Cool Runnings
You demanded it, so here it is - the 4WD Action mega fridge-freezer comparison!
If you ask four-wheel drivers what their favourite or most-prized accessory is, a large proportion will likely tell you it’s their fridge. Maybe this shouldn’t seem so surprising, because one of the real pleasures of outback travel is unwinding from a long day’s driving with a cold beverage - alcoholic or otherwise. And while an icebox is effective so long as you can replenish it every few days, for consistent, controlled cooling, youijust can’t go past an electric fridge.
It was a couple of years ago that we brought you our previous fridge comparison. That edition went on to become our most sought-after back issue, and given that it sold out some time ago, we felt the time was ripe to revisit the subject. While a wide variety of sizes and styles are available on the market, for practicality’s sake we confined ourselves to two main size brackets - 40L and 80L internal capacity, or the closest models to those sizes. We also only included proper fridge-freezers (not thermoelectric coolers), as anything less just won’t cut it when it comes to extended operation in the bush. What we’ve done here is to bring together a selection of quality fridges and subjected them to a controlled laboratory test to try to find how each performs under identical circumstances. There aren’t any losers in this test - all the fridges tested here are quality units. Our real intention is to help you determine which one best suits your needs. Did they manage to keep their cool, or did they throw in the towel when the heat was on? You’ll just have to read on and find out.
FRIDGE PHYSICS
Regardless of what exact mechanism they use, all fridges are essentially alike in that they are really heat pumps. They take heat (which is actually just energy causing atoms to vibrate) from within the refrigeration cabinet and dump it outside, thus making it colder inside the fridge than outside. Thermodynamics (there’s that word again) dictates that when you compress something, it gets hotter (because the same amount of thermal energy is now packed into a tighter space), and when you let it expand, it gets colder.
It also dictates that heat flows only from hotter things to colder things (never the other way around). All the fridges tested this time around used compressor motors (much like your fridge at home). This design compresses refrigerant gas into a liquid, making it hot. A heat exchanger on the outside of the unit lets the refrigerant dissipate this energy into the atmosphere, allowing it to cool to near-ambient temperature (most fridges incorporate a fan to assist with this process). It then passes into a low-pressure heat-exchange plate within the refrigeration chamber, where it expands, evaporating and becoming colder than the contents inside the fridge. Heat flows from the warmer contents of the fridge to the colder refrigerant before the refrigerant is pumped out of the chamber and back through the compressor where the cycle repeats.
TESTING METHODOLOGY
The single most important criterion in testing fridges is whether they keep the contents cold - nothing else counts for much if at the end of the day your beer is warm and the meat has gone off. Accordingly, we wanted to subject them to a thermal test to see how they fared at a range of temperatures. A secondary criterion is how much power each fridge uses in order to do its job. While it’s not absolutely critical, all things being equal it is preferable to have an economical fridge because it will be less demanding on the vehicle’s battery when the engine isn’t running (such as overnight). My original plan for the test was to get a bunch of blokes together one afternoon, load up the fridges with beer, then sample the golden ale from each fridge until we had determined beyond a shadow of a doubt which one performed best. While that would have been fun, it would, in all likelihood, have produced unreliable data. Instead we opted with a controlled laboratory test, trying, as much as possible, to replicate how people actually use their fridges in the wild. So we went back to the test chamber we used last time at the Australian Defence Industries facility in western Sydney. A company called Vipac now controls the climate test chamber, but thankfully it was willing to help us out. Vipac has at its disposal a National Association of Testing Authorities (NATA) approved, climate-controlled chamber, which has an operating temperature range of between -37ûC and 90ûC. For the duration of the test, the fridges were placed inside the chamber so they could all be subjected to the sorts of temperatures you’re likely to encounter out in the bush.
 |
We set the lower and upper temperature extremes at 15ûC and 55ûC respectively. It can actually get much hotter inside a vehicle sitting in the sun on a summer’s day, but we didn’t want to risk causing damage to any of the fridges. Accurate testing is all about eliminating undesirable variables, leaving only what you’re trying to test. The three main things that impact on fridge performance are ambient air temperature, the volume and temperature of the fridge contents, and how much current the fridge is receiving from a power source.
