3 Series E91 330xi (N52) TOUR
The engine control unit adapts the alternator voltage as follows, depending on the consumers in use:
-
By increasing engine speed
-
By increasing excitation current to alternator coils
The data is exchanged via the bitserial data interface.
•
Battery charging regulation
On vehicles without intelligent battery sensor, the battery temperature (for example) is calculated.
On vehicles with intelligent battery sensor, the battery condition is recorded precisely by the intelligent
battery sensor.
•
Load-dependent reduction of some consumers
> Only on vehicles with High equipment level and intelligent battery sensor
On vehicles with intelligent battery sensor, consumers may be reduced or even switched off altogether,
even if the engine is running.
This consumer cutoff reduces current consumption in critical situations.
This ensures that the battery is not discharged.
The affected consumers are either switched off completely of their power output is reduced.
On vehicles with diesel engine, the power consumption of the electric auxiliary heater is regulated.
[more ...]
Emergency operation in the event of bitserial data interface failure
If the bitserial data interface between the engine control unit and the alternator is interrupted, the alternator
voltage will be regulated to a constant 14.3 V.
Energy management system
The energy management system is software package in several control units, e.g.:
•
CAS: Car Access System
•
JBE: Junction box electronics
•
Engine control unit: DME or DDE).
The energy management system monitors and regulates the power supply, even when the engine is not running.
•
Power supply for control units
To ensure that the vehicle retains its starting capability, there are two additional terminals for permanent
current (terminal 30):
-
Terminal 30g (active)
-
Terminal 30g-f (cutoff in case of fault, only on vehicles with High equipment level).
These new terminals allow consumers to be cut off and off-load current to be monitored when the vehicle is
our of use.
•
Auxiliary consumer cutoff
Terminal 30g (terminal 30 active): Terminal 30g means "active continuous positive": Components with
power supply via terminal 30g are switched off according to time.
The Car Access System (CAS) uses terminal 30g as follows to effect a time-controlled cutoff of control
units and components with power supply: Approximately 30 minutes after terminal R is switched OFF,
the power supply for these components is switched off. This prevents the battery from being subjected to
excess load by the electrical consumers for too long when the vehicle is out of use.
SBT Power supply E81, E82, E87, E90, E91, E92, E93
BMW AG - TIS
22.02.2013 01:45
Issue status (12/2007) Valid only until next DVD is issued
Copyright
Page - 5 -
