How to Use a Portable Power Fridge Without Draining Your Battery

The time-honored way to keep things cold during a car trip is an ice-filled cooler. It works as long as replacement ice is readily available, and you don’t have anything in the cooler that could be ruined by the inevitable water bath from melted ice. Because these requirements can’t always be met, a product has emerged known as portable electric coolers or car fridges. The first question that comes to mind with these items is how you can use them without draining your battery. This Michael Hohl Subaru blog can help you with that.

Car fridges come in several types, including thermoelectric, absorption, and compressor models. Thermoelectric models are lightweight and budget-friendly but less efficient than compressor fridges, which offer superior cooling performance. Absorption fridges operate silently and can use various power sources, making them flexible, though they tend to be pricier. They are designed to run on 12V power from your car battery, though some can run on AC power from an outlet. Compressor fridges work like air conditioners, using a refrigerant and a compressor for cooling, and, like air conditioners, they can use a fair amount of energy. That immediately raises the concern of draining a car battery. And yet, the items exist, so what is the secret?

Pre-Chill the Contents

The first step in making the best use of a portable power cooler occurs before the trip. Make sure all the cooler contents are already cool. For perishable items, this is a given, but it also applies to beverages. This both reduces the cooler’s workload and helps keep the cold items cool when the fridge is not powered.

Pack the Fridge Efficiently

Organize the contents to ensure proper air circulation and keep frequently accessed items on top to reduce how often the fridge door is opened. If you have room, pre-frozen ice packs can help the fridge maintain a cool temperature when powered down.

Plug in the Cooler When the Vehicle is Running

Like the vehicle’s own air conditioning system, the cooler will not drain the battery while the car is running. Power will come from the alternator, which powers all the rest of the car’s electronics. These units expel heat as they operate, so be sure the fridge’s heat vent is not blocked when packing.

Trust the Insolation

Like ice coolers, portable fridges are well insulated and designed to keep the cold in when they are not powered. If you are out for a day trip, the cooler may stay cold throughout your outing, depending on how often it is opened and how well the contents retain cold. Liquids and steel retain cold well. Solid, dry items less so. This works better, of course, if the fridge is in the shade.

Battery Saver Mode

Most modern Subaru models are designed to cut off accessories and accessory outlets to prevent the 12-volt battery from fully draining. You may want to test this when you know you have a backup, such as someone who can give you a jump. If it works, you will be able to use your fridge with more confidence. Some portable fridges have sensors that shut down when they detect a weakening power source.

Extra Battery with Relay Isolator

If you have one on hand, you can use a second 12-volt battery. Ideally, you would connect it to the standard car battery so the alternator can charge it. The relay isolator is designed to prevent the fridge’s power draw from draining the primary car battery, so it can be counted on to start your vehicle.

Portable Solar Panels

If you can count on the sun where you stop, consider a portable solar panel paired with a deep-cycle battery. The battery can receive power from the panel and, in turn, power your fridge. The panels are usually collapsible and open up to be about a foot by a couple of feet.

Keep Jump-Start Equipment On Hand Just In Case

If you are meeting people who drove separately, keep jumper cables on hand in case all else fails. If you are going somewhere alone, bring a portable charger instead.

As mentioned, most modern Subaru models have a battery saver system to prevent your Subaru’s battery from being drained by a portable fridge or any accessory. Read about it in the owner’s manual. If you have a vehicle from a different brand, check whether it has a battery-saver system, or, of course, you could simply replace it with a new or used Subaru from Michael Hohl Subaru.