Functions
Energy management
Basic energy management
Vehicles with BSD (bit-serial data interface)
Basic energy management is used in current
BMW vehicle types with a BSD interface.
The main component of basic energy
management is the software integrated in the
DME/DDE for controlling the charging voltage.
The specified charging voltage can be
increased in the event of increased current
consumption in the vehicle electrical system.
The specified charging voltage is transmitted
via a bit-serial interface from the DME/DDE to
the alternator.
The energy management system also
features the option of load/consumer
deactivation. The power output of the heated
rear window can be reduced in the event of
excessive current consumption in the vehicle.
The charging voltage can be regulated as a
function of the outside temperature. This
enables the battery to be charged to optimum
effect.
At cold temperatures the charging voltage can
be increased in order to achieve a higher
capacity.
At high temperatures the charging voltage is
reduced in order to avoid excessive gassing.
The maximum charging voltage is 14.8 V.
Idle speed increase
If current is drawn from the battery in
stationary operation with the alternator
operating at maximum, the idle speed is
increased by a maximum of 200 rpm on
vehicles with petrol/gasoline engines.
The higher transmission ratio between the
engine and the alternator renders this
intervention unnecessary in the case of diesel
engines. The alternator is already running with
sufficiently high revs.
Load/consumer deactivation
Some loads/consumers can remain switched
on even when the vehicle has stopped. In the
interests of protecting the battery, these loads/
consumers are deactivated after terminal R
"OFF" with a delay of 16 minutes or
immediately with the "Go to Sleep Mode"
diagnosis telegram.
Load/consumer deactivation is coded in such
a way that it responds immediately when the
following conditions are satisfied:
***8226; Terminal R "OFF"
***8226; Central double-locking engaged
***8226; All doors, engine bonnet/hood, rear lid and
rear window on the Touring are closed
Load/consumer deactivation is cancelled and
the delay time restarted each time there is a
change at specific input signals.
Load/consumer deactivation is handled as
above if one of these conditions is missing.
In the interests of reducing current
consumption by the ZKE (central body unit),
the ZKE switches after certain conditions to a
rest state in which only restricted functions are
possible.
The following must be deemed preliminary
conditions for sleep mode:
***8226; Terminal 30 passive
***8226; Power windows, central locking, remote
control and anti-theft alarm system passive
1 - Charging voltage increase
Index Explanation
1 Increased charging voltage
2 Normal charging voltage
16
6
The system switches to sleep mode
***8226; 1 second after power windows deactivated,
load/consumer deactivation, interior lights
passive, no diagnosis mode and the K-bus
in "Sleep" status
***8226; 1 second after the Go to Sleep Mode
telegram
Sleep mode is quit again when:
***8226; Signal change occurs at a status field with a
signal identified with "Wake Up"
***8226; A valid remote control signal is detected
***8226; The K-bus is activated
The functions must then be categorized as
passive if actions such as holding or delay
times are no longer active
Emergency operation functions
If the BSD is interrupted or faulty, the following
emergency operation functions are activated:
***8226; No load/consumer deactivation
***8226; Constant charging voltage (14.3 V)
***8226; Fault memory entry "Bus communication
BSD
