UPS for a Fridge: What Actually Works in an Australian Home
Yes, a UPS can run a refrigerator, and on a decent one you will get somewhere between 12 and 27 hours. But the UPS sitting under your desk will give you about 50 minutes, and most of the results you will find searching this are built for vaccine fridges in medical clinics, not the one in your kitchen.
Here is what actually works in an Australian home, with real numbers off a measured fridge rather than figures off a box.
Can a UPS run a refrigerator?
It can, provided two things are true.
It has to handle the surge. A fridge compressor draws several times its running wattage for the moment it kicks in. A unit that can only just cover the running load will trip on startup, which is the most common way this goes wrong.
It has to have enough battery to matter. This is where most UPS units fall over, and it is worth understanding why before you spend anything.
Why a computer UPS won't do it
A desktop UPS, the APC Back-UPS sort of thing, is not designed to keep an appliance alive. It is designed to give you ninety seconds to save your work and shut down cleanly.
Take the APC Back-UPS BX750MI, a common consumer model. It is 750VA and 410W with a sealed lead-acid battery, and it is rated for roughly 64 to 80 minutes at a 40 watt load.
Scale that to a fridge. The test fridge here averages 55 watts across a full day with the compressor cycling, so you would get somewhere around 50 minutes. And that 410 watt continuous rating leaves almost nothing spare for the compressor surge, so there is a fair chance it never gets that far.
Fifty minutes is not backup. It is a pause.
There is a second problem people hit. Cheaper UPS units put out a stepped or simulated sine wave rather than a true one, and compressor motors do not love it. A modern fridge with electronic controls may run hot, buzz, or refuse the supply entirely.
What size UPS do I need for a refrigerator?
Two numbers: enough output to start the compressor, and enough stored energy to last as long as your outages do.
For output, 1,000W continuous is comfortable for a domestic fridge and 1,800W is generous. What matters more is surge headroom, so look for a unit quoting a surge figure roughly double its continuous rating.
For capacity, do not guess. Your fridge already carries the number you need, and you can read it off in a minute. Every fridge sold here has an Energy Rating Label, and the figure in the energy consumption box is an estimate of how much electricity that model uses annually, in kilowatt hours.
- Take the annual kWh off the sticker
- Multiply by 1,000, then divide by 8,760 hours in a year
- That is your average watts. Add about 15W for inverter overhead
- Divide that into the usable capacity of the unit, which is about 95 per cent of its rating
The test fridge reads 373 kWh a year, which works out to 42.6 watts average. Worth knowing: measured overnight, the real figure came in at 55 watts, about 29 per cent above the label. The label is a controlled test, your kitchen is not, so do your sum and then knock some off. The full overnight run is in the BLUETTI FridgePower review if you want to see how far the label drifted.
Three ways to keep a fridge running in a blackout
Runtimes below are on that test fridge at its measured 55 watts. Swap in your own figure if yours is different.
| Option | Runtime | Switchover | Always plugged in? |
| Computer UPS (410W class) | Around 50 minutes | Yes | Yes, lives under the desk |
| Portable power station, 864Wh | About 12 hours | Yes, 20ms | Only if you leave it there |
| Portable power station, 1,433Wh | About 19 hours | Pass-through, switchover not published | Only if you leave it there |
| Dedicated fridge UPS, 2,016Wh | About 27 hours | Yes, under 10ms | Yes, it never moves |
Here is the honest version, because a lot of write-ups get this wrong. Most of these will take over on their own. A decent portable power station has a UPS mode and switches in around 20 milliseconds, which is quick enough that a compressor never notices.
The real question is the last column. A portable only protects your fridge while it is actually sitting behind the fridge, plugged in and charged. The weekend it goes camping, or the afternoon it charges the tools in the shed, your fridge has no backup and nothing tells you. A dedicated fridge UPS does one job and never leaves.
So if you are disciplined and the unit genuinely stays put, a portable is better value per watt hour and it earns its keep the rest of the year. If it is going to wander, buy the thing that cannot.
UPS for a freezer: what changes
Less than you would think, and the maths is the same. Find the sticker, do the sum.
Two differences worth knowing. A freezer running at minus 15°C or below will hold food frozen for up to 48 hours with the door shut if it is full, or 24 hours if it is half full, so a freezer buys you a day or two for free before the backup even matters. A fridge gives you about two hours.
The other is where it lives. A lot of the freezers people want to protect are in a shed or a garage, and most of these units are rated IP20, which means indoor and dry. Check that before you buy, because a damp shed will kill it.
Battery backup for a refrigerator and freezer together
Very doable, and the sums add rather than multiply. Work out the average watts for each off their stickers, add them, add 15W of overhead, and divide into the usable capacity.
Two appliances at roughly 55 watts each plus overhead is about 125 watts, which turns your 27 hours of cover into about 12. If that is not enough, expansion batteries are the cleaner fix than buying a second unit. A FridgePower takes up to three BlueCell 200 packs for 8,064Wh total, which on a single fridge is about four and a half days.
One caution: both appliances have to be on the same circuit run to the unit, and you have to actually check the combined surge. Two compressors starting at once is the worst moment your backup will ever see.
What it costs to leave one running all year
This is the part nobody mentions, and it is the reason some of you should not buy one.
A fridge UPS is plugged in permanently, so it draws power permanently. Bluetti quotes 4 watts standby on the FridgePower, and 4 watts is what came up on test here, but other testers have reported 12 to 17 watts on their units.
On a full-size family fridge that is noise. On a bar fridge it is not. A bar fridge only pulls around 12 watts, so at 17 watts idle you would be spending more power keeping the backup awake than the fridge it is protecting actually uses. If the thing you want to protect is small, do not buy a fridge UPS. Get a small portable power station and accept that you have to plug it in yourself.
Which one should you buy?
Full-size fridge, and the backup needs to stay put: a dedicated fridge UPS. The BLUETTI FridgePower ran a family fridge for about 27 hours on test, with switchover under 10 milliseconds so the compressor never stutters. Read the review before you buy, because there is a default setting that will catch you out.
You are usually home, and you camp: a portable power station. Cheaper per watt hour, it has a UPS mode of its own, and it earns its keep the rest of your year. Check the surge rating covers your compressor, and be honest with yourself about whether it will still be plugged in behind the fridge in six months.
Bar fridge or drinks fridge: a small power station, and only if you actually care about what is in it.
Vaccine or medical fridge: not this article. Talk to a medical supplier, because those carry monitoring and compliance requirements a consumer unit will not meet.
Not sure which way to go? The Power Station Finder takes two minutes, or call 03 7056 6732 with your sticker figure in hand and we will do the sum with you. If the answer is that you do not need one, we will say so.
Worth reading next: the BLUETTI FridgePower review for the long version on the unit in that last row, how long food actually lasts in a fridge without power, and what size power station you need to run a fridge.
Runtime figures are calculated from a fridge measured at 55 watts average, with 15 watts allowed for inverter overhead and 95 per cent usable battery capacity. Your fridge will differ. Switchover times are from each manufacturer's published specification; where a figure is not published we have said so rather than assumed. Checked 2 September 2026. Some product photography supplied by Bluetti.
