1、MSD High-Voltage Interlock Failure
A low-voltage auxiliary contact can be designed on the high-voltage connector being tested. During connector insertion, the high-voltage contact contacts first, followed by the low-voltage auxiliary contact.
During connector removal, the low-voltage auxiliary contact opens first, followed by the high-voltage contact. The high-voltage interlock circuit outputs a certain voltage through a resistor, passing it through the low-voltage auxiliary contact of each MSD or high-voltage connector, back to the detection circuit, and then divided down to ground through an input resistor.
Insulation resistance is a physical quantity that measures the insulation performance of a dielectric. It is numerically equal to the dielectric resistance and is measured in MΩ.
In electric vehicles, insulation resistance refers to the insulation resistance of a high-voltage component relative to the vehicle ground at a certain DC voltage.
Under a certain DC voltage, the insulation resistance between the high-voltage component and the vehicle ground falls below a safe resistance.
2.1.1. Power off the vehicle, disconnect the battery and the vehicle, and measure the vehicle insulation and battery insulation separately. Method: Unplug the main circuit high-voltage wire at the battery end (or directly unplug the battery output terminal at the three-in-one).
2.1.2. Generally, vehicle insulation faults are reported by the battery. Therefore, even if the battery or vehicle reports an insulation fault, it is not necessarily a battery problem. Note: The national standard requires insulation resistance to be no less than 100Ω/V for DC and no less than 500Ω/V for AC.
Step 1: If possible, replace the charging station to rule out the possibility that the charging station is causing the BMU wake-up failure.
Step 2: Plug in the charging cable and use a multimeter to measure the voltage between A+ at the high-voltage box and vehicle ground. If the voltage is normal, the battery manufacturer should provide the solution. If the voltage is abnormal, coordinate with the vehicle and charging station manufacturers for investigation.
