48 V On-Board Electrical System, Basic Function - GF54.10-P-1015A

Model All (CAR) 

with code B01 (48Vtechnology) 

Overview 

This document contains information on:

• General 
• Function 

General 

The 48 V on-board electrical system supplies all 48 V consumer (consumers with high energy requirement) with electrical energy. It also provides the electrical energy for starting the combustion engine with the starter-alternator.

Function 

When the combustion engine is running, the starter-alternator generates the electrical energy for charging the 48 V battery. Depending on the version, the starter-alternator is either driven via a belt or integrated into the drivetrain.

The 48 V on-board electrical system supplies the 12 V on-board electrical system with electrical energy from the 48 V battery via the DC/DC converter. No 12 V alternator is installed. In other words, the 12 V on-board electrical system replaces the conventional 12-V alternator with the DC/DC converter control unit. Apart from this, the 48 V on-board electrical system together with the 48 V on-board electrical system battery provides additional storage capacity throughout the overall system. The DC/DC converter control unit is the master control unit for energy management in the 48 V onboard electrical system.

The energy management in the 48 V on-board electrical system calculates the current and voltage limits for the power output of the integrated starter alternator to achieve an equalized charge balance for the 48 V on-board electrical system battery and to secure starting capability.

Courtesy of MERCEDES-BENZ USA

Example illustration of 48 V on-board electrical system