Energy management, function - GF54.10-P-0003FL

MODEL 212.0/2 up to 28.2.13 

Function requirements, general 

• Circuit 30 ON

Energy management, general 

Energy management manages the provision (supply) and consumption (management) of electrical energy with the aim of ensuring the startability of the engine and a stable supply to all electrical consumers.

In energy management, the low-voltage on board electrical system (12 V) is described exclusively. For hybrid vehicles (Model 212.095/098/298) the correlation between the high and low-voltage on-board electrical system is also described.

A comprehensive description of the high-voltage on board electrical system is provided in the function description for the hybrid drive system.

The following components are involved in energy management:

• Battery sensor (B95)

  (monitoring of charge level of on-board electrical system battery (G1))

• On-board electrical system battery (G1)

  (power storage and supply when the engine is off)

• Additional battery for ECO start/stop function (G1/13)

  (with code (B03) ECO start/stop function)

  (on-board electrical system-power supply with automatic engine start)

• Alternator (G2) (except model 212.095) (power generation)
• CDI control unit (N3/9) (for diesel engine) or ME-SFI [ME] control unit (N3/10) (for gasoline engine)

  (alternator management (except model 212.095))

• Front SAM control unit with fuse and relay module (N10/1)

  (control of on-board electrical system support) (with code (B03) ECO start/stop function)

• Rear SAM control unit with fuse and relay module (N10/2) (on-board electrical system management, master control unit energy management)
• Power electronics control unit (N129/1)

  (for model 212.095/098/298)

  (Energy supply from the high-voltage power supply to operate the vehicle, energy supply from the low voltage network for charging the high-voltage battery (A100g1))

Energy management consists of the following subsystems:

• On-board electrical system management 
• Major assemblies coordinator 

On-board electrical system management 

The on-board electrical system management monitors on-board power supply utilization and actively intervenes in the energy management (e.g. consumer shutoff). The aim is to ensure the starting ability of the engine and a stable power supply to all electrical consumers.

Transport mode (as of 1.6.12):

The transport mode is activated in the production plant at the end of the production process, and it sets the overall vehicle into a defined special condition.

With targeted interventions in individual electronics systems the following is achieved:

• Reduction of shipping damage and accidents
• Best-possible charging of on-board electrical system battery through optimized energy management
• Avoidance of any damage and soiling of the interior as well as theft of loose parts from the interior
• Discontinuation of transport protection seal

The transport mode remains active on its way from the production plant to the dealers and company-owned sales and service outlets around the world up to the so-called delivery inspection and the final handover to the end customers.

The transport mode is automatically deactivated from a total distance traveled of more than 350 km whereupon it cannot be activated again. Up to this limit, the transport mode can be deactivated using the diagnosis tester or key combinations at any give time and activated with the diagnosis tester again.

The fault memory is not actively deleted when the key combination is used for deactivation. This means that the "Transport mode active" fault entry remains stored. This must be deleted using the diagnosis tester when the vehicle is inspected for the first time.

To support the processes in Sales and Logistics the vehicle's currently possible residual service life and, if necessary, appropriate care instructions for the on-board electrical system battery are shown on the multifunction display (A1p13) in the instrument cluster (A1).

The on-board electrical system management's continuously determined condition of the on-board electrical system battery is rendered fully transparent at any given time without the use of any additional measuring instruments during the vehicle delivery period.

This display provides the operating personnel with specific instructions on what to do to guarantee a high delivery quality with regard to the on-board electrical system battery.

The individual transport mode functionalities are split up for numerous individual systems. The core here is the central control of the transport mode by the on-board electrical system management.

In keeping with the specifications of the on-board electrical system management, targeted interventions are made (function limits or modifications) in individual electronic systems.

