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Are you looking for a way to keep your drinks or food cold when out camping? Then, you should consider a 12V fridge or freezer.
They are generally energy-efficient and consume less energy compared to the larger domestic AC fridges. If sized well, a 12V battery can keep the fridge running for several hours in a day.
To connect the fridge to the battery, depending on the design of the fridge, you’ll likely need a cigarette lighter plug (provided) that you can plug into the vehicle’s cigarette lighter socket or a portable power station. Should your fridge or freezer fail to work, confirm that the battery is sufficiently charged.
You can use a digital voltmeter to measure the battery voltage. Some fridges also have a display where you can read the battery voltage.
They usually have a battery protection mode where they prevent damage to the battery from deep discharge should the voltage drop to a specified set-point usually 10.1 or 11.1V.
Consult the fridge manual for the low voltage cut-out limits.
What is the Best Battery Type to Power a 12V Fridge?
You can connect the 12V fridge to a deep cycle AGM, Flooded Lead Acid battery, or Lithium battery.
Whenever possible connect to a Lithium battery type. It is lighter which makes it suitable for use in portable fridges or freezers.
Lithium batteries also have more usable capacity than both AGM and flooded Lead Acid batteries (FLA) though they cost more than either battery type.
AGM batteries are also a good option to consider. Compared to the lithium battery type, they are more affordable yet have a reasonable depth of discharge of 50%.
Benefits of AGM, Lithium and Flooded Lead Acid batteries Compared
|AGM||Generally cost less than Lithium batteries|
|Should only be discharged to 50% of their capacity for good battery life|
|Lithium||Longer lifespan compared to AGM or Flooded Lead Acid batteries|
Less physical space and lighter
More usable capacity – can be discharged to 80% of capacity without significant reduction in battery lifespan
|Cost more compared to AGM or Flooded Lead Acid batteries|
|Flooded Lead Acid (FLA)||Cheaper compared to AGM or Lithium batteries||Prone to spills and need to be installed in a place with good air circulation|
Which Battery type to Use
To power a 12V fridge or freezer, use deep-cycle AGM or Lithium instead of the car starter battery. They are better suited to supplying power to fridges over several hours.
Car starter batteries on the other hand are designed to provide high startup currents for a short time and will not last when used to power a fridge or freezer.
Can You Power a12V Fridge or Freezer with a 100Ah Battery?
You can power a 12V fridge using energy from a 12V, 100Ah battery, or any other battery capacity provided that it is sufficiently charged and matches the fridge voltage (12V or 24V). The battery capacity should be sized to avoid being deeply discharged which can affect its lifespan. This assumes a fridge with a power consumption of between 45-90W.
How Long a 100Ah Battery Runs a 12V Fridge or Freezer
A 12V 100Ah AGM battery can supply a 12V fridge with enough power to run the fridge continuously for about 6-13 hours. This assumes a fridge with a power consumption of between 45-90W.
With a Lithium battery, the fridge can run continuously for an estimated 10 – 21 hours as the lithium batteries have more usable battery capacity (80%).
What if the fridge’s power consumption is different (not 45-90W)?
In this case, you can use this handy formula:
How long the fridge runs continuously (hours) =( Battery capacity (Ah) x Depth of discharge of battery (50% for AGM and 80% for Lithium) x Battery voltage (12V)) / fridge or freezer’s power consumption (watts)
For example, if the fridge’s power consumption is 100 watts. To get an estimate of its runtime with a 100Ah AGM battery,
(100Ah x50%x 12V)/100 watts = 6 hours
Note: Actual runtime may vary and in fact, will likely be longer as the fridge does not run continuously and instead cycles on and off to maintain the set temperature.
Other factors that determine how long the fridge can run are if the fridge contents were previously chilled, how often the fridge door is opened, and if it is placed in a shade or not.
For the fridge or freezer to run longer, whenever possible only place fridge contents that are at room temperature at most, if possible chill them before. Avoid warm or hot items.
Place the fridge in a shade and minimize the number of times the door is opened.
Indicative Runtimes with Different Battery Capacities (Ah)
Note: This assumes a 45-90W, 12V fridge connected to fully charged 50Ah, 200Ah AGM, and Lithium batteries to run your fridge.
|Battery type||50Ah/ 12V||100Ah / 12V||200Ah / 12V|
|AGM||3 – 6.5 hours||6 -13 hours||12 – 26 hours|
|Lithium||5 – 10 hours||10 – 21 hours||20 – 40 hours|
Tips to Maximize How Long a 12V Fridge or Freezer Runs on Battery
Here are some of my top tips for getting as much runtime from your battery as possible:
- When outdoors, keep the fridge/ freezer in a shaded area
- Whenever possible, chill drinks or foods the night before. This reduces the fridge’s energy consumption as its compressor does not have to work as hard to keep them cold.
- Disconnect the fridge’s battery or switch it off when the fridge is not in use. This eliminates energy drawn from the battery when on standby.
How many Batteries to Run a 12V fridge/freezer?
This depends on the desired runtime for the fridge, the space available for the batteries, and the allowed weight for the batteries.
That said, with your 45 -90W fridge or freezer, you can consider 1 pc 12V 100Ah AGM battery or 2 pcs 50Ah batteries to run your 12V fridge for approximately 6 to 13 hours continuously.
Note: This is just one of the possible battery configurations you can use.
#1. How to Power a 12V Fridge or Freezer?
Use a 12V cigarette lighter extension cord that you can plug into the car’s cigarette lighter socket. Make sure to keep the car engine running to keep the car topped up!
You can also run the mini fridge off a suitably sized portable power station. Check that the portable power station or vehicle battery has enough capacity to meet the energy requirements of the 12V fridge or freezer.
Lastly, you can also connect the fridge to an off-grid solar panel, charge controller, and battery bank system. Check the battery system can meet the power requirements of the 12V fridge to avoid draining and damaging the battery.
Note: Some portable fridges/freezers have a low voltage disconnect or battery saver system that switches off the battery when its voltage is getting dangerously low to prevent your car’s battery from being drained.
Make sure this feature is activated on your fridge or freezer.
What Size of Solar System to use with 12V fridge?
This is an example of a solar system that you can use to keep a fridge or freezer with a power consumption of under 1 kWh a day running.
Note: This is just one of the possible setups you can use.
- 50Ah AGM battery
- 100W solar panel
- 20-30A charge controller
or a 105W solar panel only in case the fridge/freezer has a 50Ah AGM or 15Ah Lithium inbuilt battery
#2. What Size Solar Panel to Run a 12V Fridge or Freezer?
The solar panel size needed to run your fridge depends on the fridge’s power consumption and intended duration of operation during the day.
The table below shows indicative solar panel capacities (w) to use with 12V fridges. Note, this is a guide, consult your fridge/freezer manufacturer for guidance.
|No||Fridge/ freezer power consumption (watts)||Estimated solar panel capacity (watts)|