While the question “How many batteries do I need for my refrigerator?” lacks a one-size-fits-all answer, sizing a battery bank for your refrigerator is a straightforward process when you consider the following factors:
- The energy consumption of your refrigerator.
- The desired duration for which the battery bank should be able to power your refrigerator.
- The type of batteries you intend to use and their recommended Depth Of Discharge (DOD).
In this article, I will kick things off by providing estimated battery capacity requirements for various refrigerator types and sizes, offering you a helpful benchmark.
After that, I’ll accompany you through a step-by-step calculation process that will uncover the ideal battery capacity tailored to your unique refrigerator requirements.
Once we have that covered, it’s important to address the fact that most refrigerators rely on AC (Alternating Current) power. Consequently, it becomes crucial to discuss a key component that may be necessary to power your fridge: an inverter.
Let’s dive in.
I get commissions for purchases made through links in this post.
How many batteries to run a refrigerator?
To run a refrigerator on batteries for a 24-hour period, you’ll typically need 50Ah to 400Ah (Amp-hours) of battery capacity at 12 Volts. This translates to 1-8 batteries rated at 12V – 50Ah, or 1-4 batteries rated at 12V – 100Ah.
The exact size of the battery bank that you would need will depend on the size of the refrigerator and the amount of energy that it consumes.
For example, while a 12-volt fridge (1.6-2.5 Cu. ft.) will typically require around 50 Ah of battery capacity, a larger residential refrigerator (18-25 Cu. ft.) may need up to 400Ah.
Additionally, the battery bank’s size will also be influenced by the type of batteries you intend on using and their recommended Depth Of Discharge (DOD).
Before I get into that, to provide an initial reference, here’s an estimated table of “Usable” battery capacity (in Amp-hours) needed to operate various types and sizes of refrigerators for one day:
| Fridge type | Fridge Size (Cubic feet) | Daily Energy Consumption (Watt-hours) | Required Usable Battery Capacity (Amp-hours) at 12 Volts |
| 12V Fridge | 2 Cu. ft. | 350Wh | 30 Ah |
| Mini-fridge | 4 Cu. ft. | 600Wh | 50 Ah |
| RV fridge | 10 Cu. ft | 1000Wh | 85 Ah |
| Residential fridge 1 | 18 Cu. ft. | 1500Wh | 125 Ah |
| Residential fridge 2 | 25 Cu. ft. | 2000Wh | 170 Ah |
For instance, on average, the energy consumption of a mini-fridge is estimated to be around 600 Wh (Watt-hours) per day.
Therefore, to run your average mini-fridge for 24 hours on a battery, without having to recharge the battery, the battery should have a “Usable Energy Capacity” of 600 Watt-hours (Wh), which equates to a “Usable Charge Capacity” of 50 Amp-hours (Ah) if the battery is rated at 12 Volts.
So, a 12V – 50 Ah battery should be able to run a mini fridge for a whole day on a single charge, right?
Well, yes and no. Let me explain.
A battery’s capacity is quantified using 2 ratings:
- The battery’s Voltage in Volts (V for short)
- The battery’s Charge Capacity in Amp-hours (Ah for short)
Using these 2 ratings, we can determine the Energy Capacity of the battery, which represents the amount of Electrical Energy, in Watt-hours (Wh) or kiloWatt-hours (kWh), that the battery can store and supply:
Energy Capacity (Watt-hours) = Voltage (Volts) x Charge Capacity (Amp-hours)
For example, consider a 12V – 100 Ah battery:
The amount of energy (in Watt-hours) that this battery is capable of supplying on a single charge is calculated as such:
Energy Capacity (Watt-hours) = Voltage (Volts) x Charge Capacity (Amp-hours)
Energy Capacity (Watt-hours) = 12 Volts x 100 Amp-hours
Energy Capacity (Watt-hours) = 1200 Watt-hours
Energy Capacity (kiloWatt-hours) = 1.2 kWh
However, other than their rated capacity, batteries also come with a recommended Depth Of Discharge (DOD) that specifies the percentage of their capacity that can actually be used without significantly decreasing the lifespan of the battery.
