How To Run An Electric Heater Off A Car Battery [Step By Step Guide For Extreme Weather]?

Are you planning to go on a camping trip in the winter, and you want to know how to run an electric heater off a car battery in case the temperature becomes too cold? Or perhaps you’d like to be ready for a power outage during the cold months? You’ve come to the right place, for we have researched this question, and we have the answer for you.

To run an electric heater off a car battery, you will need a transformer, an inverter, and the car battery. Connect the electric heater to a transformer, then connect the transformer to the inverter, and connect the inverter to the car battery.

Let’s discuss the different things you need to power your electric heater and how they work together in the succeeding sections. Learn more about how to supplement your car battery below.

Read on!

Automotive technician connecting vehicle battery to the wire cable, How To Run An Electric Heater Off A Car Battery [Step By Step Guide For Extreme Weather]?

How to pick an electric heater?

Electric tent heaters are safer than propane gas or halogen heaters -especially if you're using them to warm a tent. They are also lightweight; you don’t need a separate propane tank to power your heater.

The only disadvantage of an electric tent heater is that it can consume large amounts of electricity. This means that you will need a way to supplement the power from your car battery at some point, but more on this later.

Before we talk about how to power your electric heater off your car battery, let’s briefly look at some tips on picking the best electric tent heater for your trip.


White domestic electric heater on floor

Getting a portable yet powerful electric heater means you don’t have to give up much space in your car when packing, and you still get the right amount of heat for your tent. However, remember that the ideal electric heater is not always the smallest. You may save a lot of space in your car but fail to get the right amount of heat that you need at camp.

It is important to strike a balance between an electric heater with a compact size and one that can produce the right amount of heat. Heaters that are not powerful enough will have to use additional energy to warm up your tent, wasting energy. If the heater is too powerful, your tent will become uncomfortable fast.

Here is a quick guide on determining the amount of heat you need for your tent.

How do you determine tent heater size?

  1. Compute the total volume of space inside your tent. You can typically find this in the tent’s packaging or label.
    • If you don’t find this in the tent’s packaging, multiply the tent's length, width, and height in feet.
  1. Subtract the temperature forecast outside the tent from the ideal temperature you want your electric heater to maintain.
  2. Multiply the total tent volume by the temperature difference and multiply the result by 0.25. The result is the BTU of heat that the electric heater should produce hourly. The 0.25 is the insulation factor of tents.

Included Safety Features

The first safety feature is an auto shut-off function that turns off the electric heater when it becomes too hot. This is an important safety feature to prevent overheating. Overheating can cause the circuits to become too hot and possibly cause a fire.

The second important safety feature is an automatic shut-off function when the heater tips over.

Although many electric heaters are not too warm to touch, this is still an essential feature for heaters. Flammable debris can get into the heater and might generate a spark that can start a fire.

And considering how uneven the floor inside a tent can be, this is a nice feature to have.

Blower Function

Some electronic heaters rely on radiant heat. The natural movement of warm air inside the tent will eventually spread the warmth of a radiant electronic heater.

However, this can take a long time, and in a frigid climate, you could lose the heat faster than it can spread inside your tent.

An electric heater with a blower spreads the heat faster to different tent corners. It’ll be the icing on the cake if it has a swivel function, too.


A heater with a thermostat allows you to set a temperature, and the electric heater will automatically shut down after it reaches the set temperature. This saves your car battery energy, which is vital when you rely on an electric heater for heating.

Amazon Basics 1500W Ceramic Heater is available on Amazon through this link.


Most electric heaters are stable—especially the ones made for use inside the tent. However, it is worth noting that this is an important attribute of heaters. Pick one that is the most stable to prevent tipping over.

Devices You Need To Power An Electric Heater Using A Car Battery

Once you pick up the right electric heater for your tent, the next step is to prepare the devices you need to power your heater. You will need several devices, and we have all of them in a list below, including a brief description of what they do and why you need one.

Do I need a transformer to power a heater with a car battery?

Portable electricity generator (transformer) with big plug and voltmeter

A transformer is an electronic device that changes the voltage. It can increase the voltage or decrease it. The purpose of a transformer in your setup is to align the voltages.

Your electric heater uses 120 volts, while your car battery produces only 12 volts. So, you’d need a step-up transformer to convert the 12 volts from a car battery to the 120 volts that your electric heater needs.

It is important to note here that there are electric tent heaters that do not run at 120 volts. Knowing the voltage your electric heater needs before picking up a transformer for it is essential.

Do I need an inverter to power a heater with a car battery?

Power inverter dc to ac

In addition to matching the voltage of the power supply (the car battery) and the device (the heater), you also need to align the type of electrical current of both. Car batteries produce DC electrical energy or direct current, while your electric heater requires AC electrical energy or an alternating current. This is why you need an inverter.

An inverter is an electronic device that converts the DC electrical energy from a power source like your car battery into AC electrical energy that your electric heater can use.

Modern inverters also function as transformers. This is a better option to reduce the number of devices you need to bring. Moreover, this is also a cheaper option since you only need to pay for one device instead of two.

300W Power Inverter DC 12V to 110V AC is available on Amazon through this link.

How to connect a transformer/inverter to a car battery

Electrical Long Extension cable cord on reel with remote socket outdoor

If you connect your heater to your car battery, you will need decent cables to run from your car to your tent. Ideally, you should connect the inverter/transformer to the car battery and then leave it inside your vehicle.

Alternatively, you can connect them to the auxiliary power port inside your car. A word of caution is that most modern auxiliary power port doesn’t have robust wiring. Connecting an inverter/transformer to power an electric heater might trip the fuse.

So, you might be better off connecting the inverter and transformer directly to the car battery.

Once the inverter/transformer is set up, connect a long, heavy-duty power cable inside your car to your tent. The power cable should be robust enough to withstand the cold weather outside your tent. There are power cables that are made for outdoor use.

Alternatively, you can pick up an extension cord that is made for outdoor use to bridge the inverter inside your car and your electric heater. Your electric heater might have its own power cable; all it needs is an extension to connect it to your inverter/transformer.

Southwire 100-foot extension cord is available on Amazon through this link.

How to supplement your car battery

Electric heaters consume a lot of electrical energy. This can quickly finish the charge of your car battery, making it impossible to start your car unless you have a dedicated car battery for your heater that your alternator also charges.

However, for your car battery to constantly get a charge from your alternator, you need to leave your car running. This can consume a lot of fuel, and you might only have enough to last your trip if you bring a lot of extra fuel.

Bringing extra fuel, however, is heavy and takes up a lot of space. An alternative is to get a portable solar power station with you. The solar panels are foldable, making them easy to bring on a camping trip.

Jackery Explorer 500 poratble battery with solar panel

Moreover, some models include their inverter/transformer. Thus, you don’t have to worry about using it to power your camp's electric heater and other electronic devices.

OUPES 600W Portable Power Station, Solar Generator is available on Amazon through this link.


You will need an inverter and a transformer to convert the electrical power from your car battery to a type that can power your electric heater.

If you enjoyed reading this article, you might find the articles below equally enjoyable to read:

Do Electric Heaters Cause Condensation?

Will A 220 Baseboard Heater Run On 110?

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