Sometimes, cooling down can require cranking the heat – and when it comes to staying fresh alfresco, the 12V fridge is as power-hungry as it is popular! They’re the ultimate comfort in camping. Menus can expand to include pretty much anything you can cook at home, as long as you can fit it in the fridge! These days, portable fridges are extremely popular additions to any camping and 4WD arrangement – and if you head out regularly, they become well and truly worth the expense.
However, a fridge requires a fair bit of energy to run – it’s almost always the highest consumer, and you need to get that power from somewhere. There is a lot of focus on solar panels and batteries, but there are a number of ways you can reduce the energy consumption from your 12V fridge.
In this blog, we defrost our top 10 tips for how to reduce the energy consumption of your 12V fridge off the grid – so you can keep the cans cold and perishables fresh for longer. From kicking back on the boat to basking in the balmy bliss of the campsite, read on for a refresher on fridge maintenance facts and energy-saving hacks to keep the tucker in date.
These days, portable fridges are extremely popular additions to any camping and 4WD arrangement. Image: Dometic
How Much Power Does a Fridge Need?
There are many different factors that affect the energy consumption of a 12V fridge: size, compressor style, ambient temperature, insulation thickness, the temperature they are set to cool to, what you are using it for – the list goes on. However, most will consume in between 1 amp and 6 amps (with 2.5 amps being fairly average) per hour when running. That said, a fridge won’t usually run 100% of the time, so it only pulls that current when the compressor is on.
Most fridges are loud enough to hear within a few metres. Again, the cycle time varies considerably, but on average they run about 50% of the time.
Using the above example – where the fridge draws 2.5 amps when the compressor is on, but only runs for 1/2 the day – it will use 30 amp hours of the battery capacity.
Measuring a Fridge’s Power Consumption
Power consumption is measured in Amps per Hour (Aph or a/h), which refers to the number of amps an appliance uses in one hour of use.
There are 2 ways that a/h is measured for camping fridges:
- Usage draw – this is the amount of power the fridge draws while running
- Average draw – this is the amount of power the fridge draws per hour over a 24-hour period
When determining power consumption, it is important to look at both figures. However, the second figure (average draw), will give the best indication of fridge efficiency.
Fridges will cycle on and off to maintain temperature. Better insulation means less cycling, in turn resulting in a better average current draw.
Do not run your fridge off your main battery. Run a dual battery setup instead. Image: Aaron Schubert
What Battery Should a Fridge Run Off?
Fridges should never run off the cranking battery that you use to start your vehicle. The only exception to this is while you are driving, and only if you absolutely must. The reason behind this is simple: your cranking battery is imperative to start your vehicle, so if you run it flat you’ll be in serious trouble.
The most common way to run a fridge is with a second battery, which is isolated from the main cranking battery. The best option is a deep-cycle battery, designed (as the name suggests) to cycle from full to half empty, and back again – anywhere from 1200-1700 times. You can run them off a normal cranking battery, though they don’t like to be cycled and you will shorten its life substantially. Lithium batteries are also becoming more popular, as they have several advantages, but they also come at a pretty hefty cost.
How Low Can I Go With the Battery?
Far too many people think that just because their fridge is running, the battery has enough power left. This is not the case – you should not run your battery to below 50% of charge (normally around 12.2-12.3 volts).
A fridge will continue to run well below this until the low-level alarm is set off and cuts the power. Most fridges have a low-level cut-out, but it’s not usually until well under 12 volts. If you run your battery below 50% of charge, its lifespan will be rapidly decreased – and batteries aren’t cheap!
If you have a 100Ah deep-cycle battery, you should only be using 50 amps of its capacity. This, in the above scenario, is only 1 and 2/3 of a day (without any other consumption) before you start to damage your battery.
From that point on, you either need to start your vehicle and allow the alternator to charge the battery, or arrange some solar input. However, after a couple of cloudy days things start to get a bit desperate! Using your vehicle’s engine to charge the battery is a pretty uneconomical way to do things too.
So – how can you reduce the energy consumption from your 12V fridge? Well, in a similar way to keeping ice cold for longer in an ice box, actually!
You should not run your battery to below 50% of charge. Image: Dometic
1. Cool Your Items Before Leaving Home
Most fridges will have the ability to run on 240V (this is a feature to look for when buying a fridge). If you can avoid it, don’t put room temperature items in your fridge. It will only have it working harder and using more power. Run the fridge on 240V and cool it down at home before heading off on your trip. Most power will be drawn while cooling down the interior of the fridge, so use 240V at home to lower temperature before putting the fridge on 12V.
Obviously, this is unavoidable if you are on the road. Where possible though, pre-chill your food and drink.
2. Crack the Lid Slowly
If you unlatch your fridge and yank the lid up, the rapid movement draws a huge volume of cold air out of your fridge and sends it into the atmosphere. Once you close the lid, the fridge needs to cool down the hot air you’ve just filled it with.
The trick is simple: crack the lid gently until it’s open about 10cm, then open it normally. This will both stop most of the cold air escaping, and save you some substantial power consumption.
Crack the lid gently until it’s open about 10cm, then open it normally. Image: Engel
3. Keep the Fridge Full
A full fridge works much more efficiently than an empty one. If you are running low on food and drinks in the fridge, bottles of water work very well. Once they are cool, you’ll save a lot of energy; they don’t immediately change temperature like air does when the lid is opened.
Make sure the food and drink you put into your camping fridge are already cold. If you put a warm slab of drinks into the fridge, it will use lots of power to cool those drinks down to temperature, before it starts cycling again.
Another recommendation is to allow your fridge to freeze (-15 degrees) and add a couple of freezer bricks. Make sure to put the fridge on a few days in advance for it to freeze properly. This will ensure the interior of your fridge is nice and cold. If you have enough space to fit your food in with the freezer bricks, leave one or two in when you pack your food before adjusting = the temperature of the fridge back to two degrees. The fridge will work like an Esky for the first part of your trip, and may not even turn itself on to keep cold for days!
4. Keep Your Fridge as Cool as Possible
It sounds like common sense, but many fridges have been seen laying around in the sun at campsites. Obviously, your fridge will work better in the shade, and out of hot vehicles. If it’s packed in the boot and your car is in the sun, your fridge will be combatting high ambient temperatures and will likely drain your battery twice as fast.
The difference between a fridge operating in an ambient temperature of 25 to 40 degrees is huge. The hotter the air outside of the fridge, the harder your compressor has to work. Obviously, you can’t always the ambient temperature, but you can control where your fridge is stored.
Parking under a tree, for example, will keep your vehicle much cooler and reduce how much work the fridge has to do to keep your food and drinks cold. If you are parked up, open the back of the vehicle so it doesn’t heat up.
A full fridge works much more efficiently than an empty one. Image: Dometic
A fridge slide is a good way of keeping your fridge secure in the 4WD, but popping it out like this, when you’re at camp, ensures airflow. Image: Aaron Schubert
5. Airflow is Imperative
The compressor in your fridge will produce heat, a by-product of reducing the temperature inside the cabinet. It’s important to allow plenty of space for this heat to escape from your fridge. More ventilation results in better efficiency. It’s all well and good having your fridge packed in tight – but if it can’t breathe freely, you are making it work hard. Ensure the compressor has ample room to suck in clean, cool air. If you have the fridge mounted in an enclosed area, consider the use of a small vent or computer fan to aid air circulation.
Toolboxes on the front of camper trailers are popular for mounting fridges, but on a warm day they can easily reach 65 degrees inside. While it probably won’t kill your fridge, it isn’t doing it any favours in terms of longevity – and will most certainly cause it to consume more power.
6. Fridge Covers
You’ll see that a lot of fridge manufacturers sell covers for their fridges. These help to protect the fridge, but also improve their insulation properties. The better insulated your fridge, the less heat that can pass through and the less cold air that can escape. Almost all fridges will benefit from an insulative cover by preventing the outer casing from heating up. It’s kind-of like putting an Esky into a soft cooler bag. By adding extra insulation to the fridge, it will stay colder for longer and thus use less power.
Next time you are at your fridge, touch the outside of it when it’s running. If it is noticeably cooler than the air around you, the insulation is allowing the cold to escape.
Fridge covers help insulate the fridge so that it runs cooler. Image: Aaron Schubert
7. Time and Number of Times Opened
The longer you leave your fridge open, the more it has to cool down when you close it again. Every time you open the fridge, you will displace the cold air. This means the fridge has to cool all the new air that has entered the fridge. Limit the amount of time the fridge is left open or how frequently it is opened to prevent the internal temperature rising. Make a habit of grabbing what you need quickly and closing the lid.
If you are about to cook something, have a think about what you need before opening the fridge. Don’t limit yourself to only opening the fridge a few times a day, but anything you can do to limit the number of times you open the fridge is ideal. As mentioned in the blog post on keeping ice from melting, perhaps have a small icebox at your disposal to keep drinks nearby. This will save you from having to open the fridge too often.
8. Close the Lid Properly
While it’s easy to just drop the lid and not do up the latches, if any air can pass in or out it’ll have the fridge working harder. Take the extra two seconds to latch it closed.
Snowys blogger Aaron Schubert’s trusty EvaKool 12V fridge. Image: Aaron Schubert.
9. Check the Wiring
The power supply to your fridge needs to have adequately sized wiring. If it is too small, you’ll lose efficiency quite quickly. Usually, this is an issue from your battery to the fridge power-point, especially if it’s running from the front of the vehicle to the rear. It’s recommended to run a 6mm square cable, minimum.
Heavy-duty wiring from your 12V battery to your fridge won’t have your fridge use any less power, but it will help you get more out of your battery. Many standard vehicle setups have thin wiring looms that attribute to voltage drop. This means that while your battery reads 12.5V, only 12V is reaching your fridge. Furthermore, if your fridge is fitted with battery protection, it may turn itself off despite there being plenty of life left in your battery.
10. Use a Quality Fridge
Lastly, if you’ve bought yourself a cheap fridge and you find it’s chewing the power, it might be time to consider upgrading to a more quality unit. Brands like Engel, Dometic, Evakool, and Bushman have each earned themselves a solid reputation!
Keep an eye on your voltage usage. Image: Aaron Schubert
Enjoy Your Fridge!
There’s nothing quite like being able to pull a cold drink from your fridge in the middle of nowhere. Enjoy the luxury, do what you can to conserve energy consumption – and if it’s still using too much, consider looking at improving your solar or battery arrangement.
There’s nothing quite like being able to pull a cold drink from your fridge in the middle of nowhere. Image: Dometic
This blog is a consolidation of a 2016 work by Aaron Schubert and a 2015 work by David Leslie, updated for 2024.
What sort of 12V fridge do you use? Let us know in the comments.
From setup tips and hiking trips, to campsite cooking and 4WD kits – our Snowys Bloggers boast exceptional outdoor, fitness, and travel experience. Combined, their individual content is only enhanced – and the result for the fellow outdoor enthusiasts following along is a bigger, beefier, and more beneficial blog.
These articles are an updated collaboration of previous or existing works on the Snowys Blog.
Hi, I have a 12v 120 liter refrigerator. I bought it new and it works all the time. It doesn’t go into a break. It can work 24 hours. What could be the problem? It should be noted that I was at the store where I bought it and they replaced the refrigerator with a new one and the new refrigerator also works the same. I would appreciate help. What could be the problem?