This is due to the fact that batteries have a finite number of charge/discharge cycles before a significant portion of their rated capacity is lost. The deeper you repeatedly discharge a battery, the faster its overall capacity degrades.
Related: How long will a 100Ah battery last?
So, even though the battery from our example is capable of supplying 1200 Wh of energy on a single charge, it generally wouldn’t be recommended to use all that amount of energy every time you discharge the battery.
The recommended DOD of the battery will determine the actual amount of energy that it can safely supply on a single charge, a.k.a, its “Usable Energy Capacity”:
Usable Energy Capacity (Watt-hours) = Rated Energy Capacity (Watt-hours) x Depth Of Discharge (DOD) (%)
Similarly, the “Usable Charge Capacity” of the battery is calculated as such:
Usable Charge Capacity (Amp-hours) = Rated Charge Capacity (Amp-hours) x Depth Of Discharge (DOD) (%)
For example, if your refrigerator requires 1200 Wh per day to run, it means the battery has to have a Usable Energy Capacity of 1200 Watt-hours, which equates to a Usable Charge Capacity of:
- 100 Amp-hours if the battery’s rated at 12 Volts.
- 50 Amp-hours if the battery’s rated at 24 Volts.
- or 25 Amp-hours if the battery’s rated at 48 Volts.
And if, for instance, the battery has a recommended DOD of 50%, it should be rated at 2400 Watt-hours to be able to supply 1200 Watt-hours, which equates to a Rated Charge Capacity of:
- 200 Amp-hours if the battery’s rated at 12 Volts.
- 100 Amp-hours if the battery’s rated at 24 Volts.
- 50 Amp-hours if the battery’s rated at 48 Volts.
Now, the DOD of a battery will depend on the specific model and what its manufacturer recommends.
For example, the manufacturer of this 12V-100Ah Li-time battery claims the battery will last up to 4000 Charge/Discharge Cycles at a DOD of 100%. This means the battery can repeatedly supply 1200Wh of energy on a single charge, and will last up to 11 years at 1 charge/discharge cycle per day.
For comparison, the manufacturer of this 12V-100Ah Renogy battery claims 500 Charge/Discharge cycles at a DOD of 50%, which equates to about 1.5 years at 1 charge/discharge cycle per day.
In general, the chemistry of the battery will dictate how deep you’ll be allowed to discharge the battery. Lead-Acid batteries will typically have a recommended DOD of 50%, and Lithium batteries a recommended DOD of 80%:
| Battery Chemistry | Recommended Depth of Discharge (DoD) |
| FLA (Flood Lead-Acid) | 50% |
| SLA (Sealed Lead-Acid) | 50% |
| AGM (Absorbed Glass Matt) | 50% |
| Li-Ion (Lithium Ion) | 80% |
| LiFePO4 (Lithium Iron Phosphate) | 80% |
If we use these typical recommended DODs as a reference, here’s a table that estimates the daily energy consumption of different refrigerator types and sizes, and provides the required battery size to run each of them for a day:
| Fridge type | Fridge Size (Cubic feet) | Daily Energy Consumption (Watt-hours) | Required Lithium Battery Rating | Required Lead-Acid Battery Rating |
| 12V Fridge | 2 Cu. ft. | 350Wh | 12V – 40Ah | 12V – 60Ah |
| Mini-fridge | 4 Cu. ft. | 600Wh | 12V – 70Ah | 12V – 120Ah |
| RV fridge | 10 Cu. ft | 1000Wh | 12V – 120Ah | 12V -200Ah |
| Residential fridge 1 | 18 Cu. ft. | 1500Wh | 12V – 200Ah | 12V – 300Ah |
| Residential fridge 2 | 25 Cu. ft. | 2000Wh | 12V – 250Ah | 12V – 400Ah |
Keep in mind that these estimates are approximations and serve as a starting point to give you an idea of the battery capacity needed for your refrigerator.
