Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (7): 2271-2281.doi: 10.19799/j.cnki.2095-4239.2023.0235

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Testing and analysis of safety characteristic-parameter thresholds for power batteries under different conditions

Lei ZONG(), Long CHEN, Feng ZHU(), Guogang LIU, Yaqing SUN, Haishu DONG   

  1. Beijing National New Energy Vehicle Technology Innovation Center Co. , Ltd. , Beijing 100174, China
  • Received:2023-04-18 Revised:2023-06-09 Online:2023-07-05 Published:2023-07-25
  • Contact: Feng ZHU E-mail:zonglei@nevc.com.cn;zhufeng@nevc.com.cn

Abstract:

The safety and reliability of a vehicle depend on the consistency of the safety characteristic parameters of its power battery system. To analyze the threshold and causes of these parameters throughout the lifespan of the battery, this study conducts the cloud data analysis and high/low temperature charging and discharging test on retired battery systems, as well as the extreme condition test on battery cells. The maximum differences in voltage and temperature serve as indicators to evaluate parameter thresholds. The results show that the voltage difference threshold of a vehicle gradually increases with the service time. The main reason for a large voltage difference is the high discharging current during the driving process. Owing to the low state of charge, the experimental voltage difference is larger compared to the difference in voltage obtained from cloud data. The temperature difference threshold of the battery system is closely related to the ambient temperature. Although the maximum temperature difference does not appear during a single charging-discharging process in low-temperature conditions, the continuous driving or charging process in winter can increase temperature difference. After the overtemperature test of new and degraded batteries, the open circuit voltage of the degraded battery was directly reduced to 0 V, and its internal resistance and thickness increased substantially, indicating that the safety performance of a degraded battery deteriorated under extreme conditions. With the testing and analysis results of safety characteristic parameters under different conditions, this study contributes to the consistency analysis and the development of warning strategies for power battery systems.

Key words: battery system, characteristic parameter, threshold, voltage difference

CLC Number: