Balanced capacity-based quantitative method for detecting internal short circuits in Lithium-ion battery modules

Internal short circuits in lithium-ion batteries present a significant risk of thermal runaway. This study introduces a precise quantitative method for diagnosing internal short circuits in lithium-ion batteries based on balanced capacity. By calculating the theoretical balanced capacity of each cell in the absence of an internal short circuit and comparing it with the actual balanced capacity measured by the balancing system, the internally short-circuited cell can be identified, and the internal short-circuit resistance can be determined. Experimental validation is conducted in both active and passive balancing scenarios, covering various aging conditions and a wide range of internal-short-circuit resistance values (55-330Ω). Results show that the proposed method can accurately evaluate the leakage current caused by internal short circuits, with estimation errors bounded by ±1 mA for typical load profiles. Notably, this method does not require restrictions on battery operating conditions or additional sensors, making it a cost-effective solution that can be easily integrated into existing battery management systems. This provides an economical and efficient approach for detecting internal short circuits in battery packs.