I recently tested how long a 12V 100Ah LiFePO4 battery will run a 12V RV fridge.
My 12V RV fridge ran for 102.5 hours off my 12V 100Ah LiFePO4 battery. Crazy!
Of course, your mileage will vary based on factors like ambient temperature, your fridge’s power usage, and how often you open it.
Based on my test, I’d say that, in most cases, a portable 12V RV fridge will run for around 70-100 hours on a 12V 100Ah LiFePO4 battery.
If you’re using a 12V 100Ah lead acid battery, you can expect the fridge to run for about 30-50 hours because lead acid batteries can only be discharged to 50%.
Keep reading for my full test results.
Video: 12V 100Ah LiFePO4 Battery vs 12V RV Fridge
Here’s a video I made of my runtime test. Check it out, and subscribe to my YouTube channel if you like these sorts of videos!
How Long Will a 100Ah Battery Run a 12V Fridge?
To answer this question, I connected my BougeRV 12V 30 Quart Portable Fridge to a Chins 12V 100Ah LiFePO4 Battery. I also connected a Victron BMV-712 Battery Monitor to the battery to monitor its state of charge and other specs in real time.
With my testing setup all ready to go, I turned the fridge on and started a timer.
With that, the test was underway.
Note: The battery monitor consumes a modest amount of power, but not enough to materially affect our results.
Because I wanted this test to reflect real-world usage, I added some food to the fridge. Throughout the test I’d open the fridge to grab food from it about as often as I would when using the fridge on a car camping trip.
After around 15 minutes, the battery was sitting at 99%.
The fridge was using about 50 watts and had consumed 1 amp hour.
Note: You may have noticed in the above photo that the battery monitor gives an estimate of time remaining. This estimate is based on the power draw from the battery in that moment. However, a fridge’s power usage is constantly fluctuating. Because of this, as you’ll see, the estimate given in the above photo is very inaccurate.
At 3 hours in, the battery was at 95%.
I used an infrared camera to check the temperature of the battery and fridge. The battery hadn’t heated up at all.
The fridge was hot where the compressor is — which is to be expected — and was cooling all the food down nicely on the inside.
At 12 hours in, the battery was at 84%.
The next day, I checked the fridge’s temperature and it was sitting at the temperature I’d set it to. My food was starting to freeze a bit, though, so I bumped up the temperature a few degrees to 37°F (3°C).
Soon after I started work for the day, the timer passed the 24-hour mark. The battery was sitting at 73%.
Like I mentioned, the fridge wasn’t actively cooling all of the time. It was going through cooling cycles where it would use up to 50 watts, and then what I’ll call “insulating” cycles where the power usage dropped to effectively zero watts.
At 36 hours in to the test the battery was still at 60%…how long is it gonna last??
On day 3 the timer passed the 48-hour mark, and the battery was sitting at 49%.
I checked the battery once more with my infrared camera. The battery was still as cool as the other side of the pillow.
Lead acid batteries can only be discharged to 50%. So, if you’re using a 12V 100Ah lead acid battery to run your 12V fridge, you’d be done at around this point. Your battery would be able to run your fridge for about 2 days at most before needing to be recharged.
However, I’m using a lithium iron phosphate (LiFePO4) battery for this test. Most LiFePO4 batteries can be safely discharged all the way to 0%, so that’s what I planned to do.
Note: Some people will only discharge their LiFePO4 batteries to 80% depth of discharge (DoD) to maximize battery lifespan. However, current LiFePO4 battery models, even budget ones, are rated for around 2000 cycles at 100% DoD, which still works out to years of consistent battery use and 4-5 times more cycles than many lead acid batteries.
On day 4, the timer hit the 72-hour mark. The battery had been continuously powering the battery for 3 days straight and it was sitting at 27%.
As I got ready for bed, I was prepared for the battery to die in the middle of the night. But, to my surprise, it was still going when I woke up the next day.
At 96 hours into the test, the battery was sitting at 5%. We had officially entered the home stretch.
I couldn’t believe it as the timer crossed the 100-hour mark with 2% battery left. 100 hours! Had you asked me at the start of the test, I would’ve guessed the battery would last around 50 hours.
Finally, the battery voltage dropped low enough for the fridge to automatically shut off. At that point, the fridge entered low voltage cutoff as indicated by the “E1” error message on its screen in the photo below. This is a useful safety feature to prevent the fridge from draining the battery too low. I had set my fridge to its lowest voltage threshold to eek out as much battery capacity as possible.
So how long did the battery last?
102 hours and 35 minutes. Wow!
That works out 4¼ days. The fridge consumed around 1 amp hour per hour on average.
Note: Most likely, you’ll be using your fridge outside or in a vehicle with wider temperature swings than inside where I tested mine. So I expect my runtime results to be the upper limit of what’s possible with a 100Ah lithium battery.
Here’s the final screenshot from my battery monitor:
Note: You may have noticed that the fridge consumed 102 amp hours from my 100Ah battery. That’s because my battery was new, and new LiFePO4 batteries will often slightly outperform their rated capacity.
And here are some of the historical trends for the battery geeks out there:
6 Factors Affecting How Long a 12V Fridge Will Run on a Battery
I ran this test to get a general idea of how long a 12V fridge will run on a battery. But how long your 12V battery runs your 12V fridge will vary based on a number of factors.
