Comparison of internal parameters varied by environmental tests between high-power series/parallel battery packs with different shapes

Abstract

This study elaborately analyzes the lithium-ion battery pack in series and parallel connection installed in space applications through environmental tests that typically composed of three tests: half-sine shock, sine vibration and random vibration. These tests are well conducted based on the internal certification standard and the space industry standard. Above all, from basic equivalent electrical circuit modeling of the high-power 18650-HE4 cell based series/parallel battery packs of 4S4P with rectangular and cube types, some internal parameters were minutely extracted and compared to check which environmental test adversely affects the battery pack’s electrochemical characteristics and its electrical performance. Moreover, maximum/minimum cell voltages and their differences measured in four series point and internal temperature measured in five points inside the two battery packs are compared. For reference, in order to analyze the impact of the battery pack clearly, this study further analyzed some single cells with various impacts through identical environmental test profiles. Above analyses and comparisons can help to get a solution for finding a suitable shape for space application with a parameter change rate according to the different shape of the battery pack. In particular, the necessity of a modified equivalent electrical circuit modeling of the battery pack varied by environmental tests can be sufficiently suggested. Accurate information on internal parameters of the cell and battery pack contributes to the high-fidelity state-of-charge (SOC) estimation and state-of-health (SOH) prediction in vibration and shock environments such as electric vehicle (EV), satellites and space-launch vehicles.