Installing additional equipment in the car often rests on the banal problem of finding a connection point. Many car owners prefer to use a regular outlet known as a “lighter” to power DVRs, radar detectors or GPS trackers. However, when trying to make an adapter yourself or replace a burned fuse in the adapter wire, a critical question arises about polarity.
Incorrect identification of contacts can lead to instant failure of expensive electronics. In the on-board network of the car is used direct-current with a voltage of 12 volts, where to confuse plus and minus is to arrange a short circuit. To avoid smoke from under the hood and burnt fuses, it is necessary to clearly understand the device of a standard car connector.
In this article, we will analyze the anatomy of the plug, methods of checking with a multimeter and the nuances of connecting various devices. You will learn how to safely extract the central contact, where to look for mass and why in some machines the voltage in the socket appears only after turning the key in the ignition lock.
Standard circuit of the car connector 12B
The car connector, which we used to call a lighter, has a unified design, adopted by most of the world's automakers. The central pin inside the nest is always a positive pole, that is, the "plusly". It is to him that the voltage from the battery is brought through the fuse. The side lobes located along the inner perimeter of the cylinder are connected to the car body and are a negative pole or "minus".
When you insert the plug into the socket, the central spring or contact at the end of the plug comes into contact with the plus five inside the socket. The lateral spring-loaded legs of the plug are pressed against the walls of the cylinder, providing contact with the mass. This design is not chosen by chance: it minimizes the risk of accidental circuit, since it requires simultaneously closing the center and sidewall, which is structurally difficult to do with your fingers.
However, there are nuances depending on the manufacturer of accessories. In cheap Chinese adapters, the labeling of wires inside the cable may not match the generally accepted color standards. Red wire usually means plus and black wire means minus, but you can’t rely on the color of the insulation alone. Instrumental verification is always required before the first switching on.
Always check polarity with a multimeter even on new devices, as budget electronics manufacturers often ignore the color marking of wires.
Instrumental verification of multimeter
The most reliable way to determine where the plus and where the minus in the plug or socket is using a digital multimeter. Before you start measuring, make sure the instrument is switched to DCV mode, usually a sector with an icon. V= or V⎓. The limit of measurement should be set to a value above 12 volts, optimally - 20V.
To check the nest in the car insert the multimeter probes inside. Press the black probe against the side wall of the cylinder (to the springy antennae, if they are inside, or to the wall itself), and the red one gently touch the central pen at the bottom. If the display displays a value of about 12-14 volts without a minus sign, then the polarity is determined correctly: the center is a plus, the sidewall is a minus.
If you check the plug itself with the wires, the process is similar. Include the multimeter in the vertebrae mode (the speaker icon) or resistance measurements. Touch one probe of the central contact of the plug, and the other - the wire, presumably being a plus. The presence of an audible signal or close to zero resistance will confirm the correctness of guesses. A similar procedure is carried out for the side contacts of the plug and the second wire.
- 🔋 Make sure that the multimeter probes are serviceable and do not have insulation damage before working with the onboard network.
- 🔌 When checking the plug without connecting to the car, use a battery or power supply to simulate the circuit if you need to check the integrity.
- ⚡ Do not touch each other’s metal parts during voltage measurements to avoid short circuits.
The process of dismantling and soldering the plug
If you need to replace the cable or solder a new connector, it is important to be careful when disassembling. A standard plug usually consists of a plastic or metal case that is unscrewed or cracked. Inside you will see two main contacts: the central, to which the plus wire is soldered, and the lateral (often in the form of a chomutic or spring), to which the minus goes.
Use it when soldering. rosin And solder with a melting point of not more than 250 degrees Celsius, so as not to melt the plastic insulator inside the plug. Clean the ends of the wires by 5-7 millimeters. The plus wire (usually red) is soldered to the central contact, which, when assembled, goes deep into the nest. The negative wire (black) is soldered to the side contact or the pressing plate.
⚠️ Attention! Before assembling the plug, be sure to check whether the cleaned wires close the wires to the side walls of the case. This will cause the fuse to burn immediately after inserting into the socket.
Assembly is made in reverse sequence, making sure that the wires inside the body are laid compactly and not clamped with the lid. If a fuse is built into the plug, make sure it sits tightly in its nest and has good contact. The fuse value is usually 10A or 15A, as indicated on the element itself or in the device instruction.
