New Approach to Assembling Used 18650 Cells by the DBSCAN Clustering Algorithm

Rezoug, Mohamed Redha; Khettache, Laid; Benmakhlouf, Abdeslam; Djarah, Djalal

doi:10.22060/eej.2026.24892.5788

New Approach to Assembling Used 18650 Cells by the DBSCAN Clustering Algorithm

Document Type : Research Article

Authors

Mohamed Redha Rezoug

Laid Khettache

Abdeslam Benmakhlouf

Djalal Djarah

Department of Electrical Engineering, Faculty of Technology, Kasdi Merbah University – Ouargla 30000, Algeria

10.22060/eej.2026.24892.5788

Abstract

This study presents a diagnostic and regrouping approach for used 18650 lithium-ion cells using the DBSCAN clustering algorithm. A total of 154 cells were recovered from discarded laptop batteries. After electrical testing (constant-current discharge measuring capacity, voltage, and internal resistance), 120 cells (78%) were identified as healthy and suitable for reuse. The DBSCAN algorithm (eps=0.3, min_samples=10) was applied to cluster these 120 cells based on their electrical characteristics. The algorithm successfully formed three homogeneous clusters of 40 cells each. These clusters were assembled in a 3S40P configuration (three parallel packs of 40 cells connected in series) to form a second-life battery of approximately 81 Ah capacity at 10.9 V. Comparative analysis shows that DBSCAN outperforms K-means and hierarchical clustering for this application, achieving a silhouette coefficient of 0.62 versus 0.48 for K-means. The proposed method achieves a 78% cell recovery rate, demonstrating its effectiveness for battery recycling and second-life applications.

Keywords

DBSCAN

Reconditioning

Recycling

lithium battery

18650 cell

Clustering

Subjects