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.
Cylindrical connectors 
Small cylindrical connectors come in a variety of sizes. They may be known as "coaxial power connectors", "barrel connectors", "concentric barrel connectors" or "tip connectors".
The intended use of these plugs is on the cable connected to a power supply. The matching jack or socket is then mounted in the equipment to be powered. 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 recharging of the batteries.
Cylindrical plugs generally have an insulated tip constructed to accept insertion of a pin. The outer body of the plug is one contact, most often but not always the negative side of the supply. A pin mounted in the socket makes contact with a second internal contact. The outer plug contact is often called the sleeve, while the inner one is called the tip.
There are a wide variety of sizes and designs for these power connectors, and many appear quite similar to each other yet are not quite mechanically or electrically compatible. In addition to a plethora of generic designs (whose original designer is unknown) there are at least two different national standards—EIAJ in Japan and DIN in Germany, plus the JSBP connector used on some laptop computers. The Japanese EIAJ standard includes five different sizes, with each supporting a specified range of voltages. Most of the other coaxial DC power connectors have no specified voltage association, however.
The most common plugs are 5.5 mm (0.22 in) in outside diameter (OD) and 9.5 mm (0.37 in) in length. Two pin sizes are common in the jacks for this size plug body, 2.1 mm (0.083 in) and 2.5 mm (0.098 in), and the plugs should ideally match. Generic plugs are often named for the pin diameter they are designed to take.
Contact ratings vary from unspecified (and probably less than 1 A in practice) up to 5 A, with 2 A typical. Voltage is again often unspecified, up to 48 V with 12 V typical. The smaller types usually have lower ratings, both for current and voltage. The 'tip' (i.e., the inner conductor) usually carries the positive (+) pole.
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. They can usually be identified by an engraved symbol on the backs of the plug, consisting of two wide arrows pointing in opposite directions, but parallel to each other, or sometimes one wide arrow inside a box, pointing towards the end of the male connector. Some devices, however, use a true 4-pin Mini-DIN connector for power instead, presenting the possibility to mate 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 10 mm (0.39 in), and the pins are 1.5 mm (0.059 in) diameter
- Standard may include a limit of 20 V at 7.5 amperes
- Hosiden part number TCP8927-53
- Kycon part number KPP-3P (obsolete) or KPPX-3P (RoHS)
Molex connector 
The connector design most commonly called a Molex connector has frequently been used to supply DC power, most frequently on personal computers, for supplying power to drives and other peripherals. It has four pins, +5 V (red), 2 com/ground (black), and +12 V (yellow).
Locking Molex connectors are available in 3, 4, and 6 terminal configurations.
IEC 60906-3:1994 
The International Electrotechnical Commission (IEC) has produced a standard for a system of plugs and socket-outlets for household and similar purposes in fixed and portable applications. Safety extra-low voltage (SELV) plugs and socket-outlets for 16 amps and 6, 12, 24, or 48 volts AC and DC. For use either indoors or outdoors.
The dimensions are as follows:
|Pin to pin distance||7.0 ± 0.1 mm (0.276 ± 0.004 in)|
−0.075 mm (0.1400+0
|Female sleeve||4 mm (0.16 in)|
|Pin length||10 mm (0.39 in)|
|Connector diameter||19.4 mm (0.76 in)|
There are also Mini IEC connectors.
Tamiya connectors 
Tamiya connectors are commonly used on radio-control (toy) vehicle battery packs and chargers.
Deans connectors 
Deans connectors are popular with higher-end radio-control vehicle battery packs and chargers.
JST RCY connector 
The Japan Solderless Terminal (JST) connector is also known in RC circles as the BEC connector, or the P connector. JST also produces other types of connectors that are used in RC and hobby electronics.
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 has in the past used an automotive cigar lighter socket. Most other airlines that provide DC power use the EmPower system, which has a 4-pin Hypertronics' D-series connector smaller in diameter and overall size than a cigar lighter plug. It uses 15 volts maximum 5 amperes.
Anderson Powerpole connectors 
Powerpole connectors are physically and electrically hermaphroditic, 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 hermaphroditic 2-wire trailer plug. Powerpoles have been adopted as a standard 12VDC connector by most RACES Radio Amateur Civil Emergency Service organizations and ARES Amateur Radio Emergency Service units
SAE connector 
The SAE connector is a hermaphrodite two-conductor, DC connector commonly used for automotive applications (also motorcycles). It is so named for the Society of Automotive Engineers who created its specifications.
This connector is typically used for applying a maintenance charge to a vehicle battery. The polarity of the connector, when installed in a vehicle and attached to a battery, is always such that no short circuit will occur if the exposed terminal were to touch the vehicle chassis. In most vehicles, this means that the exposed terminal connects to the negative terminal of the battery. Conversely, the positive terminal on a battery charger is exposed, to mate with the concealed one on the vehicle side.
Although there is a risk of short-circuiting a battery charger, the risk is minimal and often mitigated by the circuitry of the battery charger itself. On the other hand, the short circuit current of the lead-acid batteries installed in vehicles is sufficiently great, that a short circuit could result in a fire or explosion. The priority is therefore given to avoiding short circuits of the vehicle battery, rather than of the charger.