Accordingly, each fridge was loaded with an identical quantity of food, consisting of 2L of milk, a loaf of bread, a sixpack of tinnies and a tub of margarine. Where units had a separate freezer section, we tossed a bag of frozen peas in there. This is important, because it means the fridge actually has to chill food and not just air. They were placed inside the test chamber on pallets so the cooling effect of the concrete floor wouldn’t affect the test. The power leads going in and sensor wires going out all passed through ports in the side of the chamber that were sealed up with rubber bungs.
A CURRENT AFFAIR
It is absolutely critical for a fridge’s operation that it receive sufficient current. Whereas, for example, driving lights connected with dodgy or thin wire will be a bit dimmer than properly wired units, if a fridge can’t draw enough current from the battery, then it will simply not function. It’s important to appreciate that electrical resistance has a much bigger impact when you are operating on 12V instead of 240V. Basically, the longer the wire, the more voltage will be lost along the way. For this reason (and because we had a number of powerful fridges in the field), all fridges were powered through quality 8mm2 cross-section, single-core wire. That equates to a maximum operating current of about 85A. While many of the smaller fridges would have happily run on 6mm2 cables, we had to work from the highest common denominator in order to compare apples with apples. All the wires were cut to an identical length (about 5m) with eyelet connectors crimped onto the ends.
The plugs were cut off the end of all the fridge power leads and they too, were fitted with eyelet connectors. In order to measure the current draw of each fridge, we elected to use calibrated shunts, which work by measuring resistance. The positive wire from each fridge was connected to one end, with the other end going to its power supply. The small wires coming off each (see photos) are 4mm2 dual-core running to an Hioki 8421-01 16-channel data logger (with trick colour display!), which records the resistance in milliohms. Using Ohm’s law (voltage divided by resistance equals current, or V Ö R = I), we were able to calculate the amount of power each fridge was consuming. Because the measurement is so small, we were careful to solder all the wire ends and make sure connections were tidy, because any extra resistance could skew the results.
The negative lead from each fridge was wired up to a shared earth (one for each power supply). Electricity came in the form of a trio of Sorensen DCS60-50 power supplies. Each of these industrial-grade units can supply up to 50A, which is plenty given that most of the fridges were fused at 10A. The Sorensens were set to output at 13.8V, which is what a healthy vehicle battery will produce while it’s being charged by the alternator - basically as if the engine were running.
HOT STUFF
We started the fridges running a day before actual testing began, because they typically take some time to draw down to their set temperature and get settled into a steady operating cycle. It also gave us time to monitor internal temperatures and get their thermostats set so they stayed within a few degrees above freezing (a fiddly job in itself).
The temperature profile roughly approximates an outback summer’s day. It started, and with four hours at 15ûC, took six hours to climb to a peak of 55ûC, where it stayed for four hours, before descending over another six hours back to 15ûC, which it stayed at for the final four hours. Hioki 3641-20 temperature and humidity loggers were used to measure temperatures inside the fridge and freezer sections throughout. Each had a sophisticated temperature sensor, which was suspended midway down inside each section, endeavouring to keep them away from heat-exchange plates, which might give a lower reading than was actually the case.
ARB - MT45FARB
In case you hadn’t picked it, the ARB fridge is identical to an Engel MT45, which is why we have reprinted the Engel’s results. Steel construction makes it a solid unit, though it is inevitably more prone to suffering corrosion as the years roll by, and it’s heavier than similar-sized plastic and fibreglass fridges. Test performance was good, with the temperature staying steady until above 40ûC, at which point the compressor switched on permanently until around the 18-hour mark, when it resumed cycling. Current draw was good, with overall amps on par for its size category.
Total capacity: 40L
Fridge capacity: 40L
Freezer capacity: N/A
Construction: Melamine-coated steel
Insulation: Polyurethane Dimensions [L x W x H]: 631 x 360 x 508mm
Weight: 24kg Input power: 12-24V, 240V
Compressor: Sawafuji Swing Motor
Assembled in: Thailand
Warranty: 3 years
RRP: $1199
|
|
BUSHMAN
The Bushman is one of the cheapest units in the field, and given its performance in the test, represents good value for money. For the purchase price, you get both the 35L and the 42L lids, two internal baskets and a 240V adaptor. The digital control panel works well. Our only gripe with the design is that the handles rotate through 180û, which means your knuckles get crushed while carrying the unit. It had a very good test performance with the 42L lid fitted. The Bushman had the lowest ampere-hour figure at 15ûC, consuming a tiny 0.61Ah. Total consumption was also excellent at 26.2A.
