Abstract: A device includes an interface and a processor. The interface receives information for a parameter indicative of a status of a battery. The processor calculates a remaining capacity of the battery, calculates a capacity ratio of the calculated remaining capacity to a capacity reference of the battery, compares the parameter with a parameter reference to generate a first comparison result, compares the capacity ratio with a ratio reference to generate a second comparison result, sets an amount according to the first and second comparison results, and changes the calculated remaining capacity by the amount.