ISO 4165 was established in 1979 to define a standard for the connection of external appliances to the supply system of road vehicles. The design is based on a connector system which was already in use in German military vehicles of the 1940s. ISO 4165 was last reviewed in 2018, however no revision was deemed necessary.

Often, a socket according to ISO 4165 is located near the car ashtray as power source for the cigarette lighter. However, over the last years, the applications became more diverse with the possibilty to directly connect portable refrigerators, tire compressors handlamps, fans, etc. With the help of a current adapter, vehicle operators can also supply GPS devices or mobile phones.

Using a simple adapter, plugs according to ISO 4165 can fit into sockets according to SAE J563 - another common standard for automotive accessory sockets. The advantage of the ISO system however is that the contact connection is safer due to the use of a latching spring at the positive pole.

Scope of ISO 4165

This standard specifies the dimensions and electrical characteristics of the double-pole connection required for the interchangeability of the electrical connections used to supply additional appliances in road vehicles with a nominal supply voltage of 12V or 24V DC at up to 12 amps.