Tel (02) 9834 6444
www.bushman.com.au
Total capacity: 35L/42L
Fridge capacity: 35L/42L
Freezer capacity: N/A
Construction: Powdercoated steel with polycarbonate liner and lid
Insulation: 35mm
Dimensions[L x W x H]: 660 x 385 x 470mm
Weight: 20.5kg
Input power: 12-24V
Compressor: Danfoss BD-35F
Assembled in: China
Warranty: 3 years
RRP: $990
|
|
ENGEL MT45
Everything we said about the ARB applies here, too. Earle from 4WD Warehouse commented on the high quality of the 12V cable. We also liked the digital thermometer. Along with its ARB twin, the MT45 is unique in the field in being powered by a Japanese-built Sawafuji Swing Motor. Test performance was good, with the temperature staying steady until above 40ûC, at which point the compressor switched on permanently until around the 18-hour mark, when it resumed cycling. Current draw was good, with overall amps on par for its size category.
Tel 1300 302 653
Fax 1300 2 ENGEL (1300 236 435)
www.engelaustralia.com.au
Total capacity: 40L
Fridge capacity: 40L
Freezer capacity: N/A
Construction: Melamine-coated steel
Insulation: Polyurethane
Dimensions[L x W x H]: 631 x 360 x 508mm
Weight: 24kg
Input power: 12-24V, 240V
Compressor: Sawafuji Swing Motor
Assembled in: Thailand
Warranty: 3 years
RRP: $1199 |
|
EVAKOOL RF47-DT
The two EvaKool units are based on the company’s range of iceboxes, which is why they’re constructed entirely from fibreglass. Presumably, the glossy white finish would reflect more heat when the fridge is in the sun compared with darker finishes. The freezer section has an acrylic lid. A 240V power pack is $159 extra, and a single-zone version is also available. Fridge performance was good, staying well below 10ûC, even when the chamber temperature was ramped up to 55ûC. The freezer compartment maintained a very consistent temperature, never climbing above -9ûC. Current draw was marginally greater than for similarly sized single-zone fridges.
Tel (07) 5492 7777
Fax (07) 5492 7733
www.evakool.com.au
Total capacity: 47L
Fridge capacity: 25L
Freezer capacity: 22L
Construction: One-piece moulded fibreglass
Insulation: 40mm polyurethane foam
Dimensions [L x W x H]: 725 x 445 x 420mm
Weight: 17.5kg
Input power: 12V
Compressor: Danfoss BD-35F
Manufactured in: Australia
Warranty: 5 years on cabinet and fittings, 2 years on compressor and electronics
RRP: $1099 |
|
EVAKOOL RF85-DT
The RF85 is basically identical in design and operation to the smaller RF47. It is longer and narrower in comparison with other fridges in the 80L category, which may suit some vehicles better than a squarer design. Control is via a simple knob with a high-low power switch. In testing, we found that while the power light came on, the unit was not actually cooling. The problem was traced to a faulty thermostat (a Danfoss part), which was replaced, allowing the fridge to function properly. Fridge performance was reasonable, getting a little warm overall at peak chamber temperature (keep in mind that in the real world you can adjust the thermostat to compensate). The freezer compartment performed very well, cycling at around -15ûC and peaking at -11ûC. Current draw was reasonable given that it was the largest-capacity unit tested.
