Abstract: An estimation method includes: performing, for each different degree of degradation, regression analysis between a first value and a second value, wherein the first value is related to one or more reference feature points on a differential curve of a charging-discharging curve indicating a voltage value with respect to integrated current amount of a reference storage battery, and the second value is at least one of a capacity value of the reference storage battery and an internal resistance value of the reference storage battery; and estimating at least one of a capacity value of a target storage battery and an internal resistance value of the target storage battery, based on a result of the regression analysis and a third value related to one or more target feature points on a differential curve of a charging-discharging curve of the target storage battery.

Abstract: A secondary battery capacity measuring system that estimates maximum capacities of other cells using characteristics of a deteriorated cell even when a charging process in the deteriorated cell having a smaller maximum capacity than the other cells in cells constituting a battery module ends and data for measuring the maximum capacities of the other cells cannot be acquired is provided.

Abstract: A secondary battery capacity measurement system includes a data convertor, an SOC computer, and a maximum capacity computer. The data convertor determines a partial derivative characteristic curve of a capacity-to-voltage derivative over voltage, the partial derivative characteristic curve indicating a characteristic of a capacity-to-voltage derivative, from a set of historical data of time-sequentially-measured values of voltage and current. The SOC computer computes a difference between the partial derivative characteristic curve and a reference derivative curve indicating a reference characteristic of the capacity-to-voltage derivative, and fits the partial derivative characteristic curve to the reference derivative curve by reducing the difference to estimate an SOC. The maximum capacity computer estimates a maximum value of capacity, from the partial derivative characteristic curve and the reference derivative curve.

Abstract: A secondary battery capacity measuring system that estimates maximum capacities of other cells using characteristics of a deteriorated cell even when a charging process in the deteriorated cell having a smaller maximum capacity than the other cells in cells constituting a battery module ends and data for measuring the maximum capacities of the other cells cannot be acquired is provided.

Abstract: A secondary-battery maximum-capacity measuring apparatus, includes: a current dependency processing unit configured to convert an inter-terminal voltage and an open cell voltage of a secondary battery into values without depending on a load current based on an amount of change in relative value of a voltage during a time period when a constant current is drawn from the secondary battery; and an error calculation unit configured to compute errors of the inter-terminal voltage and the open cell voltage of the secondary battery, the inter-terminal voltage and the open cell voltage being converted by the current dependency processing unit.

Abstract: A secondary battery capacity measurement system includes a data convertor, an SOC computer, and a maximum capacity computer. The data convertor determines a partial derivative characteristic curve of a capacity-to-voltage derivative over voltage, the partial derivative characteristic curve indicating a characteristic of a capacity-to-voltage derivative, from a set of historical data of time-sequentially-measured values of voltage and current. The SOC computer computes a difference between the partial derivative characteristic curve and a reference derivative curve indicating a reference characteristic of the capacity-to-voltage derivative, and fits the partial derivative characteristic curve to the reference derivative curve by reducing the difference to estimate an SOC. The maximum capacity computer estimates a maximum value of capacity, from the partial derivative characteristic curve and the reference derivative curve.

Abstract: A secondary-battery maximum-capacity measuring apparatus, includes: a current dependency processing unit configured to convert an inter-terminal voltage and an open cell voltage of a secondary battery into values without depending on a load current based on an amount of change in relative value of a voltage during a time period when a constant current is drawn from the secondary battery; and an error calculation unit configured to compute errors of the inter-terminal voltage and the open cell voltage of the secondary battery, the inter-terminal voltage and the open cell voltage being converted by the current dependency processing unit.

Abstract: There is provided a battery characteristic evaluator configured to identify a circuit constant of an equivalent circuit model based on a current-voltage characteristic of a battery. The battery characteristic evaluator includes: a current waveform divider configured to divide a certain current waveform into a plurality of step functions with a plurality of infinitesimal time intervals and output the step functions; and a circuit constant optimizing unit configured to calculate the optimized circuit constant of the equivalent circuit model, based on the step functions, a measured voltage value, and equivalent circuit model data.