Evaluation of Lithium-Ion Battery Pack Capacity Consistency Using One-Dimensional Magnetic Field Scanning

The capacity inconsistency among commercial lithium-ion battery packs is an important factor affecting their service life. However, there is still a lack of detection methods to accurately test the capacity consistency of lithium-ion battery packs at cell level. To solve this problem, a non-destructive testing method for capacity consistency of lithium-ion battery pack based on 1-D magnetic field scanning is proposed in this article. First, a magnetic field simulation model and measurement setup of lithium-ion battery are developed to study the principle of detection technology. On such basis, a capacity consistency evaluation method of lithium-ion battery packs is proposed using magnetic field feature extraction and k-nearest neighbors (k-NNs), and the effectiveness of the method is verified by experimental testing. Finally, measuring factors affecting magnetic field distribution features and practicality of the method are discussed using multi-cells' magnetic field simulation models. The results show that the proposed method can accurately diagnose the capacity consistency of the tested battery pack, which provides a basis for battery pack performance testing and maintenance.