Total capacity: 84L
Fridge capacity: 42L
Freezer capacity: 42L
Construction: One-piece moulded fibreglass
Insulation: 40mm polyurethane foam
Dimensions [L x W x H]: 1110 x 440 x 435mm
Weight: 21kg
Input power: 12V
Compressor: Danfoss BD-50F
Manufactured in: Australia
Warranty: 5 years on cabinet and fittings, 2 years on compressor and electronics
RRP: $1549 |
|
EXPLORER DC-56
The distinctive-looking Explorer fridges are constructed from aluminium and fibreglass with four heavy-duty handles/tie-downs. They are the only dual-zone fridges with separate thermostats and also feature a high/low power switch and adjustable latches. The lead is hard-wired to the unit. Our only minor grumble is the lack of internal storage baskets. In testing, the DC-56 and DC-70 were almost impossible to separate. This isn’t entirely surprising, as they are mechanically identical and only differ in the height of the units, resulting in a 14L difference in capacity. The fridge temperature stayed below 7ûC, and the freezer kept the peas nicely frozen. Power consumption was lineball with its (slightly) bigger sibling.
Total capacity: 56L
Fridge capacity: 36L
Freezer capacity: 20L
Construction: Marine aluminium exterior, fibreglass interior
Insulation: 75mm polyurethane foam
Dimensions [L x W x H]: 820 x 500 x 420mm
Weight: 23kg
Input power: 12V (separate 240V inverter included)
Compressor: Danfoss BD-35
Manufactured in: Australia
Warranty: 3 years on cabinet, 1 year on compressor and controller
RRP: $1895 |
|
EXPLORER DC-70
The DC-70 is identical in footprint to the DC-56, only deeper. It has the thickest insulation of any of the units tested. A nice touch is the matching aluminium external 240V adaptor included with both. The bigger Explorer performed well, keeping the fridge temperature to a maximum of about 7ûC. The freezer section performed excellently, maintaining a peak temperature of between -8ûC and -6ûC. In hindsight, the freezer thermostat could have been set a bit cooler. Total current draw was good compared with its category, with overall consumption less than an amp greater than the 14L-smaller DC-56.
Total capacity: 70L
Fridge capacity: 45L
Freezer capacity: 25L
Construction: Marine aluminium exterior, fibreglass interior
Insulation: 75mm polyurethane foam
Dimensions [L x W x H]: 820 x 500 x 540mm
Weight: 25kg
Input power: 12V (separate 240V inverter included)
Compressor: Danfoss BD-35
Manufactured in: Australia
Warranty: 3 years on cabinet, 1 year on compressor and controller
RRP: $1995 |
|
REEFER DT50
Unlike all the other brands tested here (which use 12V compressors), the Reefers use high-powered 240V compressors with an internal inverter upping the voltage from your fourby’s 12V electrical system. Accordingly, they demand a large amount of current in order to function correctly, which is why Refrigeration Research supplies them with a heavy-gauge wiring kit that draws power directly from the battery. It also explains why both power leads are hard-wired to the unit - to minimise voltage drop. In a novel touch, the small freezer section is sealed off with a steel plate that slots into place. The fridge section worked extremely well throughout the test, never climbing above 6ûC. The unit was preset to oscillate within 5ûC of the programmed minimum, which is precisely what it did. The freezer section was less impressive, with a temperature variation of as much as 25ûC. Current draw was the highest overall, consuming a total of 95A over the 24-hour period. This has to be viewed in light of how much more powerful its compressor is than the 12V fridges, meaning it still had plenty in reserve.
Refrigeration Research
Tel (08) 8398 3224
Fax (08) 8391 3030
www.refrigerationresearch.com.au
Total capacity: 50L
Fridge capacity: 40L
Freezer capacity: 10L
Construction: Steel cabinet
Insulation: 55mm high-density urethane
Dimensions [L x W x H]: 600 x 500 x 460mm
Weight: 25kg
Input power: 12V, 240V
Compressor: Mitsubishi
Manufactured in: Australia
Warranty: 3 years
RRP: $1900
|
|
REEFER ST70
The ST70 was the biggest capacity single-zone unit tested, though it is also available in dual-zone form. As with the DT50, this unit is controlled via a remote unit that plugs into a phone jack on the cabinet’s side. It allows you to set the temperature (obviously), but also how aggressively it maintains it (both were set to a tolerance of 5ûC), and the minimum battery voltage it will operate on. The lids on both Reefers use suction seals to hold them shut (like a domestic fridge), but latches are available on request. Given the DT50’s consistent performance and that the two use identical internals, we have to assume there was a fault with the ST70. Looking at the current data, as the temperature rose the compressor started to ‘fibrillate’ - running, but drawing only an amp, rather than its normal 7-8A. This accounts for why the temperature climbed so high, while the energy consumption was so much lower than the DT50’s. We’ll let you know what Refrigeration Research has to say once it has had a chance to examine the unit.
