User's Manual

Intelligent technology 203
Controls Safety Driving tips General maintenance Self-help Technical data
Dynamic power management
While the vehicle is moving, this function distributes the available
power to the various electrical components and systems according
to their requirements. The power management ensures that on-
board systems do not consume more electrical power than the
alternator can supply, and thus maintains the maximum possible
battery power level.
Note
• The power management system is not able to overcome the
given physical limits. Please remember that the power and life of
the battery are limited.
• A warning message will appear ⇒ page 204, “Driver message in
the instrument cluster display” if the battery power has dropped to
a level where reliable starting is impaired.
Points to remember
Starting ability has first priority.
Short trips, city traffic and low temperatures all place a heavy load
on the battery. In these conditions a large amount of power is
consumed, but only a small amount is supplied. The situation is also
critical if electrical equipment is in use when the engine is not
running. In this case power is consumed when none is being gener-
ated.
In these situations you will be aware that the power management
system is intervening to control the distribution of electrical power.
When the vehicle is parked for long periods
If you do not drive your vehicle for a period of several days or weeks,
the power management will gradually shut off the on-board
systems one by one, or reduce the amount of current they are using.
This limits the amount of power consumed and helps to ensure reli-
able starting even after a long period.
Please note that certain convenience features, such as the Audi
advanced key*, the remote control key or the electrical seat adjust-
ment may not be available when you unlock the vehicle. These func-
tions will be restored when you switch on the ignition and start the
engine.
With the engine switched off
If you listen to the radio or use the other MMI functions when the
engine is not running, this will discharge the battery.
The MMI display will show this warning message before the battery
power drops to a level where the starting ability is impaired.
Please start engine, otherwise system will switch off
in 3 minutes.
This message warns you that the system you are using will be
switched off automatically after 3 minutes. You should therefore
start the engine if you wish to continue using the system.
When the engine is running
Although the alternator generates electrical power, the battery can
still become discharged while the vehicle is being driven. This can
occur when a lot of power is being consumed but only a small
amount supplied, especially if the battery is not fully charged
initially.
To restore the necessary energy balance, the system will then
temporarily shut off the electrical components that are using a lot
of power, or reduce the current they are consuming. Heating
systems in particular use a large amount of electrical power. If you
notice, for instance, that the seat heating* or the rear window
heater is not working, they may have been temporarily switched off
or regulated to a lower heat output. These systems will be available
again as soon as sufficient electrical power is available.
You may also notice that the engine runs at a slightly faster idling
speed. This is quite normal, and no cause for concern. The increased
idling speed allows the alternator to meet the greater power
requirement and charge the battery at the same time.
document_0900452a8179700c.book Seite 203 Donnerstag, 22. März 2007 10:19 10