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What Is a Car Power Inverter?

Nathaniel P. Miller
Nathaniel P. Miller

A car power inverter is a small electronic device that is designed to convert the direct current electrical output from an automotive battery into an alternating current, which can be used to power things like cell phones and other small devices. Most inverters are designed to fit into a car’s cigarette lighter, which sits on the control console in most vehicles and provides easy access to battery power. The inverters in turn are normally connected to charging cords or cables designed for specific devices, particularly phones or small computers. Theoretically, almost any device can be powered from the car battery, but most inverters are intended only for small and occasional usage; powering large devices or using charges for extended periods can drain the battery and impact the power that the car itself is receiving. Larger and more permanent options may be fitted directly to the battery itself and wired into the car, though this often requires a lot of expertise.

Car Powering Basics

Power inverter with 12v car plug.
Power inverter with 12v car plug.

The batteries in most cars and trucks supply power to the vehicle generally, as well as supporting accessories like radio and lighting. When the car is driving, the battery normally charges itself, which allows for a more or less constant stream of power in the vehicle. This power comes as a direct current, or “DC.” Direct current is perfect for devices that are powered directly from the battery, but doesn’t normally work for outside electronics. Things like smartphones and music players normally require an alternating current, or “AC.” The main job of the inverter is to convert the DC signal to an AC output.

Basic Concept and Main Goals

Power inverters are sometimes installed in police cruisers to allow constant laptop access.
Power inverters are sometimes installed in police cruisers to allow constant laptop access.

People often find themselves in situations where it would be advantageous to charge various electronic devices while driving. Cell phones are a very common example, as are portable global positioning system (GPS) units. Especially on longer trips, it can be useful to be able to keep these sorts of devices fully charged. Power inverters are designed specifically for this purpose, and essentially allow a person to turn the car’s existing DC socket into an AC outlet. Once inverted the socket will work much the same as any wall outlet in a home or office, though in most cases the cords attached are device-specific.

Available Sizes

The car battery provides power for all of the electrical accessories of a car.
The car battery provides power for all of the electrical accessories of a car.

Power inverters come in a variety of sizes. Some versions simply involve plugging a cord into the cigarette lighter in the car, while permanent units are mounted in the engine compartment of the vehicle and connected directly to the battery. Most people are familiar with the cigarette lighter style of inverter, as these are relatively inexpensive, widely available in most places, and generally pretty simple to use. Many smaller appliances, such as laptop computers, DVD players, and small televisions, will run off of this style of inverter. Larger, under-the-hood inverters are mounted near the battery of a vehicle and are designed for much larger products, such as circular saws, drills, and flood lights.

A car power inverter may plug into a vehicle's cigarette lighter.
A car power inverter may plug into a vehicle's cigarette lighter.

The most advanced examples are very elaborate, often incorporating numerous outlets; others are quite simple, with just a single electric outlet or USB port. Many families install a temporary car power inverter to power a TV or DVD player for their children, for example, as they head out on cross-country road trips. Some police cruisers have permanent power inverters installed so that laptops can be run for an entire shift without concern for battery life.

Load Considerations

It is important to choose an inverter that fits both the needs of the user and the electrical demands that will be placed on it. Using a small inverter to run equipment that requires a lot of power will make it difficult to run the accessories, for instance, as most inverters have fuses that will trip over a certain voltage. To purchase the correct size inverter, the user should add up the maximum wattage for each accessory he or she plans on running simultaneously on the inverter, and then adding 10% to that number. An inverter that can handle this wattage should work without tripping the fuse while appliances are running.

There are usually many different options available, some of which tend to be better made and safer than others. People interested in purchasing inverters are usually wise to do a bit of research, particularly if they intend to rely on the availability of dependable power. A badly made or incorrectly wired inverter can damage the device into which it’s plugged, the car, or both.

Discussion Comments

Rorence

Last year, I bought a 400w power inverter from bestek for short distances trip since I need to charge my camera and laptop in the car. A friend recommended this tool to me. Even I have learned how to use this tool, but actually to say that before buying this tool, I had no knowledge about car power inverters. Thanks for you article to teach me what is a car power inverter.

Georgesplane

@ Amphibious54- I second your opinion about a power inverter being a great purchase. I work on the road, so it helps to be able to charge my phone and run my laptop. A piece of advice to anyone thinking about getting one, make sure you don't cover your inverter with clothes or anything else. It can make your inverter overheat; causing damage to your inverter or your electronics.

They also say to unplug them when the car is not running because they can drain our battery, or overheat. Some of the inverters on the market are fused and will automatically turn off when your car shuts down, but I think it’s still better to be safe and unplug them.

Amphibious54

I bought a 300 watt power inverter for a trip across country and it was one of the best purchases I made for the trip. I drove across country with my fiancée, and we didn't always stay in a hotel; occasionally opting for a camp site, and even getting stranded in a Wal-Mart parking lot. Having a power inverter allowed us to watch movies on the laptop, post pictures to the internet, and blog about our trip (we did have a wireless internet card).

We were also able to charge our phones, keep all of our camera batteries charged, and even use our stick blender for drinks at our campsite. I didn't even think I would need the inverter at first, but without it I don't think our trip would have been as fun. We still use it whenever we take road trips or head to the beach.

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    • Power inverter with 12v car plug.
      Power inverter with 12v car plug.
    • Power inverters are sometimes installed in police cruisers to allow constant laptop access.
      By: mario beauregard
      Power inverters are sometimes installed in police cruisers to allow constant laptop access.
    • The car battery provides power for all of the electrical accessories of a car.
      By: Željko Radojko
      The car battery provides power for all of the electrical accessories of a car.
    • A car power inverter may plug into a vehicle's cigarette lighter.
      By: aris sanjaya
      A car power inverter may plug into a vehicle's cigarette lighter.