SLYY218 December   2022 BQ79731-Q1

 

  1.   At a glance
  2.   Authors
  3.   3
  4.   The working principle of a BMS and industry trends
  5.   New battery chemistries
  6.   Wireless BMS
  7.   Advanced estimations of battery capacity and battery health
  8.   A detailed look at the cell supervisor unit (CSU)
  9.   Traditional vs. intelligent battery junction box (BJB)
  10.   A detailed look at the BJB
  11.   A detailed look at the battery control unit (BCU)
  12.   Creating a complete battery test environment ecosystem
  13.   Conclusion
  14.   Additional resource

Advanced estimations of battery capacity and battery health

An accurate estimation of a battery’s remaining charge has a direct effect on the remaining driving range. Even though battery cell manufacturers provide the nominal capacity of the battery, it changes over time. Some important factors that cause battery capacity to fade include elevated temperature, cycling (usage), depth of discharge patterns and aging. These factors require continuous estimation of the battery capacity for an accurate estimation of the state of charge.

Accurate measurement of a battery’s health determines whether the drivers will have to replace the battery or wait until an explicit and hazardous cell failure event occurs.

Effective synchronization of voltages and currents helps enable precise state-of-charge, state-of-health and electrical impedance spectroscopy (EIS) calculations that results in optimal utilization of the battery. For more information, see the technical article How to design an intelligent battery junction box for advanced EV battery management systems.