Sustainable energy storage: a 60 v/2.5 kwh system powered by second-life electric vehicle batteries

Abstract

This work presents the development and experimental validation of a second-life battery energy storage system (SLBESS) constructed from Renault Kangoo electric vehicle modules with approximately eight to ten years of prior operation. Motivated by the growing demand for sustainable and low-cost storage solutions, the study investigates the technical feasibility of repurposing these modules for stationary applications. The main objective was to characterize the electrochemical condition of the recovered cells and implement their integration into a 60 V, 40 A energy storage architecture. The methodology comprised State of Health (SoH) assessment, internal resistance evaluation through HPPC testing, the design of an electrical architecture incorporating an active protection strategy based on a BMS and pre-charge circuitry, and the construction of a mechanical enclosure with forced thermal management. Experimental results demonstrated consistent and reliable performance. Under controlled cycling, the system delivered an effective capacity of 46.1 Ah, a round-trip energy efficiency of 93.36%, and a coulombic efficiency of 99.84%. Thermal stability was maintained below 31°C during continuous discharge, and the protection logic responded correctly to induced fault conditions. These findings confirm the technical viability of the developed SLBESS and its potential applicability in low-voltage distribution networks, contributing to extended battery lifecycle utilization and supporting the transition toward more resilient and sustainable energy systems.