The following function limits or modifications are implemented during the transport mode:

• Limitation of vehicle speed to 40 km/h
• Electric locking of front passenger door and rear doors as well as

  trunk lid (model 212.0) or

  the liftgate (model 212.2)

• Roof opening deactivation for vehicles with code (413) Panoramic glass sunroof with top sliding sunroof or code (414) Electric glass tilting/sliding roof
• Monitoring of circuit 15 at standstill and acoustic feedback, when the vehicle is at a standstill for t > 10 s with the ignition switched on and the engine switched off
• Optimized quiescent current management, when the vehicle is parked for an extended period (e.g. transportation by ship)
• Limit exterior light functions
• Implement display on instrument cluster
• Adjust fault memory handling

If, before activation of the transport mode, the following components are open, they can still be closed:

• Panoramic glass sunroof (with code (413) Panoramic glass sunroof with top sliding sunroof) or SHD (with code (414) Glass tilting/sliding roof)
• Side Windows
• Trunk lid (model 212.0) or liftgate (model 212.2)

The following tasks are implemented by the on-board electrical system management:

• Set specific consumer shutoff stages
• Optimized charging of on-board electrical system battery:
  • Activate fast battery charging
  • Deactivation of alternator management

    (except model 212.095)

  • Deactivation of engine start/stop function

    (With code (B03) ECO start/stop function)

• Early opening of no-load current shutoff relay (F32k2)
• Restriction of closing reasons for quiescent current shutoff relay

The following graphic shows the different "Vehicle transport mode" system statuses in the instrument cluster display.

Model 212.095/098/298:

Because of their drive technology, hybrid vehicles are equipped with an additional high voltage on-board electrical system (U = 140 V).

The energy management module in the CDI control unit or the ME-SFI [ME] control unit regulates the energy flows in the high-voltage on-board electrical system along with the voltage conversion and energy exchange from and to the low-voltage on-board electrical system.

To this end the CDI control unit or the ME-SFI [ME] control unit communicate over the hybrid-CAN (CAN L) with the power electronics control unit and over the drive-LIN (LIN C1) with the alternator (model 212.098/298). The low voltage on-board electrical system is primarily supplied with energy from the high voltage on-board electrical system ("Buck-Mode"). When the engine is off or in boost mode ("Boost-Mode"), the low voltage on-board electrical system is supplied with energy stored in the high voltage battery, and when the engine is on, with energy generated by the electric machine (A79/1). If the energy made available by the power electronics control unit does not meet the existing energy requirements, the alternator (model 212.098/298) will be switched on.

When outside temperatures are extremely low, the power electronics control unit supplies the low voltage on-board electrical system with energy from the high voltage on-board electrical system in order to protect the engine's starting capability ("Boost-Mode").

The following components are involved in the high-voltage energy management:

• High-voltage battery module

  (Energy storage and supply at engine OFF)

• Electric machine

  (high voltage on-board electrical system power generation)

• CDI control unit or ME-SFI [ME] control unit

  (energy management and alternator management (model 212.098/298))

• Battery management system control unit

  (Monitoring charge level of high voltage battery)

• Power electronics control unit

  (High/low voltage energy conversion)

Major assemblies coordinator 

The major assembly coordinator is integrated into the CDI control unit or the ME-SFI [ME] control unit and it forms the interface between the on-board electrical system management and the alternator (except model 212.095). The CDI control unit or the ME-SFI [ME] control unit communicates with the alternator via the drivetrain LIN (LIN C1). The major assembly coordinator regulates the alternator's power output to match the on-board electrical system management specifications taking engine load into consideration.

The recording and evaluation of the relevant variables for this are conducted by the following components:

• Rear SAM control unit
• CDI control unit or ME-SFI [ME] control unit
• Alternator (except model 212.095)
• DC/AC converter control unit (N24/3)

  (with code (U80) 115V socket)

Energy management contains the following subfunctions, which are described in separate documents:

• Engine on energy management, function 
• Engine off energy management, function 
• Energy management for engine start/stop function 

  (with code (B03) ECO start/stop function) 

• DC/AC converter function 

  (with code (U80) 115V socket) 

The "energy management for engine start/stop function" subfunction is viewed from an energy management point-of-view. Information on the "engine timing Start-Stop function" subfunction is documented in the "Common-Rail Diesel Injection (CDI) function" description (with diesel engine) or "gasoline injection and ignition system with direct-injection function" (with gasoline engine).