Section 131 (Generators & Regulators): Description
WARNING: This page is about a different car, the 2004 BMW Z4 and 2003 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.
Depending on equipment, different output generators are installed on Z4.
Battery charging voltage varies according to ambient temperature. At lower temperatures, battery is less susceptible to boiling over and can be charged at higher voltages. At high temperature, charging voltage is reduced to prevent loss of battery electrolyte through evaporation. The Digital Motor Electronic (DME) control unit controls output rate of the generator.