Review of Equalization Techniques Applied to Second-Life EV Battery Packs and Their Efficiency

Electric Vehicles (EV s) are becoming increasingly popular, and as a result, second-life EV batteries are being produced in copious quantities. When the EV battery capacity falls below 80% of its original capacity, it is no longer considered suitable for use in EVs. The Second Life (SL) EV battery issue is becoming more pressing with the rising popularity of EVs. One of the most popular uses for these batteries is in stationary energy storage systems, but to do so efficiently, it is crucial to ensure that every cell within the battery stack is charged and balanced properly. This paper provides an overview of different equalization techniques that have been adopted or are being researched for second-life EV batteries. It also provides information on which method is more efficient for measuring the efficiency of the equalizer. This paper details the advantages and disadvantages of each technique and evaluates their effectiveness in balancing cell charges. Furthermore, this paper highlights some unresolved challenges and areas for further research in this field.