lorenfb wrote:There most likely exists a test to determine if the pre-charge voltage of #3 equals approximately the HV of the battery.
If not, the system fails to allow the vehicle to enter the start mode, i.e. the Cx wasn't pre-charged and the HV main relay
is not activated.
Yes, there is. The motor inverter monitors the voltage of the main caps and permits startup when they start. From page 37 of the "EVC" manual for 2012's:
To connect the high voltage circuit, VCM first activates the system main relay 2 and pre-charge relay. As a result, the high voltage power is supplied to the respective systems via the pre-charge resistor in the pre-charge circuit. When the condenser inside the traction motor inverter is fully charged by the applied power, the traction motor inverter transmits a high voltage power supply preparation completion signal to VCM. Receiving the signal, VCM activates the system main relay 1 and deactivates the pre-charge relay. Then, normal power is supplied to the respective systems.
Thanks for the info. So hopefully nothing in the traction motor inverter circuitry, or any other load, can result in the pre-charge current
being greater than an amp or the pre-charge resistor will be damaged. Obviously a delay in the VCM de-activating the pre-charge
relay, or its hanging, could be problematic. You've have thought that the pre-charge resistor would have been fused, i.e. given the
complexity to replace it or a worst case failure mode analysis. Its failure, notwithstanding a DIY effort, is very costly as previously noted.
Leaf SL MY 9/13: 66K miles, 50 Ahrs, 5.2 miles/kWh (average), Hx=70, SOH=78, L2 charges to 100% > 1000, max battery temp < 95F (35C), min discharge point > 20 Ahrs