Bought one on special. Suposedly rated down to minus 18, but never got colder than minus 12, And worse would not even nearly retain the temperature overnight. (Was tunning it all day, in a house on a large solar-system, and switching it off for about eight hours overnight. On occasion it went from minus 12 to PLUS 8 degrees in that 8 hour period.
The shop took it back without a quibble, suggesting the efficiency failure was well-known..
The Engel I had for years was at least twice as effective, so I replaced it with another one.
Maintains ample coldness (via non-electronic thermostat) and is never less than minus 6 in the morning when it’s restarted. And runs @32 Watts at full power. (or about 80% of the Coolman. A couple of hundred dollars more expensive, but worth every penny of it. (My previous one lasted almost 15 years without a hitch, and STILL runs perfectly on 240vac.
Hey Trevor, thanks for sharing your experience. We agree that Engel is fantastic!
I’m wondering if you can only safely run your battery to 50% why does the waeco have medium 11.2v and low 10.1v
It’s not so much about safety but more about the longevity of the battery, Ken, you’ve raised a fair question though.
Ideally with wet cell and AGM batteries you don’t want to discharge them deeply i.e. beyond 50%, too often. I try and keep my voltage above 12V which is a very rough guide to keeping the state of charge above 50%. I don’t know why fridges have cut out voltages at such low levels, likely to ensure a battery has some charge left for emergency use if the fridge is let loose to use as much power as it wants. But if your battery drops to 10.1V you’ll probably need to replace it.
I’d recommend you set this cut out voltage as high as possible. The medium setting is a good emergency setting if you find yourself caught out on the odd occasion, but the highest cut out setting with a good system to keep the battery topped up is your best bet.
Hope that makes sense.
So the manufacturer of these portable fridges know they are not insulated properly, the retail outlets know they are not insulated properly but will still make and sell poorly insulated product and still charge a price that is ridiculous, considering that they know.
Not all fridges are made the same, mate! But, even with better brands, how a fridge is operated and stored will affect its efficiency. This blog post and this blog post talk about insulation in more detail and might help to restore your faith..? Cheers
I make ice with my Iceco Go12. I have some plastic containers which allow me to harvest 20 lbs of ice in 2 hours. I put the ice in my homemade “Yeti” (A cheap styrofoam cooler set inside another and all gaps stuffed with pink insulation. My ice lasts 4 days in the Tuscon area from Oct to Apr.) The Go12 is powered by a 100-watt Renogy Mono panel. (On sale as of 27 January 2021 on Amazon.ca for $130 Canadian and Prime free delivery.) The panel is connected directly to the fridge through a Buck connector–no battery.
Great article. Definitely agree you should avoid cheap fridges – we caught a $800 kings 90L fridge – it’s been a nightmare from the start, been in for “repairs” with no improvement. We know have two seperate high powered solar systems and two high capacity batteries just to get the fridge through short camping trips- if your going away for more than 4 days your wasting your time with kings 90L fridge – maybe a petrol generator will help .
All up the extra kit just to keep the fridge /freezer from retiring out every few hours could have been avoided if we just went with our original idea of buying a higher quality /more expensive fridge/freezer.
Michael, We run a Waeco 95litre dual zone off grid for weeks at a time just on battery and solar. We run 430 watts of portable solar panels and 280 AH of battery. The fridge draws, on average, 4.5 amps p/hr.
We do have a 2 Kva generator for extended overcast/rainy days. It doesn’t matter what size fridge you run it is how you power it and most fridges over long stay off grid will require a back up power source for bad weather.
Terrific insight, thanks Karen!
We have 50L and a 75L dual zone Brass Monkeys. Australian made and owned, german technology, 3 year warranty and half the price of the others.
Brass Monkey fridges are made in China
Thank you for the article and the tips. Cooling the fridge and filling with cold items/water bottles makes sense. What about as the trip winds down and the fridge is getting more empty. If you have no cold water bottles, is it still better to stick in whatever you have at room temperature vs have space?
