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From Car Cigarette Lighter to 12v Accessory Socket

How did lighters turn into accessory outlets?

Also known as a car cigarette lighter or 12V auxiliary socket, the 12V outlet is the primary method of powering portable electronic devices in cars, trucks, recreational vehicles, boats and many other contexts. Although these outlets were originally designed to heat cigarette lighters, they quickly gained popularity as a de facto automotive electrical outlet.

Today, it’s possible to power anything from a high-end phone or tablet to a tire compressor with the same socket that was once used simply as a car cigarette lighter.

Some vehicles come with multiple outlets to power various accessory devices, although it is rare to be able to accept multiple cigarette lighters.

Therefore, the specifications for these sockets in the ANSI/SAE J563 standard include two variants: one with cigarette lighter and the other with non-operation. If you’ve ever tried inserting a cigarette lighter into the cigarette lighter socket so that it just falls back down, that’s why.

The history of the power of automotive accessories

When the first cars hit the roads, there was no automotive electrical system idea yet. In fact, early cars didn’t even include any kind of electrical system. These cars had engines that relied on magnetos to provide a spark, just as your lawnmower probably does today, so no batteries were needed. When lighting was included, it was done with a gas or gas lamp, so no electrical system was needed either.

When automotive electrical systems finally arrived, they used DC generators. These generators, unlike modern alternators, do not require any voltage input to operate. Like modern alternators, they were belt driven and provided the DC power needed to run accessories like lights.

The next innovation was the addition of lead-acid batteries to store electricity and provide a source when the engine is not running. With this addition, it became possible to suddenly add other accessories that we take for granted today, such as electric starters.

While early electrical systems incorporating a DC generator and a lead-acid battery made electrical accessories technically possible, the widely varying voltage produced by these generators posed problems. Mechanical devices were used to regulate voltage, but modern automotive electrical systems didn’t make it until the introduction of alternators.

Unlike generators, alternators found in modern cars and trucks produce alternating current that is converted to direct current to charge the battery and provide accessory power. Although this type of electrical system still does not provide exactly equal voltage, the voltage output remains relatively constant regardless of how fast the alternator is spinning; this was a major factor in the rise of the automobile cigarette lighter as a de facto DC power. electrical plug.

smoking gun

Although people have been powering accessory devices with automotive electrical systems since automotive electrical systems were invented, accessories had to be connected manually. The appearance of a 12V automotive power outlet was almost accidental as it was chosen for a completely different initial purpose.

Tom Blaha / Creative Commons / CC BY-SA 3.0

Along with lights and radios, lighters were among the first accessories to take advantage of early automotive electrical systems and began appearing as OEM options around 1925.

These early lighters used a “coil and reel” system, but it was the so-called “wireless” lighter that would eventually become the de facto automotive and marine electrical outlet.

These “wireless” car cigarette lighters consist of two parts: a cylindrical socket normally found on the dash of a car, and a removable plug. The outlet is connected to power and ground, and the plug contains a helical bimetallic strip.

When the plug is inserted into the socket, the spiral strip completes an electrical circuit and then becomes incandescent. When the plug is unplugged, the glowing coil can be used to light a cigar or cigarette.

Meet the 12V socket

Although not originally designed to power accessories, car cigarette lighters offered an opportunity too good to miss. The socket itself provided easy access to power and ground, as the main part of the lighter was removable when the reel and reel version fell out of use.

This easy access to power and grounding allowed the development of a pluggable electrical plug without the need for an accessory to be permanently connected to an automobile’s electrical system.

The ANSI/SAE J563 specification was developed to ensure compatibility between cigarette lighter sockets and 12V sockets from different manufacturers. According to the specification, the cylinder portion of a 12V outlet must be connected to the negative battery, which is grounded in most automotive systems, and the center contact point to the positive battery.

While the ANSI/SAW standard was in effect, third parties were able to design and bring to market a wide variety of devices, from rubber pumps designed to draw power from cigarette lighter sockets to hair dryers.

