Operating Modes of the APM

Depending on the direction in which the APM converts the voltage, two operating modes exist: downward conversion and upward conversion.

Although the E72 cannot be jump started, the high voltage battery can be charged via the 12 Volt side. One responsibility of the APM is to upconvert the voltage to charge the high voltage battery.

Fig 1: Identifying Auxiliary Power Module Operating Modes

Courtesy of BMW OF NORTH AMERICA, INC.