Hey guys, having a little trouble running my 12V 40 ltr Engle fridge rear of my 200 series Toyota, the second battery is at 12.5 volts Idling 13.3 running, system was fitted by a reputable company, the battery is 8 months old and seems to be fine holding charge ok. What the F;#@ do I do ?
Hi Les.
Is the fridge running at all? It should operate from a battery at those voltages, especially with the engine running.
The voltages you mention do seem a little low to me though, my auxiliary is on the way out and sits at about 12.5V resting, up to 14V with the engine running. With proper maintenance, an auxiliary battery should last a few years, but improper care and use, for example running it below 50% charge, can decrease the life significantly.
If the fridge is not running at all in your car check it from a 240V outlet. If it runs from 240V then the problem is either with the car or the battery. If not, then depending on the age of your fridge you can follow up on warranty or repair.
Then check to make sure there is power to the auxiliary plug that you are running your fridge from. Plugin another accessory to see if it works.
If none of the above highlight anything obvious, I’d take your car back to the place that installed your system to have them troubleshoot for you, they should be able to test your battery for you also.
I hope that helps.
Decent post on reducing fridge power usage Aaron.
Coupla extra things tho.
1. choose the best possie for the fridge – tint the window nearby or install a curtain to reduce/eliminate sun shining through the vehicle window onto the fridge.
2. in some cooler climates it may be possible to turn the fridge off at night.
3. some fridges have an economy mode – use it, especially at night.
4.bulk up the fridges transit cover with flat polyurethane foam to add extra insulation. Some covers are a bit on the thin side. Careful not to allow sheet foam sheeting to move over the compressor vents.
5. any fridge over 60L will use big gobs of power, Think carefully about increasing your solar panels (if using them) to 300W or more and dual batteries over 120AH.
6. Still on big fridges, it can be worthwhile to use the biggie as a fridge only and buy a smaller fridge for your freezer. The smaller fridge need only to be opened maybe once a day. Frozen items to be used next meal are transferred to the fridge to thaw but also use the cold in those food items for the big fridge So win win there. It can work out cheaper power-wise in he long run but also much more convenient.
7. Similar to placing only cold food into your fridge at the start of your trip, get your fridge/s down to working temperature before heading out.
Same deal with your ice coolers.
Happy Camping!
Hi Philbo,
I’m planning to install a Dellonda 12v fridge freezer box under my raised bed.
I will build a box around it and was wondering about putting an insulating layer of such as cellotex around the box as extra insulation for the fridge. Do you think this would work?
Regarding Engel fridges mine is 40litre and emailed Engel to find out age which they told me exactly. The fridge is rubbish because it broke a $4.00 hinge after 22 years!! You can keep your plastic fridges??
We have just bought a 12 volt 12 litre ridge ryder thermo cooler fridge for travelling in our car interstate. Is this going to be OK to run it from the cigarette lighter in the car and turn off when we stop for brakes. The instructions say it uses 30 watts.
Any help would be appreciated. Thanks
Waeco CFX28. My reduce energy tip….I wanted to reduce the risk of hot exhaust air getting trapped under the insulation cover reducing the efficiency of he insulation cover, so some strips of Velcro from Bunnings came in handy.
Nice one Mark, sometimes you have to get crafty to come up with a good solution to a problem. Cheers!
Great article – thanks! One really valuable tip (from the Yeti coolers web site) that I use all the time is to put an already cold wet towel in the fridge on top of the food. This creates a barrier between the food and air on top and minimizes the cold air loss when you open the lid. Also, pack the fridge with the last day’s food at the bottom so you’re taking food from the top of the food pile and not digging down into the coldest part of the fridge until you have to.
Cheers
Those are both great tips – especially the one about putting the last day’s food at the bottom of the fridge. Thanks for sharing Dan 🙂
Great idea about using a wet towel on top of food in fridge cheerd
Hi Aron I use a Waeco 60 ltr best bit of kit i have ever purchased for camping got it from snowys looking at getting the 28 jyst for freezing cheers h a ppy camping
Glad to hear that you’re loving the Waeco fridge that you got from us, Angelo!
