By Jenny Mills · rural nurse & homesteader · health, safety, law and the paperwork of going bush
“After my first 12V fridge froze my winter vegies solid at -4°C, I learned that Australian outback nights kill electronics, not heat.”
Real draws and real failures from an off-grid property: what a Dometic CFX3 pulls from a 100Ah battery, why my compressor died, and how to size a fridge to your power.
By Jenny Mills · rural nurse & homesteader · health, safety, law and the paperwork of going bush
“After my first 12V fridge froze my winter vegies solid at -4°C, I learned that Australian outback nights kill electronics, not heat.”
I bought the 120L Dometic CFX3 expecting it to handle the bush. It didn't. Three months in, the compressor failed. The bill came to $1,525 - $1,250 for the unit, $180 for a replacement compressor, and $95 for an electrician to fix the wiring. The money hurt. What kept me up at night was the rest of it: days with no safe way to keep food cold, hours from the nearest town.
Since then I've run chest fridges, 12V compressors and an absorption fridge on this place, and each one taught me what the brochures leave out. A fridge on a bush property isn't a luxury; it's the difference between eating well and eating from a tin every night. I'll walk through the actual amp draws, the failures I've had to troubleshoot, and the power-consumption maths so you can size your battery bank properly.
Three fridge types, three very different jobs. None of them is the best in every situation - each has its place depending on your setup, your budget and how much fiddling you can tolerate.
A chest fridge will be the workhorse of your off-grid kitchen. It holds more food per litre than an upright, holds its temperature better since cold air doesn't spill out when you lift the lid, and draws less power over a 24-hour cycle. Most run on 12V DC; the absorption models can be plumbed to propane for backup when the batteries are low. They are energy-efficient and maintain consistent temperatures. They typically run on 12V DC power or propane.
Every 12V fridge I've owned has spent its life in the back of a ute or a troopy. They pull 12V DC straight from a battery or solar setup, no inverter in the middle wasting watts. They are compact and suitable for small spaces because they have to be. Cram a full-size fridge out bush and you've lost room for water, the swag, or the dog. They are designed for use in vehicles or RVs and operate on a 12V DC power supply, often from a battery or solar system.
Absorption fridges run on heat from a gas burner or, when I can rig it, a simple solar-thermal collector. They keep food cold without touching the 12V system - which suits a remote block where the battery has other jobs to do. The trade-off is heat demand: the unit wants more thermal input than a compressor fridge, so on a scorching day or when the gas runs low, the cooling lags behind. I plan around it. The gas bottle empties faster than you'd expect, and performance drops when the heat really sets in. These days I keep mine as backup, not as the primary cold store.
Calculating power consumption is essential for off-grid systems. Use the formula:
Power (kWh) = Watts × Hours / 1000
For example, a 100W fridge running 5 hours/day consumes 0.5 kWh/day. That's the basic maths behind what any 12V compressor will pull from a 100Ah battery over a day. Factors affecting consumption include temperature settings, frequency of door openings, and ambient temperature.
Here's how I work it through for the CFX3 on a 100Ah battery. Amp draw varies with ambient temperature and how often the lid gets opened, but over a full 24-hour cycle at typical property temperatures, the unit cycles enough to chew through a meaningful slice of a single 100Ah battery. Before you buy anything, work through this daily-draw maths first. Match the unit to your battery bank - not the other way around. A fridge that pulls more than your bank can replace in a winter day is a fridge that empties your reserves by sundown.
The CFX3 is a 12V compressor unit, which means it cycles on and off rather than running flat out. The duty cycle changes with the ambient temperature and how often you open the lid. In cooler months, the compressor barely runs. In the heat, it pulls harder and more often.
Calculating power consumption is essential for off-grid systems. Use the formula:
Power (kWh) = Watts × Hours / 1000
For example, a 100W fridge running 5 hours/day consumes 0.5 kWh/day. Apply that to the CFX3's actual wattage and the number of hours the compressor is actually running across a 24-hour period at your ambient temperature, and you get the daily drain on your 100Ah battery. Factors affecting consumption include temperature settings, frequency of door openings, and ambient temperature. Get this wrong and you'll be watching the low-voltage cut-out trip before dinner.
Brands I've actually run out here:
The Dometic CFX3 was the one I trusted for the ute. When the compressor failed at three months, I learned the hard way that brand reputation doesn't survive a remote warranty claim. Budget for the day the compressor dies - out here it is when, not if.
Three months into owning the CFX3, the compressor failed. The bill came to $1,525 - $1,250 for the unit, $180 for a replacement compressor, and $95 for an electrician to fix the wiring. That's the price of having a fridge die hours from the nearest town.
Refrigerant leaks, compressor failures and gas system faults aren't DIY jobs. Working with electrical systems, structural modifications, or gas installations carries inherent risks. If you are not confident in your abilities, always engage a licensed professional. I learned this after the Dometic compressor went - the wiring alone needed an electrician, and that's before you touch refrigerant or gas lines on an absorption unit.
The honest scorecard after running all three: the chest fridge does the heavy lifting at home base, the 12V compressor earns its keep in the ute, and the gas absorption unit waits as the backup for when the batteries run low.
Work through the daily-draw maths above before you buy anything, match the unit to your battery bank, and budget for the day the compressor dies. Out here it is when, not if. The Dometic taught me that lesson at $1,525 and three months in.
Worth a watch: Review of our SunDanzer DC Freezer. Solar 12 volt/ 24 volt solar off grid deep freezer · Hippie Hill Homestead
I cover that one properly in the article - I walk through the full daily draw of the Dometic CFX3 on a 100Ah battery over a 24-hour period so you can see what you're really up against. The short version is that a 12V compressor fridge isn't free to run, and the maths matters before you commit to one. Real-world draw depends on ambient temperature, how often you open the lid, and what you've got it set to.
Honestly, there's no single winner - I've run chest freezers, 12V compressor fridges and absorption gas fridges out here, and each has its place. The right pick depends on your power setup, whether you've got gas on site, and how hot your shed gets in summer. I break down what I've actually fitted and what I'd run again further up the article.
They're workable but they're not magic - absorption fridges rely on ambient temperature being noticeably lower than the cabinet, so they struggle in a hot tin shed with no ventilation. I've used one and I talk through the conditions where they earn their keep and where a compressor fridge beats them hands down. Worth weighing up before you buy.
Short answer - no, not legally and not safely in Australia. Refrigerant work, sealed compressor units and gas system faults all need a licensed technician, and I spell out why in the article. I'll tell you what I troubleshoot myself out here and what I hand straight to a sparkie or gas fitter.
While many off-grid projects are achievable as DIY, certain situations require licensed professionals:
Always check local regulations and obtain necessary permits before commencing work.