Mercedes-Benz Series 218 Coupe Introduction Into Service Manual page 74

The driving operation energy management
subsystem is divided into the following subfunc-
tions:
• Voltage control
- Determine battery charge level
- Charge on-board electrical system battery
- Alternator control
• Dynamic idle control
• Consumer reduction
Engine standstill energy management
The engine standstill energy management
subsystem ensures that the on-board electrical
system remains stable and that the vehicle can be
started after the engine has been switched off.
This functionality is integrated in the rear SAM
control unit and allows the on-board electrical
system battery to remain idle for long periods.
The engine standstill energy management
subsystem consists of the following subfunctions:
• Consumer shutoff
• No-load current management
• External charging/jump starting
Consumer shutoff
Consumer shutoff is activated when the on-board
electrical system voltage drops below U = 11.8 V or
when the engine is off (circuit 61 OFF) and circuit
15 ON is switched to circuit 15R ON In addition to
consumer reduction from the driving operation
energy management subsystem, a consumer is
shut off every t = 5 s.
When the on-board electrical system voltage stabi-
lizes at a value above U = 11.8 V, the consumer
shutoff function is nevertheless not canceled. The
consumers which have been shut off are only put
back into operation after the system is reset by
turning the transmitter key to circuit 15C.
– This printout will not be recorded by the update service. Status: 09 / 2010 –
No-load current management
The no-load current management function ensures
that the vehicle can be started.
This function is integrated in the rear SAM control
unit and allows the vehicle to remain idle for
extended periods without the on-board electrical
system battery discharging completely.
For this purpose, consumers on circuit 30g are
disconnected from the power supply through actu-
ation of the no-load current shutoff relay.
The no-load current management function allows
increased energy consumption for a certain period
of time after the engine is shut off (max.
t = 75 min). This is desirable, for example, when the
radio is left switched on while the car is being
washed.
External charging/jump starting
If the on-board electrical system battery does not
have sufficient capacity to start the engine, it must
be charged or a jump start must be carried out.
i Note
During the jump starting process or during testing
work in the workshop, one of the front doors must
be opened. The alternator management system
thus switches to jump starting or workshop mode
and the alternator voltage is raised to U = 13.9 V.
i Note
The on-board electrical system battery may only
be charged with direct current. Approx. 10% of the
capacity is recommended as the charging current.
Introduction of the New CLS-Class, Model Series 218 Coupe
Energy management
73
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