For as long as most of us can remember, caravan fridges have utilised three-way absorption technology. And from a versatility point of view, it’s hard to beat.
The 12V option ensures that your food stays cool on the move. Then you can switch over to the mains when you’re on hook-up, or use the gas if you’re off-grid. However, the technology isn’t without drawbacks.
First, in 12V mode, performance often suffers. It may be sufficient to keep the fridge cool enough in the UK, but could result in temperatures inside the fridge climbing a little too high when negotiating hot Continental autoroutes.
In fact, absorption technology generally is pushed to the limit in hotter climates, sometimes struggling to keep up if ambient temperatures climb above the mid-30s.
And then there’s the issue of freezers. Absorption-powered freezer sections tend to be tiny. Fine for the odd tub of ice cream and ice-cube trays, but that’s largely it.
So if you want better refrigerator performance when abroad, or simply want to take a freezer full of frozen food away with you, what are your options?
How about a portable fridge/freezer?
An increasing number of us have turned to portable, compressor-based fridge/freezers for use on our caravan holidays. Sometimes they’re called compressor boxes, and 4×4 aficionados have long referred to them as ‘expedition’ fridge/freezers.
But, essentially, they’re high-spec coolboxes with freezer levels of insulation and the same compressor-based technology as your refrigerator or freezer at home.
Practically all come with mains and 12V leads, and most can cope with 12-24V DC and a very wide range of AC mains voltages.
Naturally, the temperature is selectable so they can be used as a fridge or a freezer. And, being portable, they’ll happily sit on the floor in your awning.
But what about gas and off-grid use?
Well, first of all, none of these units run on gas. But off-grid use is possible because the units are so incredibly efficient.
Whereas a decent-sized three-way fridge will often sap a continual 10A, or more, from a leisure battery, most of the compressor boxes take 2-4A and the compressor only runs occasionally.
To bring this fully into focus, that 10A example just mentioned obviously consumes 10 Amp Hours. The least-efficient product in the test here takes just 1.2Ah, and that’s maintaining a temperature of -5ºC in very warm conditions. Fridge temperatures in cooler conditions would reduce electrical thirst further.
Because these units are so electrically efficient, a decent-sized leisure battery will almost certainly be able to maintain them for a day or two off-grid. And even a modest solar set-up should keep up with them for entire trips away from electric hook-up.
How we conducted our group test
We kicked off by cooling each unit to -5ºC (a suitably cold freezer temperature for most short- and medium-length trips), and then placed them in a room heated to 27ºC.
Over the following hour we logged exactly how long the unit’s compressor ran to maintain temperature, and measured the 12V current it consumed during the hour. From this we calculated how many Amp Hours each product used in total.
Weight and overall size are always issues with anything we take away, so we made sure that the units were as compact as they could be for their internal capacity.
Talking of which, some models have a stepped interior (the compressor and unit’s workings being housed beneath the step). Because the unit normally maintains the deep section’s temperature, this usually means the higher section – above the step – is warmer.
To keep that suitably cold, it becomes necessary to make the main section of the freezer colder than ideal – wasting energy. For this reason we prefer plain, non-stepped interiors.
Another important feature for these units is a built-in battery monitor, which cuts off the unit when it senses that the battery is getting low. However, it’s vital that the monitor is adjustable or can be overriden.
Why? Well, if, for example, at the end of a couple of days off-grid the unit is crammed full of expensive food, but the battery is low, most of us would prefer to risk the battery for an hour or so rather than lose the food. After all, no permanent harm will be caused to the battery if the alternator, or an electric hook-up supply, will soon be charging it up again.
Waeco CoolFreeze CFX 50 – five stars
Practical Caravan group test winner
- Price: £649.95
- External dimensions: 45x55x65cm
- Weight: 20.4kg
- Web: www.dometic.co.uk
Forget the 50 in the name, this box’s actual capacity is one behind the ARB at 46 litres. Granted, the CFX 50 is a tad bigger than the ARB but it’s lighter and we can forgive its slight portliness because it’s so frugal – slotting neatly between the National Luna and Engel, requiring 0.74Ah for our test period. This makes the A++ energy rating completely believable.
Performance aside, Waeco really packs in the features for the price. As in the ARB you get an internal light, a drain plug, and a sophisticated adjustable battery monitor.
But the CFX 50’s minimum temperature is -22ºC rather than the ARB’s -19ºC. And while the lid cannot be simply removed, it only takes a few minutes with a screwdriver to swap the hinges to the other side for maximum versatility.
Euroengel Mobile FlexCool 14F – three stars
- Price: £1224.99
- External dimensions: 80x50x50cm
- Weight: 26kg
- Web: www.eberspaecher.co.uk
With 56 litres of single-level chamber available, this box could sustain a whole family for a good few weeks. Especially because its -24ºC minimum temperature is well below the -18ºC needed for deep freezing.
Its enormous capacity factored in, though, this is still a physically big box externally. Part of the reason is the thick, heavily insulated walls, which meant the compressor ran for less than 10 minutes out of our test hour. But overall efficiency is good rather than outstanding because of the compressor’s 4-8A thirst.
