STUDY ON SECOND-LIFE ELECTIC VEHICLE BATTERIES FOR STATIONARY BATTERY ENERGY STORAGE AS AN UNINTERRUPTIBLE POWER SUPPLY

• Main Author: Zuhdi Bardani, Barkah
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86779
• Institution: Institut Teknologi Bandung

The increasing number of electric vehicles in Indonesia from year to year will create new challenges when the lithium-ion batteries used in these vehicles degrade. Once the State of Health (SOH) reaches 70-80%, the batteries are considered unsuitable for electric vehicles application because they are no longer efficient. After reaching this point, the retired batteries can either be disposed of, recycled, or repurposed for applications that do not require high performance, often referred to as second-life applications as stationary battery energy storage systems (SBES). Customers of PT PLN (Persero), particularly on the island of Java, still experience power outages, as indicated by the System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI) parameters. Given the potential to utilize retired electric vehicle batteries in battery energy storage systems to address disruptions in PT PLN's electricity supply, this research aims to provide an overview of how these retired batteries can be repurposed in Uninterruptible Power Supply (UPS) applications. The research method includes collecting test materials and conducting assessments of battery conditions based on parameters such as Open Circuit Voltage (OCV), internal resistance testing, capacity testing, and battery degradation testing. Testing at the module level with Battery Management System (BMS) is sufficient to illustrate the overall condition of the battery; however, cell-level testing is still recommended to ensure the condition of all cells within the module. Second-life battery categorization can be based on the State of Health (SOH) value obtained from capacity testing. The safe operating range for LFP IFR32700 batteries is recommended to be between 2.4V–3.5V, with charge and discharge currents below 0.2C. Batteries with an SOH of 75-79% are still suitable for use in UPS application. The recommended CDT system design includes a 48V specification with a capacity range of 4.8–14.4 kWh, equipped with a Battery Management System (BMS), a pure sine wave inverter operating at 220V with a power rating of 3000 watts, and a charge controller with a Constant Current Constant Voltage (CC-CV) charging method. Keywords: second-life batteries, lithium-ion, energy storage, uninterruptible power supply (UPS), battery degradation, electric vehicles (EVs).