Do I need to worry that it's a power outlet disguised as a cigarette lighter?

Power for mobile electronics is typically supplied through a 12V socket, also known as a car cigarette lighter or 12V auxiliary power outlet, in a variety of vehicles, including cars, trucks, RVs, boats, and a few other settings. Even though these plugs were initially intended to be used with cigarette lighters, they have become the standard for powering electronics in cars.

The same socket that was once only used as a car cigarette lighter can now power everything from a cutting-edge phone or tablet to a tire compressor.

Although it is unusual to find more than one cigarette lighter socket in a vehicle, some models do come equipped with multiple sockets specifically for this purpose.

Therefore, ANSI/SAE J563 includes two variants of these power sockets: one that is compatible with cigarette lighters and one that is not. That's why, if you've ever tried to insert a cigarette lighter into a cigarette lighter socket, the lighter has popped right back out.

There was no such thing as an automotive electrical system back in the early days of automobile use. First-generation automobiles lacked even basic electrical components. These automobiles' engines used magnetos to generate a spark, much like your modern lawnmower's, negating the need for a battery. No electrical system was needed for the occasional gas or kerosene lamp used for illumination.

Once DC generators were available, they were installed in cars to power electrical systems. In contrast to modern alternators, these devices did not need an external voltage source in order to function. They were belt-driven like modern alternators and supplied the DC current used by things like lights and other conveniences.

The next step was to install lead-acid batteries, which not only keep the lights on when the engine is off, but also provide power in emergencies. This modification paved the way for the installation of other features that are now considered standard, such as electric starter motors.

Even though early electrical systems, which relied on a DC generator and a lead-acid battery, technically allowed for electrical accessories, the widely variable voltage produced by these generators caused problems. Alternators ushered in the era of truly modern automotive electrical systems, although mechanical devices were used to control the voltage.

To charge the battery and power the vehicle's accessories, modern vehicles use alternators instead of generators, which produce direct current. The rise of the cigarette lighter as the standard DC power outlet in automobiles is in large part due to the reliability of this type of electrical system, which maintains a relatively constant voltage output regardless of the speed at which the alternator is spinning.

Even though people have been using their cars to power accessories since the invention of automotive electrical systems, those accessories had to be hardwired in. A 12V automotive electrical socket almost happened by accident because it was appropriated for another use.

In the early 1920s, cigarette lighters joined other electrical accessories like lights and radios as factory installed features in automobiles.

Although "coil and reel" cigarette lighters were common in the beginning, the "wireless" cigarette lighter eventually replaced them as the standard in cars and boats.

A cylindrical receptacle, typically mounted in the dashboard, and a detachable plug make up these "wireless" cigarette lighters for automobiles. The plug has a coiled bimetallic strip that connects to the receptacle's power and ground contacts.

Electrical current flows through the coiled strip when the plug is inserted into the receptacle. To light a cigar or cigarette, simply pull the plug out of the outlet and use the red-hot coil.

While cigarette lighters in cars weren't necessarily made with accessory power in mind, the opportunity was too good to pass up. The receptacle made it simple to connect to power and ground once the coil-and-reel lighter was no longer in use, as the lighter part was detachable.

Because of this, a power plug was developed so that automotive accessories could be easily plugged in and out of the car's electrical system with no need for permanent wiring.

Cigarette lighter receptacles and 12V power plugs from different manufacturers must adhere to the ANSI/SAE J563 standard for interoperability. The cylinder of a 12V socket must be connected to ground (the negative terminal) and the center contact to the positive terminal, as specified by the standard.

With the ANSI/SAW standard in place, manufacturers of everything from tire pumps to hairdryers could create and market products that could be powered by cigarette lighter plugs.  

There are a few problems with using a car's cigarette lighter as an accessory socket because it was not designed for that purpose. Therefore, 12V socket-compatible devices must be able to compensate for these drawbacks.

The inner diameter and depth of a cigarette lighter receptacle pose the greatest challenge when used as a 12V socket in a vehicle. Most 12V power plugs have spring-loaded contacts to accommodate the size differences between these receptacles, also known as cans.

Electrical contact in 12V power plugs is maintained over a wide range of variations thanks to their spring-loaded contacts. That said, it also means that there's a chance that this plug type could experience intermittent electrical contact loss.

Another problem that arises from plugging something into a car's 12V socket is that of the specifics of car electrical systems. Normal operation allows for a range of output voltages, even though modern alternators are capable of maintaining a relatively uniform voltage output.

Accordingly, all auto electrical accessories must be able to function on a DC voltage range of 9-14 volts. Commonly, a DC-to-DC converter is integrated into the device to instantly transform the fluctuating input voltage into a stable output voltage.

The use of cigarette lighters in vehicles is declining along with the overall popularity of smoking, but it shows no signs of stopping anytime soon. The idea of eliminating the cigarette lighter from cars hasn't caught on, despite the fact that some vehicles have been sold without one and others have included an accessory socket with a blank plug in its place.

Problems arise because even if people aren't using cigarette lighters in cars for their intended purpose, far too many portable devices rely on the technology as a de facto power source for us to abandon it entirely.

The widespread adoption of USB for data and power in portable devices suggests that it could be a viable alternative. Even though it's simple to connect a USB charger to a car's cigarette lighter, automakers may be slow to fully embrace USB ports as a replacement for cigarette lighters and accessory plugs.