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Home >> BMW >> 2018 >> X3 M40i >> Repair and Diagnosis >> External Pages >> Different car >> Section 763 (Functional Descriptions - F25 - Charging System, Anti-Theft, Body Electrical Systems) >> Charging System - Functional Description >> Alternator >> Characteristic curve and setpoint values

Characteristic curve and setpoint values

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The oscilloscope represents the voltage progression of an intact alternator. The level of the individual waves depends on the current load of the alternator. The length of the waves depends on the engine speed. The higher the engine speed the shorter the waves. At idle speed with consumer units switched on, an error-free alternator must deliver the following characteristic curve:

Fig 1: Alternator Characteristic Graph
G09908595Courtesy of BMW OF NORTH AMERICA, INC.
Index Explanation
1 Voltage
2 Characteristic curve
3 Frequency

Observe the following target values for the alternator:

Size Value
Voltage range 6 to 16 V
Data frequency on serial data interface BSD 1164 to 1236 bit/s
Data frequency on serial data interface LIN 19200 s
Maximum temperature of the stator winding 260 °C
Maximum speed 20000 rpm
Temperature range of controller -40 to 140 deg C