| 摘要 |
PROBLEM TO BE SOLVED: To improve estimation accuracy by measuring the current value and voltage value of a battery in a fixed cycle, approximating a plurality of points with a specific curve on a plane with current and voltage as two axes, and estimating the residual capacity of a battery on the basis of a representative. SOLUTION: A battery 1 is charged and discharged by a charger-discharger 2, and an ammeter 4 for measuring the current is connected to a voltmeter 5 for measuring voltage. The ammeter 4 and voltmeter 5 are connected to a device 6 to estimate the residual capacity of the battery 1. The current value Ik and voltage value Vk (k=1 to n) of the battery 1 are measured in a specified cycle and classified into a first group with the current value Ik increased from the current value Ik-1 acquired one cycle before, and a second group with the current value Ik decreased. On a plane with current and voltage as two axes, a plurality of sets belonging to the first group are approximated with a first parabola, and a plurality of sets belonging to the second group are approximated with a second parabola. The residual capacity of the battery 1 is estimated based on the average point of a focus of the first parabola and a focus of the second parabola.
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