☑️ Ignition of the lighter plug
Nuances of connection of video recorders and radars
Modern DVRs and radar detectors are often equipped with cables with a ready plug. However, when installed in a hidden way ("stretching"), users cut the plug and solder the wires directly to the wiring of the car or to the fuse block. In this case, it is critical to know that for most recorders, the plus must be “cooked” only when the ignition is turned on so that the device shuts down with the car.
If you connect the recorder to a permanent plus (for example, from the battery or constant contact in the mounting unit), it will work even when the car is parked. It'll lead to a deep one. battery-rate overnight. Therefore, when connecting on your own, look for a circuit in which the voltage appears only after turning the key to the ACC or ON position.
For devices with parking recording function (parktronics, standby shock sensor) it is the constant power supply that is required. In such cases, manufacturers provide a built-in power controller or battery, but if you do the wiring yourself, take this into account. The minus in any case is taken from the body of the car, preferably at the same point where the mounting unit itself is powered.
Why is the plug warming up?
The plug may be heated due to poor contact inside the socket (weakened side petals) or due to oxidation of the contacts. Heating also causes the use of too thin wire that can not cope with the current of the load, especially for powerful compressors or refrigerators.
Typical errors and their consequences
One of the most common mistakes is to ignore the quality of the insulation. Vibrations when moving the car gradually rub the insulation of the wires, which can lead to a circuit on the mass. If the plus closes on the body to the fuse, this will cause heating of the wiring and potential fire. If after the fuse - just burn the fuse, which is a standard protective reaction.
Another mistake is to use twists instead of soldering or quality terminals. The twists in car conditions oxidize much faster than in static home wiring. Contact resistance grows, the twisting site begins to warm, melt the insulation and eventually can become a source of fire. To connect the wires, use soldering with subsequent insulation with thermal shrinkage or special crimping terminals.
Also often there is the installation of a fuse too large in denomination "so as not to burn out." This is a fatal mistake. If the device consumes 2A, and you set the fuse on 30A, then with a short circuit, not the fuse will burn, but the wiring of the device or car itself. The nominal value of the fuse should be 10-20% higher than the maximum current consumption of the device.
Using a fuse of the correct denomination is the only way to protect the wiring of the car from fire when short circuit in the connected device.
Table of correspondence of contacts and colors
For ease of perception, we will summarize the basic data on color marking and the appointment of contacts in a standard table. Remember that standards can vary, so the table serves as a reference material, not an absolute truth.
| Element | Color of wire (standard) | Function | Location in the plug |
|---|---|---|---|
| Plus contact | Red. | Food (+12V) | Central pin/spring |
| Minus contact | Black. | Mass (GND) | Side petals/hull |
| Dop. wire (light) | Blue/White | Indication of inclusion | Rarely, it depends on the model. |
| Safety lock | Transparent/Colorful | Chain protection | Inside the plug, on the plus. |
In conclusion, it is worth noting that working with the on-board network of the car requires care, but it is quite accessible to any motorist with a minimum set of tools. The main rule of the electrician: seven times to measure (check multimeter), once solder. Observing polarity and using quality materials will ensure a long life for both your gadgets and the electrical wiring of the car.
Can I charge my phone in a lighter with the engine shut down?
Yes, you can, but it is not recommended to do it for a long time. If your car socket is powered directly from the battery (permanent plus), then charging the phone will discharge the battery. Modern phones consume a little, but left overnight to charge a phone can land the battery at zero, especially if it is old or weak.
Why does the plug fall out of the lighter on the bumps?
This is due to the weakening of the side spring contacts inside the socket itself in the car or on the plug itself. Over time, the metal gets tired and unwinds. Solution: gently bend the side antennae on the plug with passages (with power off!) or replace the lighter socket itself.
What is the maximum current of a standard lighter?
A standard car lighter is usually designed for currents up to 10-15 Amps. This corresponds to a power of about 120-180 watts. Connecting powerful inverters or two compressors simultaneously through a tee can cause wiring to overheat and the contacts to melt.
What to do if there is no tension in the lighter?
First, check the safety lock. It can be found not only in the plug itself, but also in the mounting unit of the car (usually referred to as CIG or ACC). If the fuses are intact, it may have oxidized the contacts inside the socket or interrupted the wire going to the back of the socket.