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

MODEL 212 as of model year 2014 

Fig 1: Energy Management Communication Diagram

Courtesy of MERCEDES-BENZ USA

Power supply via the following sources is not shown:

• On-board electrical system battery (G1)
• Additional battery (G1/7) (as of 01.12.2014 transmission 722, 725 and except engine 642 and except CODE 460 (Canada version) and except CODE 494 (USA version))
• ECO start/stop function additional battery (G1/13) (up to 30.11.2014, as of 01.12.2014 engine 642 and with CODE 460 (Canada version) or CODE 494 (USA version))
• High-voltage battery (A100g1) (model 212.095/098/298)
• Electrical machine (A79/1) (model 212.095/098/298)

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.

Energy management specifies the 12 V on-board electrical system. The correlation between the high-voltage and 12 V on-board electrical system is also described for hybrid vehicles (model 212.095/098/298). A comprehensive description of the high-voltage on-board electrical system is given in the function description for the hybrid system.

The following components are involved in energy management:

• Battery sensor (monitoring of on-board electrical system battery charge level)
• On-board electrical system battery (power storage and supply when the engine is off)
• Additional battery (emergency power supply for engaging transmission position "P" if on-board electrical system battery has been discharged) (as of 01.12.2014 transmission 722, 725 and except engine 642 and except CODE 460 (Canada version) and except CODE 494 (USA version))
• ECO start/stop function additional battery (on-board electrical system power supply with automatic engine start) (up to 30.11.2014, as of 01.12.2014 engine 642 and with CODE 460 (Canada version) or CODE 494 (USA version))
• Voltage dip limiter (series resistor) at positive terminal of on-board electrical system battery (as of 01.12.2014 except engine 642 and except CODE 460 (Canada version) and except CODE 494 (USA version))
• Alternator (except model 212.095) (power generation)
• CDI control unit or ME-SFI [ME] control unit (Alternator management (except model 212.095))
• Front SAM control unit (control of on-board electrical system support)
• Rear SAM control unit (master control unit energy management)
• Power electronics control unit (model 212.095/098/298) (energy supply from the high-voltage power supply to operate the vehicle; energy supply from the low-voltage power supply for charging the high-voltage battery)

Energy management consists of the following subsystems:

• Energy management 
• Major assemblies coordinator 

Energy management 

The energy management function 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: 

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 damage to and contamination of the vehicle interior as well as theft of loose parts from the vehicle 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 in excess of s ≥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 of the instrument cluster when the transport mode is active.

The energy management system'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 energy management system.

According to the energy management specifications, targeted interventions (function restrictions and changes) are carried out in individual electronics systems.

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

• Limitation of vehicle speed to v = 40 km/h
• Electric locking of front passenger door and rear doors, as well as trunk lid (model 212.0/1) or the liftgate (model 212.2)
• Deactivation of roof opening function on vehicles with CODE 413

  (Panoramic glass sunroof with top sliding sunroof) or CODE 414

  (Power 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, during 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 tilting/sliding sunroof (with CODE 414 (Power glass tilting/sliding roof)
• Side window(s)
• Trunk lid (model 212.0/1) or liftgate (model 212.2)

The following tasks are carried out by the energy management system:

• 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)
• Deactivate engine start/stop function
• Early opening of no-load current shutoff relay (F32k2)
• Restriction of closing reasons for quiescent current shutoff relay

Customs inspection (as of 01.12.2014): 

To make inspection of the vehicle interior and the luggage compartment easier for customs officers, the central locking can be unlocked temporarily by pressing the hazard warning system button (N72/1s5) in the upper control panel control unit (N72/1) with circuit 15C ON. The time and the kilometer reading at which this action was performed are stored.

Winter package (as of 01.12.2014): 

The mirror heaters and, on vehicles with diesel engine, the PTC heater booster (R22/3) are switched on at low outside temperatures. The blower can be operated at full power in order to demist/de-ice windows and outside mirrors.

Model 212.095/098/298: 

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

Apart from the energy flows in the high-voltage on-board electrical system, the energy management module in the CDI control unit or ME-SFI control unit additionally controls the voltage conversion and energy exchange from and to the 12 V on-board electrical system.

To this end, the CDI control unit or the ME-SFI [ME] control unit communicates over the hybrid-CAN with the power electronics control unit and over the drive-LIN with the alternator (model 212.098/298).

The 12 V on-board electrical system is supplied with energy primarily from the high-voltage on-board electrical system ("buck mode"). When the engine is off or in boost mode, the 12 V 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 electrical machine. 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 12 V on-board electrical system is supplied with energy from the high-voltage on-board electrical system in order to safeguard 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 of high-voltage battery charge level)
• Power electronics control unit (High/low voltage energy conversion)

Major assemblies coordinator 

The major assembly coordinator is integrated in the CDI control unit or the ME-SFI control unit and it forms the interface between the energy management and the alternator (except model 212.095). The CDI control unit or the ME-SFI control unit communicates with the alternator over the drivetrain LIN. The major assembly coordinator regulates the alternator's power output to match the energy management system 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 control unit
• Alternator (except model 212.095)
• DC/AC converter control unit (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 

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

• DC/AC converter function (with CODE U80 (115V socket))