Total capacity: 70L
Fridge capacity: 70L
Freezer capacity: N/A
Construction: Steel cabinet
Insulation: 55mm high-density urethane
Dimensions [L x W x H]: 600 x 500 x 585mm
Weight: 30kg Input power: 12V, 240V
Compressor: Mitsubishi
Manufactured in: Australia
Warranty: 3 years RRP: $1910 |
|
VITRIFRIGO C41
Manufactured in Italy, the C41 was one of the smaller units tested. Externally, it loosely resembles the smaller Waeco with its roto-moulded plastic exterior. Bizarrely, the unit doesn’t have any handles at all, so you basically have to bear hug it to carry it around. It has two threaded points on its base that can be used to bolt in mounting brackets, though no mounting hardware is included with the unit. There’s also no plug on the end of the hard-wired 12V lead - just bare wires. The control panel is basic, consisting of an on/off button and five LEDs indicating what the thermostat is set at. Test performance was good. The unit cycled throughout the test but never lost its cool. Energy consumption was on par with other units in its size category.
Camec
Tel (07) 3710 9000
www.camec.com.au
C41
Total capacity: 41L
Fridge capacity: 41L
Freezer capacity: N/A
Construction: Roto-moulded polyethylene
Insulation: 40mm polyurethane
Dimensions [L x W x H]: 510 x 385 x 400mm
Weight: 18kg
Input power: 12-24V
Compressor: Danfoss BD-35
Assembled in: Italy
Warranty: 1 year
RRP: $1082 |
|
VITRIFRIGO C65
A medium-sized single-zone, the C65 has proper handles (unlike its little bro), though they do rotate through 180û, which means squashed fingers. The lid only seals with a spring-loaded clip, rather than a proper latch, though this is only likely to cause problems if you invert the fridge (roll your vehicle). Unlike the C41, the C65 has a removable plug, though there’s no 12V connector on the end (just bare wires). In the test, the C65 was almost a carbon copy of the C41. You’ll note its cycling rate was slightly slower due to the greater air capacity inside taking longer to warm up. Energy consumption at 55ûC was equal to the slightly smaller (but dual-zone) Explorer DC-56.
Total capacity: 65L
Fridge capacity: 65L
Freezer capacity: N/A
Construction: Roto-moulded polyethylene
Insulation: 50mm polyurethane Dimensions [L x W x H]: 720 x 475 x 450mm
Weight: 24kg
Input power: 12-24V
Compressor: Danfoss BD-35
Assembled in: Italy
Warranty: 1 year
RRP: $1233 |
|
WAECO CF-40
The CF-40 is the cheapest unit on test, and while it is obviously aimed at a more recreational market than the Explorer and Reefer ranges, it still appears to be a quality unit and sports a few nice features. For example, these include the internal light, sturdy handles and high-power ‘Turbo’ button, which maximises cooling performance. This particular model has a 240V socket built in. Like the CF-80, this fridge is at the cheaper end of the field, and you can see a few places where the manufacturer has saved on cost, such as the narrow piping on the lid and the plastic lid stay that holds it open. The little Waeco ran like clockwork, keeping its maximum internal temperature within about a degree throughout the entire 24-hour period. It also had the lowest energy consumption figures of the entire field, suggesting that even though it is sharply priced, it is still constructed with very effective insulation.
Tel (07) 5507 6000
Fax (07) 5507 6001
www.waeco.com.au
CF-40 AC
Total capacity: 40L
Fridge capacity: 40L
Freezer capacity: N/A
Construction: Steel with polypropylene trim
Insulation: 50mm polyurethane foam
Dimensions [L x W x H]: 710 x 360 x 580mm (with handles)
Weight: 16.8kg
Compressor: Danfoss BD-35F
Input power: 12V-24V, 240V
Assembled in: China
Warranty: 5 years for compressor, 3 years otherwise
RRP: $899 |
|
WAECO CF-80
The CF-80 features a removable fridge-freezer divider, allowing you to use it as one big fridge, if so desired. The unit functions on a sort of ‘spill over’ principle, where only the freezer section is actually cooled, with cold air flowing through into the fridge section. It also sports a separate dairy section for stuff you want to keep cool but not cold. Fridge performance was generally good, though a temperature range of nearly 8ûC suggests the Waeco’s cooling method is less effective than having a separate heat exchanger in the fridge compartment. That also accounts for why the graph displays a smooth line, rather than the zigzagging line that results when the zone is being directly cooled. Freezer performance was not quite as steady as the EvaKool units but always kept the temperature below -12ûC, thus fulfilling its job of keeping stuff frozen. Power consumption was second highest, drawing an average of 4A at 55ûC and a total of 62A over the 24-hour period.
