On-Board Electrical System Control - SN00.00-P-0070-18S

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On-board electrical system management permanently monitors the status of the vehicle and the on-board electrical system components involved (e.g. the batteries) and distributes the available energy.

If a drop in the state of charge is detected (e.g. by activation of all comfort and convenience equipment), the output requests of the consumers will gradually be reduced (shutoff stages).

As the state of charge decreases, the remote functions will gradually be deactivated in stationary phases as well (e.g. stationary heater controller, vehicle status query).

In the case of multi-voltage on-board electrical systems (48 V on-board electrical system or high-voltage on-board electrical systems), however, it is possible to recharge the 12 V battery. The prerequisite for this is an appropriate state of charge of the 48 V or high-voltage battery.

This charging will end automatically when defined charging state thresholds are reached to protect the 48 V or high-voltage battery.

If states of charge of the 48 V or high-voltage battery fall below defined levels, these energy storage units will open internal switches (the contactors) to prevent damage to the 48 V or high-voltage battery as a result of further discharging.

For the contactors to close requires either the vehicle to be unlocked or circuit 15 (ignition on) to be switched on.

If the 12 V battery is also discharged, the vehicle must be supplied with power externally via the jump-start connection point.

For external charging processes, the 48 V battery will be charged first in the case of 48 V vehicles, then the 12 V battery. This helps to ensure that starting capability is maintained via the integrated 48 V starter alternator (ISA).

The 48 V battery can also be charged via a 12 V charger, but the charging process will take roughly four times as long.

If the hood and/or trunk lid is/are open, the contactors of the 12 V/48 V battery or the high-voltage battery will be opened for safety reasons.