In the next section, I will explore a more accurate method to determine the precise battery bank size required to run your fridge.
Calculate the battery capacity required to run your refrigerator:
The exact size of the battery that you need to run your refrigerator depends on 3 factors:
- The daily energy consumption of your refrigerator.
- The number of days for which the battery bank should be able to power your refrigerator.
- The recommended Depth Of Discharge (DOD) of the battery
Once these variables are determined, you can calculate the exact size of the battery bank via one of the following formulas:
1- If your refrigerator runs on DC (Direct Current) power:
Required Energy Capacity (Watt-hours) = (Refrigerator’s daily energy consumption (Watt-hours) x Number of days) ÷ DOD (%)
2- If your refrigerator runs on AC (Alternating Current) power:
Required Energy Capacity (Watt-hours) = (Refrigerator’s daily energy consumption (Watt-hours) x Number of days) ÷ (DOD (%) x 0.85)
Please Note: If your refrigerator uses AC power, you’ll need to account for the efficiency of the inverter. The 0.85 factor in the 2nd formula is used to simulate an inverter efficiency of 85%.
Once you’ve calculated the required battery bank’s energy capacity (in Wh), you’ll easily be able to determine the number of batteries that will be required.
Before I provide a couple of examples that illustrate this, let’s first talk about the energy consumption of your refrigerator and a couple of ways to determine it.
How much energy does your refrigerator consume?
When it comes to determining the energy consumption of your refrigerator within a specific timeframe, you have a couple of options for estimating or measuring it.
One convenient approach is to refer to the EnergyGuide label typically provided with the refrigerator. This label offers an estimate of the appliance’s annual energy consumption, providing valuable insights into its energy usage and efficiency.
For instance, take a look at the image below, which showcases the estimated yearly energy consumption of a 4.5 cubic feet mini-fridge:
By dividing the yearly energy consumption of 237 kWh by 365 days, we can estimate that the daily energy consumption is approximately 0.65 kWh (650 Wh).
Estimated Daily Energy Consumption (kiloWatt-hours) = Estimated Yearly Energy Consumption (kiloWatt-hours) ÷ 365
Estimated Daily Energy Consumption (kiloWatt-hours) = 237 kWh ÷ 365
Estimated Daily Energy Consumption (kiloWatt-hours) = 0.65 kWh
Estimated Daily Energy Consumption (Watt-hours) = Estimated Daily Energy Consumption (kiloWatt-hours) x 1000
Estimated Daily Energy Consumption (Watt-hours) = 0.65 kWh x 1000
Estimated Daily Energy Consumption (Watt-hours) = 650 Wh
This method provides a rough estimate, but if the EnergyGuide label is not available, you can turn to the electrical specifications of your refrigerator.
For example, here’s the specification sticker on an 18 cubic feet refrigerator:
Look for the power usage of the refrigerator in Watts on the specification label, often indicated as “Rated Input,” “Rated Power,” “Wattage,” or “Power Usage.”
On this particular label, you’ll notice that the manufacturer specifies 100 Watts as the “Rated Input” (Power usage or Wattage) of the refrigerator.
Before explaining how you can use the power usage (in Watts) to estimate energy consumption, it’s worth noting that sometimes the power usage is not directly specified. In such cases, you can calculate the power usage using the rated Current (in Amps) and Voltage (in Volts) of the fridge:
Power Usage (Watts) = Voltage (Volts) x Current (Amps)
In this example, the manufacturer specifies 0.45 Amps as the rated Current and 220-240 Volts as the rated Voltage. Assuming an average voltage of 230 Volts, we can calculate the power usage of our refrigerator:
Electrical Power (Watts) = 230 V x 0.45 A
Electrical Power (Watts) = 103.5 Watts
Notice that the Rated power usage (100 Watts) and the calculated power usage (103.5 Watts) are almost equal to each other.
