How A Car Power Adapter Can Run Your Electronics

In-car power for all your devices and gadgets

Depending on how much time you spend in your car on a daily basis, there are a lot of different types of electronics that you might want to be able to use on the road. Entertainment devices, like CD and MP3 players, GPS navigation units, and even DVD players can all be run off of 12 volts, but finding the correct car power adapter is only one of the factors that you need to consider before you start plugging in.

First, it’s important to understand the basics of your car’s electrical system. For instance, the electrical system in your car, in most cases, provides 12V DC, which is quite different from the AC power you use at home.

With that in mind, it’s also essential to understand that you have two main options for powering devices in a car: you can buy a 12V accessory outlet or cigarette lighter, or install a power inverter.

Within those constraints, the primary methods of using 12-volt car power to run your electronic devices on the road include:

Person using laptop connected to car power.camping laptop.
Matthew Micah Wright / Lonely Planet Images / Getty

Using 12V DC Outlets to Power Electronics

The easiest way to power an electronic device in your car is via the cigarette lighter receptacle or a dedicated 12V accessory outlet, which are the two types of 12V sockets you can find in virtually every modern car and truck.

As the name implies, these sockets started out as cigarette lighters, which worked by applying current to a coiled metal strip. This current flow would cause the coiled metal strip to become red hot — hot enough, in fact, to light a cigarette on contact.

It didn’t take too long for inventive minds to find another use for cigarette lighter sockets, which are now also known as 12V accessory outlets. Since the sockets apply battery voltage to the center contact and ground to the cylinder, according to ANSI/SAE J563 specifications, 12V devices can be powered by a plug that makes electrical contact with those two points.

The standards are a little different from one part of the world to another, and the specifications for a cigarette lighter socket and a 12V accessory socket aren’t precisely the same, but 12V plugs and adapters are designed to work within a range of tolerances.

Of course, fact that these sockets originated as cigarette lighters, and the corresponding sloppy tolerances, mean that there are a host of potential issues that can arise from using them as power sockets.

Today, some cars ship with a plastic plug or USB outlet in the dash outlet in lieu of the traditional cigarette lighter, and some sockets are even physically incapable of accepting cigarette lighters, often because they're too narrow in diameter or too shallow.

Plastic plugs are also available via the aftermarket for owners of older vehicles who prefer not to have a cigarette lighter in their car.

Powering Devices with Built-In 12V DC Plugs

While a cigarette lighter or 12V accessory outlet is the easiest way to power an electronic device in a car, the situation is greatly simplified if the device in question has a hard-wired 12V DC plug. These devices are specifically designed for use in cars, so you typically won’t even have to worry about power consumption or blowing fuses.

Devices that sometimes have hard-wired 12V DC plugs include:

Powering Devices with 12V DC Power Adapters

Devices that don’t have hard-wired DC plugs sometimes have 12V DC adapters or are compatible with adapters that you can buy separately. GPS navigation units, cell phones, tablets, and even laptops often fall into this category. And while you do have to be careful about how much amperage you draw with these devices, it’s still a relatively simple plug-and-play solution.

Devices that are often compatible with proprietary 12V DC adapters include:

Powering Devices with 12V USB Adapters

In the past, 12V DC adapters used a variety of incompatible plugs in addition to a wide range of voltage and amperage outputs. This was particularly true of the cellular phone industry, where two phones from the same manufacturer often required radically different DC adapters.

In recent years, many devices like phones and tablets have moved toward using the USB standard instead of proprietary connectors. That means that most modern devices can use generic 12V USB adapters for power.

Common devices that can use 12V USB adapters include:

  • Cell phones
  • Tablets
  • GPS units
  • FM broadcasters
  • Bluetooth hands-free devices

Powering Devices with 12V Car Power Inverters

Although car power inverters are more complicated to use than 12V adapters and plugs, they are also much more versatile. Since these devices convert 12V DC power to AC power and provide that electricity via a standard wall plug, they can be used to run virtually any electronic device off of car power.

Whether you want to plug in a crockpot, dry your hair, or even microwave a burrito in your car, you can do it with a car power inverter.

Of course, there are some inherent limitations involved when you’re working with car inverters. First of all, the simplest ones that plug into a cigarette lighter or 12V accessory outlet are severely limited in their utility.

Since cigarette lighters are typically wired with 10A fuses, you can’t power a device via a plug-in inverter that draws more than 10 amps. And even if you wire an inverter directly to the battery, you’re limited by the maximum output of your alternator.

If you want to run a device off of car power, and it’s not listed in any of the categories above, then a car power inverter is going to be your best bet. At that point, you’ll need to consider how much power you need and the amount of power that your electrical system is capable of putting out.

Although the power for your electronics comes from the alternator whenever your car is running, the battery is the source whenever the engine is off. So if you want to run your devices when you aren't actually driving, then you may want to consider installing a second battery. In some cases, it can even be useful to add a cutoff switch to the main battery to prevent your electronic devices from draining it down to nothing while you're parked.

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