Thermal Variation on 18650 Cylindrical Cells under Different Testing Arrangement

Abstract

Cylindrical cell, especially with the 18650 format, is widely used for power electronics and electric vehicle. The cell's performance is strongly dictated by the current rate of charge/discharge and the cell temperature. The former is relatively easy to gauge because the value is constant for a certain period. Therefore, the cell performance can be mapped with respect to the current rate. However, the cell temperature varies temporally and dimensionally, making mapping cell performance concerning temperature difficult. This study employs a comprehensive thermal approach, with the aim to evaluate the degree of thermal variation with respect to various testing temperatures and cell arrangements conducted in a thermal chamber. Thermal measurements are measured, such as cell surface temperature at various cell locations. The experimental results provide an insight that different testing arrangements in which the cell is suspended vertically and horizontally do not alter the temperature variation of the cell significantly. Nevertheless, temperature difference up to 3oC is manifested along the cell surface, which happens at 5oC ambient temperature. This analysis highlights that cell temperature on the surface of 18650 cell is highly non-uniform, and the data could be further used to facilitate the cell's cooling system in for cells in this nature.