Brief component description: Alternator

A more powerful alternator is installed in conjunction with the automatic engine start-stop due to battery discharge during the engine shutdown.

The alternator assumes the following functions during driving:

• Retention of the required level of vehicle voltage
• Supply to all electrical consumers

The controller regulates the output voltage of the electrically excited alternator with uncontrolled rectifier by applying the excitation current.

The Digital Engine Electronics (DME) controls the alternator by using the following functions:

• Switching the alternator on and off on the basis of defined parameters
• Temperature-dependent maximum permitted power consumption of the alternator
• Calculation of the drive torque and current based on the transmitted controller parameters
• Control of the reaction of the alternator with addition of high power consumers (load-response function)
• Diagnosis of the alternator and data line between the alternator and the Digital Engine Electronics (DME)
• Storage of faults that occur on the alternator in the fault memory of the Digital Engine Electronics (DME)
• Activation of the charge indicator light in the instrument cluster (KOMBI) when a fault is detected

Courtesy of BMW OF NORTH AMERICA, INC.