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12V On-Board Electrical System, Basic Function - GF54.10-P-1014A

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12 V on-board electrical system 

The 12 V on-board electrical system normally includes all components for voltage generation, voltage regulation and energy storage. The 12 V on-board electrical system supplies electrical energy to the electrical consumers of various systems, including the interior lighting, exterior lighting and engine management systems.

On vehicles with a 12 V alternator, the necessary electrical energy is generated when the combustion engine is running. This is stored in the 12 V on-board electrical system battery. Vehicles with 48 V technology, hybrid vehicles and electric vehicles do not have a 12 V alternator. On these vehicles, the necessary electrical energy for the 12 V on-board electrical system is provided via a DC/DC converter by the 48 V battery or by the high-voltage battery.

Secondary 12 V on-board electrical system (vehicles for highly automated parking) 

The 12 V on-board electrical system is supplemented by a secondary 12 V on-board electrical system, which is supplied from the 12 V on-board electrical system in normal operation through a DC/DC converter. Electrical energy is stored in the secondary 12 V on-board electrical system battery. In the event of a failure of the 12 V on-board electrical system, the secondary 12 V on-board electrical system supplies components of the highly automated parking function.

Schematic diagram of 12 V on-board electrical system 

G13772692Courtesy of MERCEDES-BENZ USA
  Detailed information     
  12 V on-board electrical system with support battery, detailed information Model 223 with engine 279 GF54.10-P-1018A