How Are Cigarette Lighters and Accessory Sockets Different?

Does the difference really matter?

There was a time, not so long ago, when any barrel-shaped socket located in the vicinity of a car's dashboard was understood to be a cigarette lighter. Sure, you could use that cigarette lighter socket to power your electronics, but that didn't change what it was.

Then dedicated accessory sockets showed up on the scene, and all of that went out the window. These 12V accessory sockets look like cigarette lighter sockets, but they aren't, and the differences are important.

Cigarette lighter sockets in a car dashboard.

Car Culture Collection / Getty Images

Accessory Sockets Aren't Cigarette Lighters

After decades of cigarette lighter sockets playing double-duty as accessory sockets, it's only natural to wonder what, if any, difference there is between these two components. While this might seem complex, it's not. In basic terms, cigarette lighter sockets are accessory sockets, but accessory sockets aren't necessarily cigarette lighter sockets.

Here's the thing: There are two slightly different standards for these sockets, and while both work with 12V plugs, receptacles that meet the newer of the two standards will not accept cigarette lighters.

Further clouding the issue is that some vehicles ship from the factory with a plug in the cigarette lighter socket. That may seem to indicate that it isn't a cigarette lighter, but that isn't the case. When one of these sockets is located in the dash, and there isn't a second one clearly marked as an accessory socket, chances are it's probably a cigarette lighter socket that didn't come with the lighter portion.

Cigarette Lighters vs. Accessory Sockets

The crux of the issue here is that cigarette lighters weren't originally designed to provide power to accessories. The first cigarette lighters in cars weren't suited to that purpose. These early lighters used a "coil and reel" system, and it wasn't until "wireless" lighters appeared on the market that cigarette lighters gained the dual purpose that they enjoy today.

Because cigarette lighter sockets weren't designed to provide accessory power, they aren't well suited to the purpose. The purpose that they are suited to, which is heating a bimetallic coil until it's cherry red, is the exact opposite of what you'd like to see out of an efficient power transfer system.

The upshot is that since cigarette lighters are designed to get incredibly hot, it doesn't matter that their basic design provides a less-than-ideal electrical connection.

When Cigarette Lighter Sockets Became Something More

There are a handful of cigarette lighter standards globally, but the one used in the United States is ANSI/SAE J563. Since this standard describes measurements like the diameter of the receptacle, accessory manufacturers can make power plugs that have a relatively snug fit, and spring-loaded contacts take up the slack.

However, the standard also includes a second set of measurements that automakers can use for dedicated accessory sockets. Sockets that conform to this standard are slightly different in that they won't accept cigarette lighters but will accept 12v power plugs from chargers, inverters, and other devices.

Is It a Cigarette Lighter Socket or 12V Accessory Socket?

Unless you want to look up the specs and get out a micrometer, the best way to find out whether you're dealing with a cigarette lighter socket or an accessory socket is to check the owner's manual or contact the dealership. The two look slightly different, but it's a difference measured in millimeters.

You also can't tell whether a socket is designed to work with a cigarette lighter based on the fact that it didn't come with one. While most dash-mounted sockets are still designed to accept cigarette lighters, you shouldn't just assume that it does.

The general rule of thumb is that if your dash has multiple sockets, one of them will usually be a cigarette lighter, and the others will probably be accessory sockets. In that same vein, additional sockets located under the dash, in the center console, and elsewhere in the vehicle are usually dedicated accessory sockets. However, it's a bad idea to stick a cigarette lighter into any receptacle based on a rule of thumb. The only way to know for certain is to check with your local dealer or the manufacturer.

Does the Difference Really Matter?

In terms of powering accessories and devices, like your cellphone, there is functionally no difference between cigarette lighter sockets and accessory sockets. If you aren't sure which one you're dealing with, plug into any or all of them to suit your power requirements.

The only important difference is that you can't, or at least shouldn't, plug a cigarette lighter into an accessory socket. In the best-case scenario, nothing will happen. In a worst-case scenario, the lighter will heat up, but the socket won't be able to withstand the extreme heat of the lighter.

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