1 Series E87 120d (N47) 5-door
Both battery cables are routed on the vehicle underbody on the BMW 1-Series and BMW 3-Series.
System functions
The following system functions of the power supply system are described:
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Power management with engine running:
"Basic Power Management" functions with standard equipment and "Advanced Power Management" with High
equipment level
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Emergency operation in the event of bitserial data interface failure
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Energy management even when engine is not running:
Power supply for control units, consumer cutoff of auxiliary consumers and off-load current monitoring
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Data transfer for power supply
Power management
The power management system is the most important component of the energy management system.
The power management system is a software package in the engine control unit (DME or DDE).
When the engine is running, the power management system regulates the alternator voltage.
Depending on the vehicle's equipment, there are 2 versions of the power management:
•
Basic Power Management (BPM)
> on vehicles with standard equipment and only a few items of special equipment
Basic Power Management controls the idle speed.
Basic Power Management also specifies the charge voltage according to demand.
•
Advanced Power Management (APM)
> on vehicles with High equipment level, e.g. with the following items of special equipment:
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CCC: Car Communication Computer
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M-ASK: Multi-audio system controller
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BMW "Professional" radio in US version
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Telephone in US version.
Advanced Power Management is only available with the intelligent battery sensor.
Advanced Power Management gives precise consideration to the current battery condition: The intelligent
battery sensor reads the corresponding data.
When the engine is running, the power management system regulates the following:
•
Alternator voltage regulation
When the engine is running, the alternator generates a variable voltage, the alternator voltage.
This variable alternator voltage is regulated by the power management according to the following criteria:
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Nominal value for alternator voltage:
The respective nominal value for alternator voltage depends on how many electrical consumers are
switched on.
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Battery temperature:
To prevent the battery from overheating, the optimum charge voltage is regulated.
The alternator voltage is regulated by the engine control unit (DME or DDE).
The alternator should always deliver as much current as the electrical consumers need.
SBT Power supply E81, E82, E87, E90, E91, E92, E93
BMW AG - TIS
23.01.2013 00:52
Issue status (12/2007) Valid only until next DVD is issued
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