PROCESS, METHOD AND MADNESS
Eight fridges, thousands of high-tech recordings and a wild card to ruffle a few feathers – it’s the ultimate fridge test.
WE’VE gathered eight of the most common 12-volt fridges on the market in an attempt to find out which one reigns supreme. We’ve also thrown in a wild card – a fridge purchased by the author back in 1990 – to see how advanced the latest and greatest units really are. The 26-year-old Engel has kept things cool on a trip around Australia, served as a ‘house’ freezer in Darwin, and it has since been used (and somewhat abused) on countless long and short-term camping trips.
Will our well-travelled and much-used Engel – complete with dents, rust and a dust-clogged compressor – be able to match it with the latest offerings?
To add a bucket-load of validity to our testing, we’ve sourced a few high-tech gadgets to prove a few impossible-toguess qualities of each fridge. We’ve programmed temperature data recorders to store readings every 10 minutes, which can then be graphed and overlaid with all other fridges, as well as ambient temperature recordings. We also hooked up high-precision power analysers to keep track of power usage, so we can regurgitate average amp-hours used by each fridge.
WE wanted to replicate a real camping environment, but there are some things you can’t control in the bush. So we opted to conduct the test in my non-nataaccredited mancave, complete with heaters, lights and 240-volt power.
We didn’t run the fridges on 240V; instead we used a 50-amp Projecta IC5000 7-stage Intelli-charge battery charger set to constant power supply to keep a 125ah Century deep-cycle battery charged.
This ‘power supply’ mode administers a float charge to the battery, to ensure appropriate power levels are maintained when running appliances. Plus it doesn’t run the risk of overcharging the battery.
The fridges were all wired into that one battery, so they all had a comparable 12-volt supply without the worry of the battery going flat.
We sourced a temperature data recording kit to record internal temps of each fridge every 10 minutes, plus we used an extra recorder to record ambient temperatures every 10 minutes.
Each fridge was packed with equal amounts of food and drinks: a loaf of bread, a two-litre orange juice bottle, eight cans of drink, four apples, four oranges, one packet of chocolate biscuits and a bag of salad leaves. The fridges were packed about two-thirds full to make the fridges work harder – given air temperature is harder to regulate than solid (food and liquid) temperatures.
DAY ONE: We packed the food and drinks into each fridge, which had been set at 3°C and had been running for two days prior to loading. The only exception was the old Engel, which has a simple numbered dial that was set at 2.5 (given my prior experience using it). Time would tell what temperature that setting would return.
DAY TWO: Each fridge remained closed day and night to monitor the effectiveness of the compressors and the accuracy of the temperature settings during a moderately warm day and cold night. This gave us the opportunity to graph the cool-down periods and establish how stable each fridge would operate without overcooling or overwarming the contents.
DAYS THREE AND FOUR: At midday each fridge door was opened for five minutes. We then turned blow heaters on in the shed (not pointing at the fridges) to raise the ambient temperatures, as we wanted to have a go at replicating the heat-sapping temperatures of a scorching Aussie summer. That finalised 100 hours of run-time over four and a bit days.
To test the thermal insulation properties of each fridge at the end of day four, we turned all the fridges off, left all the food inside and left the lids closed to record how long each fridge would hold a decent temperature. This final test replicated a battery going flat and how long you have until food starts to perish.
DAY FIVE: After turning all fridges off we waited for 24 hours to retrieve the
temperature data recorders. To keep it all even, no lids were opened and no fridges were touched.
We did measure instantaneous current draw, but it’s pretty much useless info so there was no point printing it. Some fridges draw a higher initial current than others, but cycle on for shorter periods of time compared to some with lower instant recordings that run for a longer period or cycle more often. Longterm power use is more important but is infinitely variable due to many factors. Again, all was even, so this gives you an ideal base line to compare all fridges.
When studying the graphs and collated data we concentrated on how well each fridge kept its internal cabinet temperature compared to the ambient temps, as well as how much power was consumed over the first 100 hours. That, combined with the final 24-hour power down – as well as the design, manufacturing finish and price – all led to our final decision.
All fridges were wired into a 125ah Century deep-cycle battery, kept topped up with a Projecta charger (right).