17
Energy management
control unit J644
Use is made for the first time in the
Audi A8 ´03 of a battery and energy
management control unit.
The increase in the number of electronic
components and controls in the vehicle gives
rise to a far greater power requirement. The
uncontrolled tapping of power can cause a
major drop in the level of electrical energy
available in all vehicle statuses.
The principal tasks of the energy
management control unit are to monitor the
battery charge, to regulate loads via the CAN
in extreme circumstances, to minimise
current consumption by deactivating
functions and to ensure optimum charging
voltage. The aim is to avoid excessive battery
discharge and thus ensure that the vehicle
can always be started.
Fitting location
The energy management control unit J644 is
installed on the right of the luggage
compartment in the immediate vicinity of the
battery.
Functions
The energy management control unit J644 is
responsible for constant monitoring of the
battery, which includes checking the state of
charge (SOC) and starting capability. The
control unit regulates the optimum alternator
charging voltage with the engine running. It
can implement load shedding (reduce the
number of loads) and increase idling speed.
To reduce the closed-circuit current with the
engine OFF, the energy management control
unit can deactivate loads via the CAN in
extreme circumstances and thus prevent
excessive battery discharge.
SSP287_025
SSP287_039