I run two fridges one , Waeco and a ARB and I’ve had no trouble with them the Waeco I’ve had since 2007.
Great to hear that your fridge is still performing well for more than a decade, Danny.
Just goes to show that it’s worth investing in quality gear that’ll last you for years to come.
Hi Aaron
Thanks for explaining the energy usage for fridges. Are you familiar with the Primus Portable Power Pack 44Ah? I am new to this technology and am wondering if the usage in Amps as discussed above equates to Ah? In other words, when you say that a fridge (I have a Waeco EFX35) will run about 36 hours on a 100 Amp battery that mine will be less than half that? I actually just checked the voltage now and it was down to 12.0. However, as soon as I hooked it up to solar panels the voltage jumped to 12.6. Is that normal? Makes me question though which reading is correct…
The instructions also indicates that I can charge my laptop using this Power Pack, however I thought a pure sinewave inverter was required for this. Are you able to advise on this as well?
Grateful for any insight you are able to provide… 🙂
Hey Emmy,
I am not familiar with the Primus power pack, but if it is 44 amp hour, then you will basically have 22 amp hours that you can safely use from maximum charge without reducing the lifespan of the battery.
Your fridge will run from this for a little amount of time, but its not really suitablly matched. Remember the 36 hours is a guide that will change with a lot of different factors; how much you have in the fridge, how often you open it, what temperature its set to, what the outside temperature is, how much air flow it has etc etc. I’d say you’d be pushing to get more than 10 hours out of it safely, which is a problem.
When you add the solar panels it will jump, but if you remove them the the volts will go back down; same as if you had it on a battery charger. 12.05 volts is roughly 50% used on your batteries, so you shouldn’t let it drop below that if possible.
As for the laptop, if you are running it off the powerpack a pure sinewave inverter is much safer. If you don’t value the laptop too much they will run off a standard inverter, but there is a risk of damaging the laptop.
I believe that if you remove the battery and charge it off the laptop it should be fine, but it would pay to double check that!
Best of luck!
Aaron
Good advice but lots of terminology errors in the article
Amps measures current not power but for a fixed voltage will be proportional to power consumption
Amp hours measures battery capacity – it should read 100 amp hour deep cycle battery not 100 amp
Amps drawn will be proportional to but not the same as power consumption (which is measured in watts)
Amp hours will be proprtional to but not the same as energy consumption (which is measured in kilowatt hours)
I would reword the following…
“Using the above example of 2.5Amps an hour, on 50% of the time, a fridge will use around 30Amps of power every 24 hours.”
to…
Using thew above example where the fridge draws 2.5 amps when the compressor is on but only runs for 1/2 the day it will use 30 amp hours of the battery capacity.”
Hey Andrew,
Thanks for the comment mate. You are correct with what you’ve said; I was just trying to keep it as simple and easy to understand for those new to the 12V side of things. I’m happy to have that section re-worded though!
Aaron
Hi Andrew, youseem to know what you are talking about so I was hoping I could ask you a question. I have a new Waeco 35 litre car fridge and a new Roman deep cell battery. I have fully charged the battery and it will run the fridge for about 12 hours or until the digital display says it is on 12.6 volts then the current stops and the fridge stops working. Do you think it is the fridge with an internal switch that does this or is the battery not able to support the fridge after 12 hours which I think is quite a short time for a battery that cost 359 dollars. When the battery is fully charged the digital display says 14.6. I hope you dont mind me asking such a menial question. Thanks and regards.
I’m not sure if our system notifies other commenters if there’s a reply, so in case Andrew doesn’t jump in Jo – feel free to give our customer service team a buzz on 1300 914 007 and one of our fridge experts can try and troubleshoot the issue for you over the phone – cheers Jo!