Problems using an automotive 12v socket

Since car cigarette lighters were not originally designed to be used as accessory sockets, there are some inherent problems with using this capacity. Therefore, devices designed to use 12V sockets should be able to overcome these deficiencies.

The biggest issue with using a car cigarette lighter outlet as a 12V outlet is the inside diameter and depth of the outlet itself. Because there is some variation in the size of these sockets, sometimes called boxes, 12V power plugs often have spring contacts.

By using spring contacts instead of fixed contacts, 12V power plugs can maintain electrical contact over a wide tolerance range. However, this also means that these types of plugs may lose electrical contact from time to time.

A 12V accessory plug showing spring contacts.

Tom Blaha / Creative Commons / CC BY-SA 3.0

Another issue with using a 12V automotive outlet has to do with the way automotive electrical systems work. While modern alternators are capable of maintaining a relatively uniform voltage output, normal operation allows for a range of output voltages.

With this in mind, all automotive electrical accessories should be able to operate at approximately 9-14V DC. In most cases, an integrated DC-DC converter is used to convert the variable input voltage to a constant output voltage in real time.

Can the cigarette lighter be replaced?

While smoking isn’t as popular as it used to be, car lighters aren’t likely to arrive anywhere anytime soon. Some cars have been on the market without a cigarette lighter over the years, and others have included an accessory socket with a blank plug instead of a cigarette lighter, but the idea of ​​removing the car’s cigarette lighter hasn’t caught on yet.

The thing is, even if people don’t use their car cigarette lighter for the purpose for which it was originally designed, many handheld devices rely on technology as a de facto power source to abandon it altogether.

USB can be an acceptable alternative because many portable devices use USB for data and power. It’s possible that USB ports will eventually outlast car cigarette lighter sockets and accessories, but plugging a USB charger into a car cigarette lighter is so easy that automotive manufacturers may be hesitant to fully embrace such a change.


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From Car Cigarette Lighter to 12v Accessory Socket

How cigarette lighters became accessory power outlets

The 12V socket, also known variously as a car cigarette lighter or 12V auxiliary power outlet, is the primary method by which power is delivered to portable electronics in cars, trucks, recreational vehicles, boats, and in a handful of other contexts. While these sockets were originally designed to heat up cigarette lighters, they quickly gained popularity as a de facto automotive electrical outlet.

Today it’s possible to power anything from a cutting-edge phone or tablet to a tire compressor with the same exact socket that was once used only as a car cigarette lighter.

Some vehicles come with multiple sockets for the express purpose of powering multiple accessory devices, although it is uncommon for more than one to be capable of accepting a cigarette lighter.

Accordingly, the specifications for these power sockets that are contained in ANSI/SAE J563 include two variants: one that works with cigarette lighters and one that doesn’t. If you’ve ever tried putting a cigarette lighter into a cigarette lighter socket only for it to fall right back out, that’s why.

The History of Automotive Accessory Power

When the first automobiles hit the road, the idea of an automotive electrical system didn’t exist yet. In fact, the first cars didn’t even include electrical systems of any kind. These cars had engines that relied on magnetos to provide a spark, just like your lawnmower probably does today, so no battery was necessary. When lighting was included at all, it was by way of gas or kerosene lamp, so no electrical system was required there either.

When automotive electrical systems finally did arrive, they used DC generators. These generators, unlike modern alternators, didn’t require any voltage input to operate. They were belt-driven, just like modern alternators, and they provided the necessary DC power to run accessories like lights.

The next innovation was the addition of lead-acid batteries to store electricity and provide a source when the engine wasn’t running. With this addition, it suddenly became possible to add other accessories that we take for granted today, like electric starter motors.

Although early electrical systems that included both a DC generator and a lead-acid battery technically made electrical accessories possible, the widely variable voltage produced by these generators created issues. Mechanical devices were used to regulate the voltage, but modern automotive electrical systems didn’t really arrive until the introduction of alternators.

Unlike generators, the alternators found in modern cars and trucks produce alternating current, which is converted into direct current to charge the battery and provide accessory power. Although this type of electrical system still doesn’t provide entirely uniform voltage, the voltage output does remain relatively steady regardless of how fast the alternator is spinning, which was a key factor in the rise of the car cigarette lighter as a de facto DC power outlet.

