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A mini fridge is a convenient option for any road trip, especially for those who enjoy off-grid adventures. While relying solely on a car battery to keep it running is possible, it presents some challenges since car batteries are not designed for running appliances. It can reduce its runtime or leave you stranded if you drain your battery too much.
We will examine the factors affecting your runtime, including energy consumption, capacity, temperature, etc and show you how to calculate how long your fridge could run on your power supply.
Let’s get started.
Understanding the Basics
Before we get into what affects the running time of your refrigerator on batteries, let’s ensure you understand what we’re talking about.
Mini Fridges
Nowadays, mini fridges come in multiple models and sizes with various power source options. Some run on 12V electricity from a vehicle, some on AC wall plugs, others on propane, and still others on solar energy. No matter what your fridge takes, most still have multiple options for charging it. Using a car battery is only one of the many ways to charge a portable refrigerator.
For instance, the EcoFlow Glacier Portable Refrigerator will last up to 40 hours wirelessly on the charge it holds in its internal batteries. However, exactly how long it will last depends on how you use it. For instance, it can depend on how cold the temperature is set, how often you open and close it, and the temperature outside.
The beauty of this model is that when it does need recharging, it can take direct solar, an AC wall plug, your 12V car plug, a portable power station, or a generator for the most versatile recharging options.
Car Batteries
Car batteries are critical components of a vehicle’s electrical system. They provide the energy needed to start the engine, run the lights, and various accessories, especially if you have power windows, heat, or AC. They also provide energy to the 12V socket, which you can also use to run devices and appliances.
Car batteries are designed to deliver a short burst of power to start the engine and then small amounts of power while running to keep the lights and other essentials on. However, they’re not designed for long-term deep discharge, like using them to run a refrigerator for long periods, especially when the car isn’t running.
This is essential to understand. Car batteries should never be fully discharged, as this can significantly reduce their lifespan and leave you stranded when they die.
Factors that Affect Running Time
Battery Capacity
Capacity is a huge factor as it determines how long you can run anything without a recharge. A higher-capacity model provides more power and, therefore, runs your refrigerator longer.
For example, if you have a standard 70Ah lead-acid car battery, you could run a 2A mini fridge for 35 hours. However, it’s impossible to discharge lead-acid models to OAh as they will die before that, and draining them until they are dead significantly shortens their lifespan.
Battery Age and Condition
This also plays a huge role as ageing batteries, or those already drained until dead a few times, will not last long. In fact, aging batteries might not even give you an hour of runtime.
Fridge Power Consumption
Portable fridges come in various sizes, so of course, they also vary significantly in how much energy they use. Check the Watts of your model to determine how much it uses while running. The more watts it uses, the less time you can run it on your battery.
Say your fridge uses 120 Watts and a 12V power supply. If you have a 70Ah battery, then you can estimate the runtime using the following calculation:
Runtime (hours) = Battery Capacity (Ah) ÷ Fridge Power Consumption (A) Runtime (hours)
Note that you can convert between Amps and Watts as follows: Amps = Watts ÷ Volts.
Therefore:
Runtime = 70Ah ÷ (120W ÷ 12V) = 7 hours
Temperature Control
The colder your refrigerator is, the more energy it uses to maintain that temperature. However, this doesn’t necessarily mean you should turn the temperature up to make it last longer.
You’ll need to keep it at a food-safe level, especially if you keep meats or dairy. Food-safe fridge temperatures are at 4°C (40°F).
Ambient Temperature
Another factor is the temperature outside. When the weather is hot, the fridge must work harder to keep it cool, so it draws more energy because the compressor has to run continuously.
Conversely, if it’s cold outside, the compressor can shut off more frequently, saving significant energy compared to running it in warm weather.
Practical Tips to Extend a Mini Fridge Runtime
There are several ways you can extend the runtime of your mini fridge and keep food colder longer.
- Keep the fridge door closed as much as possible.
- Insulate your refrigerator with a thermal blanket wrapped around it.
- Invest in deep-cycle batteries that can be discharged completely, or better yet, build a portable power station with solar panels, and you can run it indefinitely.
- Precool the refrigerator and the contents at home before you leave. It’ll reduce the strain on your car battery.
- Optimise the temperature for food safety at 4°C (40°F); setting it lower will drain your power supply faster.
- If your refrigerator has built-in batteries, charge it while you drive instead of while you are parked. Your car’s alternator keeps your battery topped up while you drive, so it won’t run out.
- If you have a voltmeter or battery monitor in your car, use it to monitor your voltage. This will help you take precautions to avoid draining your battery excessively.
Alternative Power Sources
Of course, you can always expand your energy capacity using an EcoFlow Portable Power Station, which comes in various models and capacities, including enough to power your home, which is helpful with Eskom’s struggling electrical system.
Understanding your capacity is important to knowing how long your appliances will run. Use the same calculation above to determine how much capacity you need.
When travelling by car, we may have to choose between capacity, size and weight. The greater the capacity, the more it weighs and the more space it takes up. What is most important depends on your needs.
For instance, if you prioritise capacity, the EcoFlow DELTA Series Portable Power Stations are robust models that can run numerous appliances, including your refrigerator, for as long as you need it, depending on the capacity you get.
If you plan to be off-grid for days or weeks at a time, it’s important to choose a solar generator that will reliably power your fridge.
However, if you are travelling in a small vehicle or need to pack your power station around with you, size might be more important to you. In this case, the EcoFlow RIVER Series Portable Power Stations are much more compact and lightweight but can still keep your fridge running for a while.
In fact, the EcoFlow RIVER 2 Pro is considered to be the best compromise between capacity and portability for those of us who prioritise both and don’t want to make a trade-off between capacity and size.
Frequently Asked Questions
It can vary widely depending on how much power the refrigerator uses and the battery’s capacity. In general, however, it could run a mini fridge anywhere from about 4 – 20 hours.
How long a car fridge will run on car batteries depends entirely on how much energy the refrigerator uses, how much capacity the battery has, and how carefully you use your fridge. However, you could generally run it from about 4 – 20 hours.
Yes, a mini fridge can easily drain batteries when a car is parked for too long without running the alternator to keep it charged. Monitor your battery voltage, and start your car occasionally if you need to rely solely on it to keep your fridge cold.
Final Thoughts
It’s certainly possible to run a mini fridge using car batteries, but be wary of running it until it dies, as this will significantly reduce its lifespan. Therefore, monitor the voltage and recharge it before it runs out entirely.
The best option, however, is to invest in an alternative power source to help extend runtime and prevent unexpected battery drain. For longer trips, portable power stations are the best option. They can be recharged with solar panels, so you can keep your appliances running indefinitely without compromising your vehicle’s battery.