Battery: Description and Operation
Voltage Supply
Battery
A battery under the driver's seat supplies the voltage. Since there are fewer variations in temperature, this location provides more stable performance than batteries mounted in the engine compartment. In the event of an accident, a safety switch (integrated into the primary battery relay in the distributor) disconnects the battery from the vehicle electrical system. In an emergency, the connection can been established via a push-button switch on the relay.
Battery capacity for the Cayenne S and Turbo ranges from 450A/95 AH (standard) up to 550A/11OAh (Cayenne Turbo with parking heater and multimedia options).
The generator is water-cooled and has a nominal output of 2660 watts, corresponding to a maximum current of 220 A.
After vehicle servicing, the battery should be checked and fully charged before the vehicle is returned to the customer.
The vehicle interior has six 12V sockets for connecting additional electrical devices (5 sockets in the non-smoker package). These are positioned as follows:
- Two sockets underneath the glove box in the passenger foot well.
The non-smoker package omits the additional socket in the front of the ashtray I drawer (middle of the instrument panel).
- One socket in the rear passenger compartment underneath the air vents in the center console.
- Two sockets in the luggage compartment in the side trim panels in front of the left and right storage compartments.
- An additional 12V socket (optional) in the rear bench seat. The second socket is in the mirror-image position to the other beneath the air vent in the center console.
Distributor
The circuitry of the vehicle electrical system is similar to that of the sports cars. Separating the electrical system areas provides good protection against mutual interference and shorts in the individual power circuits.
The distributor is located next to the battery beneath the driver's seat.
Fuse/Relay Panels
Electrical fusing has been designed for the particular operating requirements of the Cayenne. In order to counteract voltage loss and power overload the fuse and relay panels were made readily accessible, corresponding to the vehicle's power circuitry.
A fuse panel is located on each side of the instrument panel.
A combination relay and fuse panel is located to the left of the radiator reservoir in the engine compartment.
There is also a relay panel on the driver's side beneath the instrument panel.
Electrical System Control Module
The electrical system control module functions primarily to protect the battery against cyclical overcharging. A large quantity of input data is managed by the electrical system control module, since electrical system management controls driver-related functions and system integrity must always be maintained. Electrical system status is determined primarily by comparing the measured voltage with the permissible voltage lower limit.
The electrical system status is determined by battery voltage parameters and data from heavy current loads of short duration.
In addition, the current control states of systems used by the driver are stored in the electrical system control module.
The electrical system control module communicates with the DME to provide an increase of idle speed if required to improve the electrical system status. If the system status is negative, convenience-related electrically powered units can be switched off, as required. The voltage thus gained can be then channeled to other control devices via the CAN-Bus. Before such units are cut off (e.g., cigarette lighter, etc.) the driver receives a "Battery Low" warning signal. Once the system status is no longer critical, the units are switched on in the reverse order that they were shut off. Diagnosis of the electrical system control device is performed using the Porsche System Tester 2.
Function: Vehicle Electrical System Management
Circuit Diagram