The Smoking Gun

Although people had been powering accessory devices with their automotive electrical systems ever since automotive electrical systems were first invented, accessories had to be wired in manually. The appearance of a 12V automotive electrical socket was almost accidental, as it was co-opted from a completely different initial purpose.

Tom Blaha / Creative Commons / CC BY-SA 3.0
Cigarette lighters, along with lights and radios, were among the first accessories to take advantage of early automotive electrical systems, and they started to appear as OEM options by about 1925.

These early cigarette lighters used a “coil and reel” system, but it was the so-called “wireless” cigarette lighter that would eventually become the de facto automotive and marine power socket.

These “wireless” car cigarette lighters consist of two parts: a cylindrical receptacle that’s typically located in the dash of a car and a removable plug. The receptacle is connected to power and ground, and the plug contains a coiled, bi-metallic strip.

When the plug is pushed into the receptacle, the coiled strip completes an electrical circuit and subsequently becomes red hot. When the plug is removed from the receptacle, the red-hot coil can be used to light a cigar or cigarette.

Introducing the 12V Socket

Although they weren’t originally designed with the purpose of supplying power to accessories, car cigarette lighters provided an opportunity that was simply too good to pass up. Since the actual lighter portion was removable once the coil-and-reel version fell out of use, the receptacle itself provided easy access to power and ground.

That easy access to power and ground allowed for the development of a power plug that could be inserted and removed with no need to permanently wire an accessory into the electrical system of a car.

The ANSI/SAE J563 specification was developed to ensure compatibility between cigarette lighter receptacles and 12V power plugs made by different manufacturers. According to the specification, the cylinder portion of a 12V socket has to be connected to battery negative, which is ground in most automotive systems, while the center contact point is connected to battery positive.

With the ANSI/SAW standard in place, third parties were able to design and introduce a massive range of devices, from tire pumps to hairdryers, that were designed to draw power from cigarette lighter sockets. 

Problems With Using an Automotive 12v Socket

Since car cigarette lighters weren’t originally intended for use as accessory sockets, there are a few inherent issues with using them in that capacity. Accordingly, devices that are designed to use a 12V socket have to be capable of working around these shortcomings.

The biggest issue with using a car cigarette lighter receptacle as a 12V socket is the inner diameter and depth of the receptacle itself. Since there is some variation in the size of these receptacles, which are sometimes referred to as cans, 12V power plugs typically have spring-loaded contacts.

By using spring-loaded contacts instead of fixed contacts, 12V power plugs are able to maintain electrical contact within a fairly generous range of tolerances. However, it also means that this type of plug may lose electrical contact from time to time.

Tom Blaha / Creative Commons / CC BY-SA 3.0
Another issue with using an automotive 12V socket is related to the way that automotive electrical systems work. Although modern alternators are capable of maintaining a relatively uniform voltage output, the normal operation does allow for a range of output voltages.

With that in mind, all automotive electrical accessories have to be capable of running on roughly 9-14V DC. In many cases, a built-in DC-to-DC converter is used to convert the variable input voltage to a steady output voltage on the fly.

Could the Car Cigarette Lighter Be Replaced?

Although smoking isn’t as popular as it once was, car cigarette lighters are unlikely to go anywhere anytime soon. Some cars have shipped over the years without cigarette lighters, and others have included an accessory socket with a blank plug instead of a lighter, but the idea of ditching the car cigarette lighter altogether still hasn’t caught on.

The issue is that even if people aren’t using car cigarette lighters for the purpose that they were originally designed, far too many portable devices rely on the technology as a de facto power source to ditch it altogether.

USB may prove an acceptable replacement because so many portable devices use USB for data and power. It’s feasible that USB ports could eventually overtake cigarette lighter and accessory sockets in cars, but it’s so easy to simply plug a USB charger into a car cigarette lighter that automotive manufacturers may hesitate to fully embrace that type of change.

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