Total capacity: 80L (76L with dividers)
Fridge capacity: 42L
Freezer capacity: 27L
Dairy capacity: 7L
Construction: Steel with polypropylene trim
Insulation: 50mm polyurethane foam
Dimensions [L x W x H]: 940 x 503 x 454mm (with handles)
Weight: 23kg
Input power: 12V-24V
Compressor: Danfoss BD-50F
Assembled in: China
Warranty: 5 years for compressor, 3 years otherwise
RRP: $1299 |
|
GENERAL RESULTS
With the exception of the ARB/Engel and Reefer units, all the fridges tested used Danfoss compressors. To wit, the Bushman, EvaKool RF47-DT, Explorer DC-56 and DC-70, Vitrifrigo C41 and C65, and Waeco CF-40 all use a BD-35 compressor. The EvaKool RF85-DT and Waeco CF-80 are powered by the larger BD-50 compressor. This means that differences in performance and power consumption between units with identical compressors will be partially due to the internal size of the cabinet. However, it will also give an indication of things like how well sealed and insulated the cabinet is, and how efficient the unit’s heat-exchange plates are.
Aside from the Reefer DT50, which appeared to be malfunctioning, all the units performed as expected. They coped with what was, frankly, a demanding test (can you imagine being locked in a room for four hours at 55ûC?). If, in the real world, the temperature started getting a little high, you could always turn the thermostat further down to compensate, and in the case of the EvaKool, Explorer and Waeco fridges, you can switch them onto a high-power mode. Power consumption figures were pretty impressive, too. Dual-zone fridges were clearly more power hungry than single-zone units, so it is important to consider whether you really need that separate freezer compartment or not. In the case of the smaller fridges, you could comfortably get 2-3 days of running from a N70-sized deep-cycle battery, while even the bigger dual-zone fridges should run for well over a day without recharging.
You will have no doubt noticed that there’s quite a disparity in price between the cheaper units and the more expensive ones. This reflects the sort of life that the manufacturer anticipates the fridge having. With the more expensive fridges, you’re paying for thicker insulation, stronger construction and heavier-duty components, which pay off if you’re planning on really giving them a flogging or running them for extended periods. Among the smaller fridges, we were particularly impressed with the Waeco CF-40. It was the cheapest unit tested but still had it where it counted, producing a temperature graph that could have been sketched by a metronome and consumed a measly 22.5A over the full 24 hours. It was harder to pick a standout unit from the larger fridges, because they were all very good, but ultimately we settled on the Explorer DC-70 for a couple of reasons.
We liked its aluminium-fibreglass construction, switchable high/low power settings, completely separate fridge/freezer compartments, separate thermostats for each compartment (which means you can turn one off if not required, saving power) and separate 240V adaptor (saving weight while using the unit in vehicle). We were similarly impressed with its testing performance and that it used the least juice among the large dual-zone units.
CONCLUSION
As we said right at the top, this isn’t a win/lose comparison. What fridge is best for you really depends on how much you have to spend and how you plan on using it. If you’re going to use it mainly over weekends or for a couple of days, then a compact single-zone fridge should neatly fit the bill so long as you pack the frozen stuff at the bottom. For longer trips, you’ll want the extra space and convenience of dual zones, but be aware that it comes at the cost of increased power consumption, so you may find you need to invest in a dual-battery system. The high-end units really come into their own over extended periods in harsh climates with a few million corrugations thrown in. But the most important thing is that whichever unit you choose, you can rest assured you’ll have a frosty one waiting for you at the end of the day.
|
|
