Starter unit, active hybrid: Notes

The starter unit enables comfortable starting of the combustion engine from a vehicle standstill or during electric driving via the starter generator.

An auxiliary battery is provided so that the vehicle electrical system is not affected. This auxiliary battery is necessary because a sufficient voltage supply e.g. for driving stability control systems must be ensured while the vehicle is driving.

To avoid overcharging the auxiliary battery, the cut-off relay is closed when a certain engine speed is exceeded. However, to ensure that the cut-off relay is not loaded, the closing action must take place at the smallest possible load: To achieve this, the DC/DC converter in the electrical machine electronics (EME) adjusts the vehicle voltage to the voltage of the auxiliary battery. The cut-off relay then remains closed until the combustion engine is switched off again.

In case of a fault in the high-voltage system or in the intelligent battery sensor of the auxiliary battery, the cut-off relay remains closed.