A DC connector (or DC plug, for one common type) is an electrical connector that supplies direct current (DC) power.
Compared to domestic AC power plugs and sockets, DC connectors have many more standard types that are not interchangeable. The dimensions and arrangement of DC connectors can be chosen to prevent accidental interconnection of incompatible sources and loads. Types vary from small coaxial connectors used to power portable electronic devices from AC adapters to connectors used for automotive accessories and for battery packs in portable equipment.
Extra-low voltage (under 120 VDC) These extra-low voltage connectors are rated at or below 120 VDC.
Cylindrical connectors
Small cylindrical connectors come in various sizes. They may be known as "coaxial power connectors," "barrel connectors," "concentric barrel connectors," or "tip connectors."
These plugs are intended for use on the cable connected to an external AC adapter (power supply). The matching jack or socket is permanently fitted to power the equipment. Some of these jacks contain a normally closed contact, which can be used to disconnect internal batteries whenever the power supply is connected, avoiding the risk of battery leakage or explosion posed by incorrect battery recharging.
Cylindrical plugs usually have an insulated tip constructed to accept the insertion of a pin. The outer body of the plug is one contact, most often but not always the negative side of the supply. Inverted polarity plugs can and do damage circuitry when plugged in, even if the voltage is correct; not all equipment is equipped with protection. A pin mounted in the socket makes contact with a second internal contact. The outer plug contact is often called the barrel, sleeve, or ring, while the inner is called the tip.
There are a wide variety of sizes and designs for these power connectors, and many appear pretty similar to each other yet are not quite mechanically or electrically compatible. In addition to many generic designs (whose original designer is unknown), there are at least two national standards—EIAJ in Japan and DIN in Germany, plus the JSBP connector used on some laptop computers. The Japanese EIAJ standard includes five sizes, each supporting a specified range of voltages. However, most other coaxial DC power connectors have no specified voltage association. Generic plugs are often named for the pin diameter they are designed to take.
Many non-proprietary co-axial power plugs are in outside diameter (OD) and in length. Two pin sizes are standard in the jacks for this size plug body, and , and the plugs should match. If the size is not known, it is difficult to distinguish by eye or measurement between the 2.1mm and 2.5mm ID plugs; some suppliers suggest simple methods.
Maximum current ratings commonly vary from unspecified up to 5 A (11 A for unique high-power versions from some companies), with 1 A, 2 A, and 5 A being common values. The smaller types usually have lower ratings, both for current and voltage. The 'tip' (i.e., the inner conductor) usually carries the positive (+) pole, but some devices and their power supplies use the negative tip. The connector size does not usually indicate the voltage. It is not possible, except for some proprietary connectors, to reliably infer any information on power parameters (current, voltage, polarity, even whether AC or DC) by examining the connector.
Snap and lock DC power connectors
Snap and lock DC power connectors look similar to Mini-DIN connectors but have either 3 or 4 thicker pins and a slightly larger mating shell. Because of this, they do not mate with any of the standardized Mini-DIN connectors. Some devices, however, use a proper 4-pin Mini-DIN connector for power instead, presenting the possibility of mating such a connector with the wrong port (such as an S-Video output). Known as Kycon 3-pin and 4-pin DC power plugs. Erroneously also known as "Power DIN", although different from any standardized Mini-DIN or DIN connector type. The male plug's mating shell outer diameter is , and the pins are diameter Standard may include a limit of 20 V at 7.5 amperes Sometimes, there's a knurled retaining ring surrounding the male plug which allows fastening the plug to the chassis receiving the power. Some connectors have a right-angle connector, as seen in the picture. For aesthetics, some Dell laptop chargers have a glowing ring at the connector tip.
Molex connector
Molex connectors were frequently used as DC power connectors in personal computers, for floppy, hard disk, and CD drives. These connectors have four pins, +5 V (red), 2 common ground (black), and +12 V (yellow). SATA peripherals use a different style of connector.
Locking Molex connectors are available in 3, 4, and 6 terminal configurations.
XT connectors Solder cup terminals are primarily designed for the in-line solder termination of conductors. This style of terminal is principally designed as a precision-machined pin for insertion into connector bodies.
IEC 60906-3:1994 The International Electrotechnical Commission (IEC) has produced a standard for a system of 2-pin plugs and socket-outlets for household and similar purposes in fixed and portable applications, either indoors or outdoors. Safety extra-low voltage (SELV) plugs and socket-outlets carry up to 16 amperes, and have eight keying possibilities, to indicate 6, 12, 24, or 48 volts, AC or DC.
The connector is circular, with the male connector having two pins placed symmetrically inside a circular shield, and the female connector having two receptacles surrounded by a circular groove to accept the male shield, in turn surrounded by a second circular shield which projects past the mating surface and encloses the male connector. (It somewhat resembles a smaller IEC 60309 connector.)
