E-Box

E-box

The connection unit on the high-voltage battery is referred to as the E-box. It is the link between the battery cells and the HV connections for the lines to the power electronics. The E-box receives its commands from the battery manager, a separate control unit in the E-box.

The E-box has the following connections:
- 2 DC voltage connections (2 x 144 V plus and minus) at the transition between the high-voltage battery and service disconnector
- 1 DC voltage connection (1 x 288 V plus and minus) for power electronics
- Low voltage for control connection (CAN Hybrid/CAN Drive, fan, etc.) all of which are described in the following sections.

Contactors

When the service disconnector is plugged in, 2 of the 3 contactors establish the connection between the power electronics and the high-voltage battery. The battery manager activates the 288 volt direct current, which is then supplied to the power electronics. The uninterrupted pilot line that provides the continuous connection between all hybrid components is an essential requirement for activating the current. When the hybrid system starts up, a ballast resistor in the power transmission path is activated to pre-charge the contactors before they switch over and full power is made available.

NOTE: See chapter "Porsche high-voltage safety concept".

Service disconnector

A high-voltage fuse connected in series with the battery cells and a contact for the pilot line are located inside the service disconnector. When the service disconnector is pulled out, the high-voltage battery is disconnected from the remaining high-voltage components, which is a fundamental prerequisite for performing work on the high-voltage components.