Although the size, pleasing quality, and the premium Danfoss compressor help justify the high cost, it’s annoying at this price level to have no interior light, drain plug, or easy control over the battery monitor.
National Luna Classic Aluminium 40l – four stars
- Price: £1004.70
- External dimensions: 60.5x40x51cm
- Weight: 23kg
- Web: www.expedition-equipment.com
With a minimum temperature of -30ºC, you’d struggle to find ambient temperatures high enough to prevent this box reaching and maintaining -18ºC deep-freeze conditions.
Better still, this portable fridge couples incredible performance with excellent efficiency. Easily the most frugal here, it consumed just over half an Amp Hour in our hour’s test.
While undoubtedly a great and feature-laden piece of kit – a light and adjustable battery monitor are built-in – is it the best for caravanners?
Well, the aluminium case looks great and the thick walls boost efficiency, but they also make this unit a touch big and heavy considering its 39.8-litre storage capacity.
Engel MT35F – two stars
- Price: £599.99
- External dimensions: 62x40x37cm
- Weight: 21kg
- Web: www.bainbridgeint.com
Engels have a proven reputation for performance and durability. Their unique slide-motor compressor is frugal, amazingly durable, because of having only one moving part, and works better than most when the leisure battery’s getting low on charge.
But this box’s efficiency was good rather than excellent in our test, mainly because it ran for 20 minutes out of the hour, gobbling up 0.92 Amp Hours.
The box feels a little dated compared to the competition: the metal housing is smart but makes the unit heavy for its 32-litre capacity. The lack of light and a battery monitor are surprising, too.
But we like the removable lid, which slides off its hinges when opened, and the un-stepped storage bin.
ARB fridge-freezer 47-litre – four stars
- Price: £714
- External dimensions: 50x38x70cm
- Weight: 22kg
- Web: www.devon4x4.com
We were initially disappointed when this portable fridge powered up for a lengthy 16 minutes, but that was it for the entire test period. Because the compressor isn’t the most modest here, though, those 16 minutes consumed a group high of 1.2 Amp Hours.
But while this isn’t the best choice for off-grid use, it has plenty of redeeming features. The generous 47-litre capacity stacks up very well against the external size and weight.
You also get a drain plug – for easy defrosting – a removable lid, and a light. A clever storage basket, with one high side, also means you can easily split the stepped compartment into two or leave it as one, depending on whether you place the high side by the step or the outer wall.
Indel B 30-litre fridge – three stars
- Price: £451.02
- External dimensions: 59x38x35cm
- Weight: 16kg
- Web: www.expedition-equipment.com
The cost is hardly cheap, yet this 30-litre box is practically a budget entry compared to most here. But the reduced price doesn’t mean a lowly spec.
Rather unexpectedly, Indel uses premium Danfoss compressors – just as Euroengel and National Luna do. And with a smart LED light, a sophisticated three-level battery monitor, and a minimum temperature of -22ºC there’s not much evidence of skimping to meet a price in other areas, either.
The low weight and compact size also make the unit ideal for most caravanners but, we suspect, at the cost of insulation thickness. This is borne out in our test. The compressor ran for 17 minutes in total, making it second only to the ARB in terms of electrical consumption.
Mobicool FR35 – four stars
- Price: £349.95
- External dimensions: 58x36x40cm
- Weight: 13kg
- Web: www.mobicool.com
It’s hardly an industry secret that Mobicool is Waeco’s budget arm, and the FR35 – the cheapest conventional product in the group – is very tempting for a lot of us.
It’s relatively compact and very lightweight, given its 31-litre capacity. But unlike the other budget entry here, the Indel B, this doesn’t seem to be at the cost of efficiency. At 0.79 Amp Hours for our test period, this is only slightly behind its all-conquering Waeco cousin.
With a decent battery monitor and a compartment light included, we can hardly say that Mobicool has skimped on the spec either. Really, the only sticking point here is the -12ºC minimum temperature of this portable fridge/freezer.
That rules out deep freezing completely, but doesn’t mean that the unit will struggle to stay below zero in warmer climates.
Mobicool CK40D – star rating not applicable
- Price: £210
- External dimensions: 45x50x51cm
- Weight: 22kg
- Web: www.mobicool.com
A 40-litre capacity and cheap, so what’s the catch? And why have we given it no overall score?
Well, it’s different to the rest of the products here: although this unit is portable and efficient, the compressor side of it only runs on mains. But there’s also a thermoelectric cooler built in for when only a 12V supply is available. While the compressor circuit will chill the box down to -15ºC, the thermoelectric side will only dive down to 20ºC less than ambient temperature – usually way above freezing point.
If you use sites with hook-up, the CK40D is a great portable fridge for use in awnings that, in hotter climes, will maintain temperature better than most three-way models.
In transit, the levels of insulation, plus the thermoelectric circuit, will prevent the contents getting warm. If you buy frozen goods after arriving on site, the CK40D makes a great budget freezer.
Over an hour we logged how long the unit’s compressor ran to maintain temperature