Since it is better to overestimate the energy consumption of the fridge, than to underestimate it, we’ll be using 103.5 Watts for the rest of this explanation.
Now that we know the power usage of our refrigerator, how can we use it to estimate its daily energy consumption?
Well, as a rule of thumb, the energy consumption of a refrigerator over a certain period of time can be calculated as such:
Energy Consumption (Watt-hours) = Power Usage (Watts) x Usage Duration (hours) x 0.33
Since we’re trying to figure out the daily energy consumption of the fridge, the formula becomes:
Energy Consumption (Watt-hours) = Power Usage (Watts) x Usage Duration (hours) x 0.33
Energy Consumption (Watt-hours) = Power Usage (Watts) x 24 hours x 0.33
Energy Consumption (Watt-hours) = Power Usage (Watts) x 8 hours
If we use 103.5 Watts as the rated wattage of the fridge, its daily energy consumption can be estimated as such:
Energy Consumption (Watt-hours) = Power Usage (Watts) x 8 hours
Energy Consumption (Watt-hours) = 103.5 Watts x 8 hours
Energy Consumption (Watt-hours) = 828 Watt-hours
Both of the methods explained above provide quick estimates specific to your refrigerator, giving you a starting point. However, for the most accurate measurement, using an electricity monitoring device is recommended.
An electricity monitoring device, such as the Kill-A-Watt meter, offers precise measurements of the energy consumption of your refrigerator.
With a Kill-A-Watt meter, you can simply plug your refrigerator into the device and monitor its real-time energy usage. This allows you to track the exact energy consumption over a specific period and obtain more accurate data.
In any case, once you have an energy consumption estimate/measurement, you’ll be able to calculate the size of the battery that you need to run your fridge via one of the formulas previously provided.
Here are a couple of examples:
Example 1:
Consider a 12 Volt car fridge/freezer that consumes around 450Wh per day., and let’s make the following assumptions:
- I want the battery bank to be able to run the fridge for 2 days.
- I’ve decided to use a LiFePO4 (Lithium) battery bank to power the fridge, and I’ll go for a Depth Of Discharge (DOD) of 80%.
Since this is a 12V car fridge, it uses DC power and won’t require an inverter. Therefore, we won’t need to account for inverter losses, and we’ll be using the following formula:
Required Energy Capacity (Watt-hours) = (Refrigerator’s daily energy consumption (Watt-hours) x Number of days) ÷ DOD (%)
Required Energy Capacity (Watt-hours) = (450 Watt-hours x 2 days) ÷ 80%
Required Energy Capacity (Watt-hours) = (450 Watt-hours x 2 days) ÷ 0.8
Required Energy Capacity (Watt-hours) = (900 Watt-hours) ÷ 0.8
Required Energy Capacity (Watt-hours) = 1125 Watt-hours
To run our 12V fridge for 2 days on a lithium battery bank, we’ll need a minimum Rated Energy Capacity of 1125 Watt-hours.
A good fit would be this 12V-100Ah Li-Time lithium battery, as it has a Rated Energy Capacity of 1200 Watt-hours.
Example 2:
For this example, let’s consider a typical RV refrigerator that consumes 1000 Wh per day, and let’s make the following assumptions:
- As a backup, I want the battery bank to be able to run the fridge for 3 days.
- I’ve decided to use an AGM (Lead-Acid) battery bank to power the fridge, and I’ll go for a Depth Of Discharge (DOD) of 50%.
- The refrigerator uses 120V AC power, so I’ll need an inverter to run the fridge.
The inefficiency of the inverter needs to be considered, therefore, we’ll be using the following formula:
Required Energy Capacity (Watt-hours) = (Refrigerator’s daily energy consumption (Watt-hours) x Number of days) ÷ (DOD (%) x 0.85)
Required Energy Capacity (Watt-hours) = (1000 Watt-hours x 3 days) ÷ (50% x 0.85)
Required Energy Capacity (Watt-hours) = (1000 Watt-hours x 3 days) ÷ (0.5 x 0.85)
Required Energy Capacity (Watt-hours) = (3000 Watt-hours) ÷ (0.425)
Required Energy Capacity (Watt-hours) = 7058 Watt-hours
To be able to run our RV fridge for 3 days on a lead-acid battery bank, we’ll need a minimum Rated Energy Capacity of 7058 Watt-hours.