Cigar lighter sockets and plugs 
The car cigarette lighter socket is also called a cigar lighter receptacle, since it was originally designed as a lighter for cigars—hence its rather large size. These sockets were not originally designed to provide DC power, and are not an ideal DC connector for several reasons. Three sizes exist (one for 6 V DC and two for 12 V DC) and the mating of the different sized 12 V DC plugs and jacks is problematic. Because of this, and the small gauge wire sometimes used, they may provide unreliable power connections.
The polarity for 12 V DC sockets is center pin positive (+), outer collar negative (−). Reversed polarity will damage some electronic devices.
Although the nominal voltage of a 12 V lead acid battery is 12 volts, when the engine is running the car's battery charging system will bring the system voltage to 13.8 volts or higher. The possible range of battery voltages from 11–15 volts must be taken into account by devices attached to the cigar lighter socket.
This connector is also often used for powering accessories on motorcycles, such as heated clothing (vests, gloves, etc) or GPS units. This makes "plugging in" easier to manage while wearing gloves. As the accessory lacks any power of its own, there's no risk of "shorting" the exposed connector.
ISO 4165 connector 
Similar in concept to an automotive cigar lighter, the ISO 4165 connector is shorter and smaller, and found most frequently on motorcycles.
It is also known as "Powerlet connector", "BMW Accessory connector" or "Hella plug".
XLR connectors used for power 
In the broadcast, film and television industries, the 4-pin XLR connector is the standard for 12 V power. The connectors are wired pin 1 negative, pin 4 positive. Often pins 1 and 2 will be negative, 3 and 4 positive for a higher current rating. Female connectors are used as supply and male connectors are used on loads. Most battery belts and power supplies output 13.2 V, but equipment can usually handle a range of 11–18 volts to accommodate battery packs of varying voltages and charging while operating.
The readily available XLR3 is also used by some manufacturers as power supply plugs despite their being a well-accepted standard for other purposes.
Other DC connectors 
- There are a number of similar design PC board power connectors, including Molex Mini-Fit SR, Molex Mini-fit jr., MOLEX MICROFIT and Molex SABRE connectors, and AMP DUAC connectors that look similar to each other.
- Some plugs with three, four, five or more pins are also called DC plugs. These were common on vacuum tube equipment and continue to be used where several voltages are supplied. On vacuum tube equipment the pins are normally on the equipment side of the join for safety reasons.
- Many mobile phones use DC connectors that are unique to the manufacturer, or even a specific phone. In the interest of improved interoperability of phone battery chargers, major manufacturers have agreed to standardize on the micro-USB connector for new phone chargers from 2010.
- Many manufacturers make special-purpose DC power connectors for battery packs, instruments, medical equipment, communications equipment and other devices.
- Power Pack (PP) series of batteries such as the PP3 nine-volt battery have circular and hexagonal terminals which mate with a "snap" connector with physically identical (but opposite-polarity) terminals.
In Australia, a T-configuration Clipsal 402/32 socket is used for DC power outlets, such as in stand-alone power systems (SAPS) or on boats, in order to prevent accidental connections of 12 V appliances into 240 V socket-outlets. For this use, the horizontal slot is on top and is positive. This is also used for temporary equipment in emergency vehicles. In Victoria the top of the T is taken to look like a minus sign, and is therefore negative. Outside Victoria the vertical pin is meant to be earth/chassis ground, consistent with Australian Standards for Type I 240 volt outlets; therefore, the top of the T is positive on a negative-earth vehicle. Older positive-earth vehicles are still in service, so actual polarity at the outlet can be random.
See also 
- Banana connector
- Battery terminal
- Binding post
- Blade connector
- RCA connector
- Speaker terminal
- Telephone plug
- Phone connector (audio)
- Universal Serial Bus
- "Power DIN Connectors", CUI Inc, retrieved 2012-01-21
- Hosiden product guide
- Adapters: output plug/cord options See for pin configuration
- "Access Communications Snap and Lock plug information". Accesscomms.com.au. 2007-07-10. Retrieved 2011-06-22.
- "Mini-IEC Output Plug reference sheet". Accesscomms.com.au. 2007-07-10. Retrieved 2011-06-22.
- "W.S. Deans". W.S. Deans. Retrieved 2011-06-22.
- Common charging and local data connectivity, Open Mobile Terminal Platform, February 2009
- "Unsafe Battery Charging Leads and Small Portable Generators", The Government of Western Australia, Department of Commerce, retrieved 2012-04-09
- BD Batteries Voltage Drop Calculators - Determine voltage drop of wires from 30-4/0 AWG Copper and Aluminum
- GlobTek, Inc has a data page that could be used to further research these and other connectors.
- Low voltage connection basics
- Plug list of output cable
- Craftec output cord options
- MilSpec connector pin color code to part number cross reference
- forum posting on DIN/Powerlet socket and similar but different John Deer socket
- 12vAdapters.com has a guide on figuring out connector tip size.
- Manic Salamander FAQ compares and contrasts SAE with other common motorcycle accessory outlets
- US Patent 7,033,209 (patent application 20050014408) Vehicle accessory power connector—includes diagrams of SAE connector