METHOD OF ESTIMATING INTERNAL DEGRADATION STATE OF DEGRADED CELL, AND MEASUREMENT SYSTEM OF CARRYING OUT THE METHOD

In a method of estimating an internal degradation state of a degraded cell, a measurement system calculates a target capacity characteristic curve by differentiating current capacity by voltage on a target charge curve of a target battery. Further, the method obtains changes of parameters of different types based on a fitting operation that fits the curve and a reference capacity characteristic curve calculated from reference data. In the fitting operation, whichever of low current capacity regions and high current capacity regions of the curve and the curve have a stronger correlation are fit first and whichever of them have a weaker correlation are fit later.