What is Battery Charge Monitoring in Battery Management System?

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Editorial Team - everything PE

May 15, 2024

Battery Monitor from Renogy

Battery monitoring or cell monitoring is the monitoring of each cell in the battery pack to ensure that they are operating within the safe operating range. It is a crucial component of the battery management system (BMS) that continuously tracks the battery's state of charge (SoC), state of health (SoH), capacity, remaining operating time, charge consumption and charging cycles by monitoring each cell’s voltage, current, and temperature.

Battery charge monitoring in a BMS is usually done using a fuel gauge monitor that tracks the charge flowing into and out of the battery pack. The key aspects of battery charge monitoring are:

  • Measure charge flow: The fuel gauge monitor calculates the charge flow by multiplying the current and time. This is usually done using a 16-bit ADC to measure the voltage across a sensing resistor, providing a wide dynamic range at a fast rate.
  • Calculate battery values: Based on the charge flow measurements, the BMS calculates various battery parameters such as - energy delivered since the last charge cycle, internal impedance to estimate open-circuit voltage, charge in Ah delivered or contained in each cell (Coulomb counting), total energy delivered and operating time since battery started being used, and the number of charge-discharge cycles.
  • Determine state of charge (SoC): The BMS uses the charge flow measurements to determine the remaining charge or state of charge of the battery pack.
  • Monitoring individual cell voltages: The BMS measures the voltage of each cell to ensure they operate within normal levels during charging and discharging. Cell voltage monitoring is a standard feature to assess battery health.

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