- Battery capacity: Your battery’s capacity is one of the main factors in how long it will run a fridge. If you find your battery isn’t running your fridge as long as you’d like, one of your options is to buy a bigger battery, such as a 200Ah LiFePO4 battery, or buy an identical second battery and wire the two batteries in parallel.
- Battery type: Lead acid batteries have 50% usable capacity, while LiFePO4 batteries have 100% usable capacity. So a 100Ah lead acid battery can deliver 50 amp hours, while a 100Ah LiFePO4 battery can deliver 100 amp hours. Also, lead acid batteries discharge less efficiently than lithium batteries, especially at higher C-rates.
- Fridge power usage: Factors like the fridge’s size, efficiency, temperature setting, and whether or not it has a freezer compartment all affect how many watts your fridge consumes on average. The more power it uses, the quicker it will drain your battery.
- Ambient temperature: The hotter it is, the harder a fridge has to work to keep the food inside it cool. I did my test inside where it generally stayed around room temperature. But, if you’re keeping your fridge in a car while car camping or in a van or RV with wider temperature swings, the outside temperature will play a large role in how long your battery lasts.
- How often you open the fridge: Cold air spills out every time you open your fridge, so the more you open it the quicker your battery will drain. With that being said, chest-style 12V fridges like the BougeRV 30 Quart Portable Fridge I used are well-designed in this regard. Because cold air sinks, it’s more likely to stay in a chest-style fridge which opens from the top rather than standard fridges which opens on the side.
- Voltage cutoff setting: Most 12V RV fridges monitor the inbound DC voltage from the battery and will turn off once the voltage drops below a certain threshold. You can usually adjust the threshold to a low, medium, or high voltage setting. A battery’s voltage drops as it discharges, so the higher you set your voltage cutoff threshold the less battery capacity your fridge will use before shutting off. This is a useful battery protection feature, especially for lead acid batteries that don’t have BMS’s. Consult our LiFePO4 battery and lead acid battery voltage charts for a general sense of the relation between voltage and state of charge for these different battery types.
What Size Battery Do I Need to Run a 12V Fridge?
Based on my results, I’d recommend a 12V 100Ah LiFePO4 battery (or a 12V 200Ah lead acid battery) if you want to run your fridge off a battery for 3-4 days.
If you only need to run your 12V fridge for 1-2 days, consider a 12V 50Ah LiFePO4 battery or a 12V 100Ah lead acid battery.
Be open to expanding your battery bank later on if the battery doesn’t last as long as you’d like. And, of course, these recommendations are assuming that the fridge is the only thing you’re powering off the battery. If you’re powering other 12V devices off the same battery, ideal battery size depends heavily on how much power the other devices are using.
A 100Ah battery could be all you need to run your fridge nonstop. With a properly sized solar power system, solar panels would charge the battery enough each day that your battery would never die.
If that interests you, check out my tutorial on how to solar power a 12V fridge. Solar powering your fridge really expands your options when it comes to long-term car camping and boondocking.
8 Ways to Increase How Long Your Battery Will Run Your Fridge
- Set the fridge to eco or low-power mode. Some 12V car fridges have an eco or energy-saving mode that uses less power. Typically, this means the fridge cools down slower than in the normal mode.
- Raise the fridge’s temperature. Experiment with higher temperatures, such as 37-40°F (3-4°C). The warmer you go, the less power the fridge will use.
- Buy an insulated fridge cover. Some brands sell compatible insulated covers for their fridges that reduce power usage by improving insulation.
- Buy sunshades for your vehicle. Keep the heat out of your vehicle to begin with by putting sunshades on your windows.
- Lower the fridge’s voltage cutoff (if using lithium batteries). Exercise caution when using this method. For lead acid batteries, I wouldn’t recommend lowering the cutoff voltage. If you consistently drain a lead acid battery lower than 50%, you can greatly shorten its lifespan. If using lithium batteries, lowering the cutoff voltage will let you use more of the battery’s capacity. It’s important to know that many LiFePO4 batteries enter a sleep mode (also called low voltage cutoff) when drained too low to protect the battery’s cells from overdischarge. If your battery enters sleep mode, it needs to be woken up again in order for it to be recharged.
- Open the fridge less. Be mindful of how often you’re opening it and how long you’re leaving it open for. Move common foods that don’t need to be refrigerated, such as tomatoes and hot sauce, to the pantry.
- Keep it inside and out of the sun. Move the fridge inside your vehicle if it’s cooler than outside. If you do need to use the fridge outside, such as when cooking at camp, keep it in the shade.
- Expand your battery bank. This is the most expensive option, but the most effective. You can swap your battery for a bigger one or buy an identical battery and wire it in parallel to double your battery bank’s amp hour capacity.
The Bottom Line
When I timed how long my 12V 100Ah LiFePO4 battery ran my 12V fridge, it lasted for 102.5 hours. That’s about 4¼ days.
Based on my results, a 12V 100Ah LiFePO4 battery will run a 12V RV fridge for 3-4 days. Because lead acid batteries have 50% usable capacity, a 12V 100Ah lead acid battery will run a 12V RV fridge for 1-2 days.
However, there are a lot of factors that will affect how long your battery lasts beyond just battery size — such as your fridge’s power usage and the ambient temperature. So take these numbers with a grain of salt.
If your battery isn’t lasting as long as you’d like, trying reducing your fridge’s power usage by increasing its temperature or buying a compatible insulated cover. As a last resort, you can always increase runtime by increasing your battery bank’s capacity.