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 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 amperes and 6, 12, 24, or 48 volts AC and DC. For use either indoors or outdoors.
The Anderson Powerpole has been adopted by the amateur radio community[9] as their standard 12-volt DC power connector for everything from radios to accessories. It is a bit more expensive than the older de facto standard of the 2-wire trailer plug and Molex connector, but provides a more reliable electrical connection (both mechanically and electrically) and is easier to adapt to a wider range of wire gauges. 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.
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.
