|
Hi,
Most cigarette lighters are on-demand appliances built to DIN standard in which on-demand appliances are B+ (Battery Positive or constant Hot).
DIN is an abbreviation for the Deutsches Institut für Normung e. V, an institution of trade and industry responsible for the preparation of National Standards in Germany, similar to our own ANSI - American National Standards Institute. Since DIN had already created an electrical wiring standard, ANSI (as well as many other countries' standards committess) simply adopted it.
Early in the Industrial Age, it was determined that adopting a set of standards would insure consistency and interchangability in the design and manufacture of components from one supplier to another. Additionally, it allowed educators to ensure they were teaching standardized techniques in engineering and science disciplines to insure a consistent follow-on workforce for Industry.
These standards included everything from Pipe and Tubing standards, Screw, Bolt Thread size and pitch standards, to electrical connectors, packaging sizes for appliances (such as Din sized Radios) etc. There is even a DIN standard for electrical wiring. As such, a Car Manufacturer knew exactly how large a Radio would be from a supplier and could design the dash to readily accept it, etc.
In the electrical wiring DIN standard, it was decided to wire all on-demand appliances (such as cigarette lighters, door operated interior lights, etc.) to B+ (constant Hot), as having to energize all other electrical components (such as the ignition, fuel pump, Relays, etc.) was inefficient. This is the reason most lighters are B+. Hope this helps...
Happy Motoring!... Jim'99
|