A Method for Quantitative Detection of the Micro-Short Circuit in Lithium-Ion Battery Packs Under Equilibrium Condition

The early detection and control of the Li-ion battery micro-short circuit can effectively avoid battery safety accidents. Battery equalization affects the inconsistency between cells, which makes micro-shorts in the cells more insidious. For this purpose, this paper proposed a method to quantify the battery micro-short circuit based on the equilibrium electric quantity(EEQ). First, we used the cell with the lowest voltage at the start of two adjacent equalizations as the marked cell and calculated the EEQ of the other cells. We analyzed the relationship between the EEQ and the leakage of the marked battery and proposed a method to quantify the marked battery. Then, we offered solutions for the effects caused by inconsistencies between normal cells and the presence of cells with abnormal capacities. Finally, we verified the applicability of this micro-short circuit diagnosis method for different short circuit levels, different operating conditions, different equalization strategies, and the presence of the abnormal capacity cell experimentally. The experimental results showed that the average error in the short-circuit resistance estimated for multiple test cases was 3.65%. This method is suitable for battery management systems because it does not require robust computational power and has high accuracy and robustness.