If we use these 12V-100Ah AGM batteries from Renogy, which each have a Rated Energy Capacity of 1200 Wh, the number of batteries we’ll require is calculated as such:
Number Of Batteries = Required Energy Capacity (Wh) ÷ Rated Energy Capacity Of Each Battery (Wh)
Number Of Batteries = 7058 Wh ÷ 1200 Wh
Number Of Batteries = 5.88
According to our calculations, 6 12V-100Ah AGM batteries will be required to run the refrigerator.
Now, let’s use this particular example to explore the cost implications and alternatives for powering the refrigerator beyond the battery bank alone.
To run a refrigerator that requires 1000Wh of energy on a daily basis solely on batteries, for 3 days, the battery bank alone, consisting of 6 12V-100Ah AGM batteries, will cost around 1150 USD.
Additionally, you’ll need an inverter, which typically costs around 150 USD. In total, the battery bank setup will amount to approximately 1300 USD to provide 3 days of refrigerator runtime.
However, it’s worth considering a more cost-effective and sustainable option. You can opt for solar panels to run your refrigerator, which offers a more affordable, efficient, and long-term solution.
For instance, by using 2 12V-100Ah AGM batteries (380 USD), 300 watts of solar panels (270 USD), an MPPT charge controller (150 USD) to regulate the solar panel output, and an inverter (150 USD), the entire system would cost around 950 USD.
Additionally, apart from being approximately 30% less expensive, the utilization of solar panels in conjunction with batteries provides the added benefit of powering your refrigerator indefinitely, with no constraints on duration, given an adequate amount of sunlight.
Click here to learn more about sizing a solar system that can run your refrigerator.
In any case, as previously mentioned, if your refrigerator uses AC power, an inverter will be required.
What size inverter do you need to run a refrigerator?
Batteries supply power at a low voltage range (12-48 Volts) in the form of DC (Direct Current), which is fine if you’re trying to run a 12V car fridge. However, most refrigerators require a higher voltage (120 Volts) AC (Alternating Current) power, which is what you’d get from a typical wall outlet in the U.S.
In order to convert this low-voltage DC power from the battery bank into the required higher-voltage AC power, an inverter will be necessary.
In most cases, a 1500W pure sine wave inverter will suffice for running a refrigerator. However, in my comprehensive step-by-step guide on inverter sizing for refrigerators, I discuss all the crucial specifications that you should consider. These specifications include:
- The Continuous Power rating of the inverter (in Watts): This represents the amount of power that the inverter is able to continuously supply. The continuous power rating of the inverter should be greater than the power usage of your refrigerator.
- The Surge Power rating of the inverter (in Watts): This represents the maximum amount of power that the inverter is able to supply for a brief moment when necessary. The surge power rating of the inverter should be greater than the amount of power that your refrigerator uses when turning on.
- The Input Voltage rating of the inverter (in Volts): This refers to the voltage range that the inverter is designed to accept at its input. It is important to ensure that the input voltage rating of the inverter matches the voltage supplied by the battery bank.
- The Output Waveform of the inverter: This refers to the shape of the electrical waveform produced by the inverter on its output. Common output waveforms include Pure Sine Wave (PSW), Modified Sine Wave (MSW), and Square Wave (SW). To operate your refrigerator efficiently and prevent any potential problems or harm, you’ll need to use a Pure Sine Wave inverter.
For a more detailed understanding of these specifications and to make an informed decision, please click here.
I am trying to understand batteries and their capacities. I am trying to figure my usage of power, to build out a trailer to travel, with solar, auto regeneration,and a smal wind turbine.