The dimensions are as follows: Parameter Value Pin-to-pin distance Pin diameter () Pin length (ref) Female pin receptacle Female body diameter Female groove depth Male shield inner diameter () Male shield length () Male pin tip to shield tip Male shield outer diameter Female shield inner diameter Female shield length
The male shield has two keys projecting inwards, which fit into notches in the female body. The larger key is at right angles to the pins, wide and ending at a radius of from the connector centre. The corresponding notch is wide and ends at a radius of from the connector centre.
The angle of the second key from the first indicates the voltage and current type. The eight permitted angles are multiples of 30° which are not multiples of 90°. Angles of ±30° and ±60° indicate alternating current (50 or 60 Hz), while angles of ±120° or ±150° indicate direct current with the pin at 90° being negative and the pin at 270° being positive.
The second key is smaller than the first, wide ending at a radius of from the connector centre. The corresponding notch in the female connector body is wide and ends at a radius of from the connector centre.
With the angles measured clockwise looking at the female connector (counter-clockwise looking at the male), the various key positions indicate: Angle Supply 30° 6 V AC 60° 12 V AC 120° 6 V DC 150° 12 V DC 210° 24 V DC 240° 48 V DC 300° 24 V AC 330° 48 V AC
The so-called "Mini IEC connectors" are unrelated and not even standardized by the IEC at all; they are called that because they resemble a smaller IEC C13 connector.
IEC 61076 (ELV)
The International Electrotechnical Commission (IEC) has standardized a set of multi-pin screw plugs matching ISO metric screw thread, available in M5, M8 and M12 sizes. M5 connectors are very low current, typically only used for signal wiring, while some M8 pin arrangements are rated for up to 3 A, and some M12 arrangements are available up to 16 A. The multi-pin design caters for Ethernet, single and three-phase AC, as well as single or multiple voltage DC. The DC ratings are typically 60 V and below, however the F-coding is rated for 300 V (see #IEC 61076 (LV) below).
Tamiya connectors
Tamiya connectors are commonly used on radio control (toy) vehicle battery packs and chargers.
JST RCY connector
The JST RCY-series connector is a 2.5mm-pitch and manufactured by J.S.T. Mfg. Co., Ltd. It is known in radio control circles as the battery eliminator circuit (BEC) or P connector. JST also produces other types of connectors that are used in R/C and hobby electronics.
Deans style T-Plug
The Deans style T-Plug connector is a polarized high power plug that inhibits accidental reversed connections. This also applies in particular to avoid the LiPo flash, which can cause burn injuries or related damage. Depending on the make, Deans plugs are sensitive to overheating during soldering, as the plastic can become soft and the plug surfaces can easily twist. Depending on the construction, they can support currents up to 40A (pulse to 70A).
Usual pin assignment T-Plug: negative (-) is the parallel pin; positive (+) is the perpendicular pin.
Inverter tabs/lugs
Inverter tabs/lugs are available in 2, 4, and 8 AWG. These are designed to pass very high currents at voltages up to 600 V DC to and from battery packs, inverters, and other high-current loads to a terminal bus.
Airline in-seat power supply system
Two different airline in-seat power supply system (ISPSS) standards for DC power have been used in the past. American Airlines in the past used an automobile auxiliary power outlet. Most other airlines that provide DC power use the smaller EmPower system, which has a 4-pin Hypertronics' D-series connector. It can supply 15 volts maximum 5 amperes.
Anderson Powerpole connectors
Powerpole connectors are a series developed by Anderson Power Products and available in a variety of sizes and colors. The commonly used 15/30/45 series connectors are interoperable and use the same housings but different contacts for different wire sizes and current requirements.
Powerpole connectors are physically and electrically genderless, thus avoiding the need to worry about which end is the plug and which the socket, or which end has the correct polarity, as is the case with the physically but not electrically genderless two-wire trailer plug.
Powerpoles have been adopted as a standard 12 VDC connector by most RACES Radio Amateur Civil Emergency Service organizations and ARES Amateur Radio Emergency Service units. They deliver good current capability for their sizes and facilitate very easy pluggability for those without good eyesight or good lighting. However, they can be damaged relatively quickly and, if not correctly crimped, can occasionally separate from each other easily with minimal force unless additional retaining measures are taken.
SAE connector
The SAE connector is a physically self-mating hermaphrodite two-conductor DC connector commonly used for solar and automotive applications (including motorcycles). It is so named for the Society of Automotive Engineers which created the specifications this connector is based on.
Although the plug is physically hermaphroditic, and any SAE connector can be connected to any other SAE connector, they are NOT electrically hermaphroditic, and care needs to be taken to maintain correct polarity when connecting different plugs.
This connector typically applies a maintenance charge to a vehicle battery. When installed in a vehicle and attached to a battery, the polarity of the connector is always such that no short circuit will occur if the exposed terminal touches the vehicle chassis. In most vehicles, this means that the exposed terminal connects to the battery's negative terminal. Conversely, the positive terminal on a battery charger is exposed to mate with the concealed one on the vehicle side. (This is reversed on vehicles with a positive-ground frame, such as vintage British motorcycles.)