Reduce Consumers, Basic Function - GF54.10-P-1011A

Model all (4xWD) 

Model all (CAR) 

Overview 

This document contains information on:

• General 
• Function 
  • Vehicles with PRE-SAFE® system 
  • Vehicles with 48 V technology, hybrid vehicles or electric vehicles 

General 

Switching off or shutting down various functions relieves the load on the 12 V on-board electrical system, if the required electrical power can no longer be supplied. This serves to avoid any significantly negative charge balance for the on-board electrical system battery while also guaranteeing vehicle mobility.

Irrespective of the function described here, consumers can also be switched off via the range maximization function. Range maximization is available in electric vehicles depending on the model. If it is activated, comfort systems that are not relevant to driving are partially or completely switched off. In this way, more energy for driving is available in the high-voltage battery.

Function 

Consumer reduction is activated when one of the following conditions occurs:

• The on-board electrical system voltage drops to a defined value.
• A high load is detected at the power source supply (alternator or DC/DC converter).
• The maximum discharge current of the on-board electrical system battery has been reached. The maximum value here depends on the charge level of the on-board electrical system battery.

The first consumer's power consumption level is reduced at the earliest 5 s after the system start. If the cutback conditions remain unchanged, the power consumption of one further consumer will be reduced or shut down every following second.

Vehicles with PRE-SAFE® system 

PRE-SAFE® measures have a high energy requirement. Therefore when they are triggered, several high-performance consumers are quickly reduced or shut down for the duration of the measures.

Vehicles with 48 V technology, hybrid vehicles or electric vehicles 

The energy requirement is provided by the transfer of energy from the 48 V or high-voltage on-board electrical system. If the state of charge of the 48 V battery or the high-voltage battery drops below a defined limit value, energy is no longer transferred. Various functions are derated or switched off depending on the vehicle equipment involved.

At the same time as the actions in the above table, the output of the air conditioning and seat heating is restricted to match the current status of the on-board electrical system.

The alternator management prevents the battery from being discharged specifically for recuperation purposes as long as the on-board electrical system voltage is below a defined value.

If none of the triggering conditions are met, consumer reduction is canceled. The switched-off consumers or functions are switched-on again in the reverse order with a waiting time in each case of 1 s. With circuit 15R OFF, and depending on the charge level of the on-board electrical system battery, various consumers (e.g. telematics, stationary heater, standing light) are switched off, but not in a specific sequence.