Any ideas?
Namaste,
Victoria Drake
Fort Worth Texas
[email protected]
Hey man.
the page is awesome i need your advise on the putting a power station together please man.
Read your article, easy to understand.
I have a small 2 cu ft whirlpool fridge, uses .8 Amp, 120v 60hz, ,and 1000w inverter, and 105 amphr battery, lead acid., I turned off shore power and plugged the fridge to 1000w inverter. Fridge ran for 45 minutes, then inverter shut down. Battery voltage started at 12.7 v and leveled off at 12.4v.
I could not get the fridge to run after 45 min. Checked the voltage out of inverter, 109v.
Does this mean that my battery is not converting enough voltage to run fridge? I have a 4500w generator on board to charge battery.
Is my fridge too big or my battery too small?
I would like to run my fridge min 2 to 3 days on the water.
Can you please help me out? Do I go solar?
How many hours run time will I get using 2 100ah agm batteries assuming they are only discharged 50% running a 90watt 80lt dual zone fridge freezer. I have a 300watt solar panel running a 30amp mppt charge controller? I will be using the fridge 24/7 but from what I have read the compressor is only working for about 8 hours a day?
2 12V-100Ah will provide 1200 Watt-hours (1.2kWh) if usable energy. a 90W fridge/freezer will generally uses about 750 Watt-hours per day. The batteries alone will be enough to run the refrigerator for about 40 hours. However, combined with a 300W solar panel, the fridge/freezer should be able to run indefinitely if enough sunlight is provided.
Please refer to this article, as it encompasses all the info you’ll need on running a fridge on solar power.
Hope this helped.
Dear Younes,
I am considering buying a Li-on Power Unit to run my Fridge-Freezer for, potentially, three days of power outage.
I live in a flat and am unable to use solar panels (unless there are mini-panels that would fit on a window ledge) so will have to rely on being able to re-charge via a three pin wall socket.
I only know that my Ffreezer uses 215 kWh per year (0.59 per day) and am totally unable to tell the difference between W – Wh -Amps – Ah or to do the maths required to sort out what power I would need.
So my apologies if I cannot understand your extremely informative web page, but any information you could give me would be appreciated.
Regards,
Jay
Hey there Jay, no worries.
I wrote an article that explains some of the important aspects of electricity and their measurement units, such as amps, volts, and watts, which you can find here.
I also wrote an article on the different between Watts (or kiloWatts) and Watt-hours (or kiloWatt-hours), which you find here.
As to your initial question, I believe one 12V-100Ah li-time battery will be sufficient to run your fridge/freezer for 2 days if needed, as these batteries have an energy capacity of 1.2 kWh. Two of those batteries will provide 2.4 kWh of energy.
Hope this helps.
You probably gave a lot of great information .but for me it was a little too difficult to understand .I was just trying to figure out how many marine batteries I would need to run a frigerator. A rough estimation 3 4 5 batteries just to get a estimated amount. great job.
This is been very helpful and I appreciate you taking your time to help others! I am an absolute beginner in solar and trying to convert a class C RV, and would appreciate any suggestions!
feel free to leave any specific questions that you have, I’d be happy to help.
Hi there. Thank you so much for this information. It is very helpful.
Can I ask for some related information? I have a small travel trailer (TAG) and am swapping out a 24 series lead battery for lithium (100 Ah). The only “big” energy user is my Norcold NRF30 cooler, which uses 4.3 amps. Other uses (minimal) are LED lights. I am quick certain that my new battery will be more than enough, based on your commentary.
However, I am also interested in a solar top-up solution to keep the batteries charged so that I can keep the cooler going for several days.
Do you have any recommendations?
Thank you!
To understand more about battery capacity and how to determine it, I recommend reading this article, as I believe it provides all the resources you’ll need.
As to the solar top-up solution, please refer to this article, in which I explain in detail the process of sizing a solar array for fridge/freezers/coolers.
Hope this helps.