Test of Battery Junction Box (BJB/S-Box) in electric vehicles

Module of the Battery Management in electric cars

The Battery Junction Box (BJB) is a switching unit for the battery in an electric vehicle. It connects or disconnects the components in the vehicle, which need energy from the battery.

With one or more bus interfaces, this component is networked with the entire vehicle. The BJB is usually a switching box that switches the high-voltage connection on or off. It ensures that the high voltage is only applied to the necessary contacts when the ignition is switched on.

In these vehicles the high voltage can be up to 1000 VDC. The BJB has a safety function: in case of danger it disconnects the high-voltage battery from the electrical system including all electrical components of the vehicle.

For example, in the event of an accident it must be ensured that no high voltage is present in the vehicle in an uncontrolled state in order not to expose rescue workers to any danger.

Competences for BJB from GOEPEL electronic

  • End-of-Line (EOL)

    With an End-of-Line test system (EOL test) for Battery Junction Boxes we bring safety into the electric vehicle.

    All necessary functions of the BJB component are checked by the EOL tester. For example, the correct on/off switching of the high voltage switching elements is tested.

    The safety shutdown of the high voltage is checked with a simulated crash pulse. With the aid of a corresponding load simulation the current capacity of all high voltage paths is tested.

    We create the residual bus simulation of the automotive network environment according to the specifications of the project and implement it in the test. This is the only way to ensure correct communication with the DUT during the test. The BJB is contacted by an automated handling system.

  • High-voltage Test

    Since the energy storage is powered with high voltage, also the BJB is connected to these voltages. An insulation voltage test is therefore absolutely necessary as a safety test with a correspondingly high test voltage.

    This high voltage can be up to 4000 V DC.

    With our test systems for the high-voltage test of the Battery Junction Box, we prove the insulation voltage resistance and a required insulation resistance.

  • Alignment of high current sensors

    We realize hard- and software for the adjustment of high current sensors, which measure currents between -800 A DC and +800 A DC.

    These are sensors which record the current consumption from the storage and provide it to other components in the vehicle.
    This hardware and software can be integrated into function test systems.

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Markus Urbansky
M. Markus Urbansky