in its CFX3 series ranging from a compact 36 liters ($900) to a massive 100 liters ($1,400). All of them run on AC power in the house or DC power in the car. The best model for us has been the CFX3 45 ($960). It has the same footprint as the next-smallest model, but it’s just a few inches taller to provide ten extra liters of volume. It fits perfectly along the side of the cargo space in our vehicle and has proven to be rugged enough to tolerate the haul to and from the campgrounds as well as the lid-slamming abuse of our three- and six-year-olds.
Road trips are where these units shine. They can be plugged right into the vehicle’s power supply, and as long as the car is running, they don’t drain any power from the battery. (For those nit-picking, it does make the alternator work a touch harder, which subtracts the tiniest fraction from your gas mileage.)
For overnight stops, Dometic has built in a three-stage voltage monitoring system so a cooler will switch itself off once the source battery (your car’s) depletes to any of three predetermined levels. On cold nights, this isn’t really a big deal since the compressor doesn't need to work that hard (if at all) to keep your food cool. In warmer weather (say, with an overnight low of 55 to 65 degrees Fahrenheit) the cooler may end up getting cut off from the car battery power, but the insulation of the cooler itself will still keep the contents safe.
Great External Batteries
Once the overnight low starts to get above 65 degrees on a trip—and depending on how late you sleep in and let the morning sun warm the interior of the vehicle—you need to be more careful with your cooler. The simplest way to save your supper on an overnight trip is to just take your electric cooler into the hotel room and plug it into an AC socket for the night. Of course, that’s not feasible if you’re nowhere near an outlet, never mind a hotel.
The other option is to use an external battery, separate from your vehicle, that you set up to run the cooler. Goal Zero is a well known brand in this space and I have used the Yeti 500X ($700) and, for camping trips when we weren’t running the car every day, the higher capacity Yeti 1500X ($2,000) to power the cooler. Those lithium batteries used to be troublesome, but Goal Zero’s new X series 12-volt sockets work great with the coolers and include USB-A, USB-C, and an inverter for AC power.
Dometic makes its own battery, the PLB40 ($850), which includes a 12-volt socket as well as USB-A charging ports. This is a 500 watt hour battery, which is the same capacity as the Goal Zero 500X. While Dometic's battery lacks USB-C and AC sockets, it does have a threaded two-pin 12-volt socket to ensure the cooler plug doesn't wiggle loose as you bounce around on rough roads.
The beauty of both of these battery systems is their ability to provide pass-through charging. This means the cooler can stay plugged into the battery, and the battery can stay plugged into the vehicle. So, after the portable battery gets partially drained overnight while keeping the cooler running, the car’s battery, via the alternator, can charge the battery the next day while you’re on the road. Meanwhile, the constant supply of power from the car to the portable battery keeps the cooler running. One hiccup is that when you plug either of these external batteries into your car, you don’t get the benefit of the cooler’s battery protection system. Either battery will just keep drawing power from your car’s battery if you leave it plugged in. So be sure that it’s plugged into a socket that is only active when the ignition is on, or just remember to unplug the external battery from the car if you need to run the cooler overnight.
Tap Dometic's App
With the third generation of the CFX coolers, launched February of 2020, comes a brand new CFX3 app. While the previous version of the Dometic app was worth avoiding, the company made notable improvements this time. The coolers can now connect to a phone via Bluetooth, directly via Wi-Fi, or through an existing Wi-Fi network. These options for connecting to the cooler are the standout upgrade with relation to the app. The previous generation of cooler only emitted its own Wi-Fi signal, forcing the user to switch to the cooler's discrete network in the phone’s settings.
The app has the same expected feature of being able to see and adjust the temperature of the cooler. For energy consumption analysis, the new app shows the history of the temperature in the cooler as well as the power consumption required to maintain that temperature. It's useful for longer term off-grid battery management to see how much power the cooler pulls. This helps you calculate how big of a solar panel array is needed to keep the cooler powered up. I mostly just check the app to make sure the cooler is running properly after I've packed it into the back of our vehicle, where the screen on the cooler may be obstructed. Also, the readout on the new third generation of coolers dims after a short while, making it harder to see if it’s on and working.
There’s still room for improvement with the app, however. First, while it does indicate an open lid by subtly changing the graphic representation of the cooler in the app, it does not have a push notification to inform the user when the lid is left open for an extended period. The app only shows a small “alert” text after the lid has been open for three minutes. I’d like to be able to change the setting for that alert so it fires in fewer than three minutes. Related, but a reach beyond the app itself: the only notification that the lid has been left open is a flashing light on the inside of the cooler (again, only after three minutes). But there is no audio alert, and the lid has to be opened more than about half an inch in order to trigger this warning.
The other feature I wish the cooler and app had would be to send an alert when power is cut off from the cooler. This would require a small battery to keep the Bluetooth or Wi-Fi connection alive after the cooler’s main power is interrupted to be able to send the alert, so that reaches a little beyond just the functionality of the app itself.
Electric Versus Ice Cooling
Naturally, all this iceless convenience comes at a price. These devices cost hundreds of dollars, and if you get a bigger cooler, prices quickly climb over $1,000. I ran some numbers to compare my use of the $960 Dometic CFX3 45 against two high-performance, rugged ice coolers: the $450 Yeti Tundra 75 and the $420 K2 Summit 90. I chose those ice coolers because they have roughly the same capacity of the CFX3 45—that is, how much food and drink the coolers can hold using the recommended 2:1 ice-to-contents ratio.
When I add up the cost of all the bags of ice I’d have to buy for, say, three camping trips per year, I can calculate that it would take me 10 years before I made up the cost difference of the electric cooler. That may sound like a very-long-term investment, but these electric coolers are popular in Australia and have easily lasted that long in fairly rough conditions (and I haven’t been particularly gentle with my test coolers). Add to that some non-camping road trips where lunch supplies can be bought at a grocery store instead of a restaurant and that cost delta starts to shrink. Not to be forgotten is the fact that you’ll never deal with soggy milk cartons or cheese that has marinated in your melted ice water (along with whatever schmutz has been washed off of your beer cans).
For an off-the-grid car camping trip, things get a little more complicated. If you go with ice, are you trying to go the whole stint without refreshing the ice, or does the trip include hitting up the local store for a refill? How much gas and time does that cost? If going electric, will a large battery or a solar panel keep enough charge flowing? That can ratchet the price up quickly.
Much like the debate over the value of a $50,000 Sprinter van instead of 500 nights of $100 hotel rooms, it depends on your situation—and what you’re willing to pay for the convenience. If you’re looking forward to lots of road trips and camping adventures, an electric cooler will be worth it and will take up less space in your cargo hold in the process.