BMS Operation

Battery Management System (BMS) 

1. Overview

The BMS is responsible for monitoring and controlling various aspects of battery performance to extend battery life, maintain safety, and optimize energy usage. It interfaces with both the battery pack and external systems (e.g., charger, load controller, vehicle control unit).

2. Key Functions of BMS

a. Monitoring

• Voltage Measurement: Continuously measures individual cell voltages and pack voltage.
• Current Measurement: Tracks charge/discharge current using shunt or Hall sensors.
• Temperature Monitoring: Monitors cell/module temperature via thermistors or sensors.

b. Protection

• Overvoltage/Undervoltage Protection: Prevents cells from exceeding voltage limits.
• Overcurrent Protection: Detects abnormal current levels during charge/discharge.
• Overtemperature Protection: Prevents operation in unsafe thermal conditions.
• Short Circuit Detection: Rapid detection and response to short circuits.

c. Balancing

• Passive Balancing: Discharges higher-voltage cells through resistors to equalize cell voltages.
• Active Balancing: Transfers charge from higher-voltage to lower-voltage cells for efficiency.

d. State Estimation

• State of Charge (SOC): Estimates remaining battery capacity.
• State of Health (SOH): Evaluates battery aging and performance degradation.
• State of Power (SOP): Predicts the available power for load/charging.

e. Communication

• Interfaces with external controllers using CAN, UART, SPI, or I2C protocols.
• Sends real-time data, diagnostics, and alerts to higher-level control systems.

f. Logging and Diagnostics

• Logs events, faults, and operational data.
• Supports fault detection and root cause analysis.

3. Operational Modes

• Normal Operation: Manages safe and efficient energy flow under nominal conditions.
• Charging Mode: Controls charging current and voltage, ensures balance and safety.
• Discharging Mode: Manages energy delivery to load while protecting battery integrity.
• Idle Mode: Minimal power draw, monitors key parameters.
• Fault Mode: Activates safety mechanisms and communicates error conditions.

4. Safety Features

• Redundant monitoring for critical parameters.
• Hardware protection circuits for extreme events.
• Emergency cut-off using relays/contactors.