What is VECU received BMS derate flag? Where and What to check.

 

VECU received BMS Derate Flag

The Battery Management System (BMS) is responsible for monitoring and controlling the battery pack to ensure safe and efficient operation in any ev vehicle.

 When it detects conditions that may affect battery health or vehicle performance, it can send a derate flag to the Vehicle Electronic Control Unit (VECU) over the Controller Area Network (CAN) bus.

This derate flag instructs the vehicle to reduce power output, limiting acceleration, regenerative braking, or other power-intensive functions. The derate condition is temporary and will be lifted once the issue that triggered it is resolved.

 Possible reasons for the BMS derate flag to be triggered:

High battery temperature: The BMS may derate the power output to prevent the battery from overheating.

Low battery voltage: The BMS may derate the power output to prevent the battery from being over-discharged.

High current: The BMS may derate the power output to prevent the battery from being damaged by excessive current draw.

Cell imbalance: The BMS may derate the power output to prevent further imbalance between the battery cells.

Other BMS faults: The BMS may derate the power output due to other faults detected by the BMS, such as a sensor failure or a communication error.

 

What will the VCEU do after receiving derate flag CAN messages from BMS?

Reduce the power output of the vehicle: This may involve limiting the motor power, disabling certain features, or even reducing the vehicle's speed.

Display a warning message in the Cluster: This will inform the driver of the issue and the reduced performance of the vehicle.

Store a diagnostic trouble code (DTC): This will help technicians diagnose the issue.

BMS Derate Flag is a critical signal that protects the battery from damage. By diagnosing the exact cause (temperature, voltage, current, or internal faults) we can troubleshoot the problem within the EV Vehicle.