Patent ID: 8886479

Claim:
A charge state detecting device for a battery pack having a plurality of battery cells connected to one another in series, said plurality of battery cells being divided into a plurality of battery blocks each having at least one battery cell, the charge state detecting device comprising: a stored charge amount estimating unit configured to calculate a plurality of stored charge amount estimate values respectively corresponding to said plurality of battery blocks, based on respective state detection values at said plurality of battery blocks; and a total stored charge amount setting out unit configured to set a total stored charge amount estimate value of the battery pack based on said plurality of stored charge amount estimate values, said total stored charge amount setting unit being configured to: set said total stored charge amount estimate value to be higher than a control upper limit value in a first case where a maximum value of said plurality of stored charge amount estimate values is higher than said control upper limit value; set said total stored charge amount estimate value to be lower than a control lower limit value in a second case where a minimum value of said plurality of stored charge amount estimate values is lower than said control lower limit value; and set said total stored charge amount estimate value at a value within a control range defined to be not less than said control lower limit value and not more than said control upper limit value, based on a distribution of said plurality of stored charge amount estimate values at present in a third case where all of said plurality of stored charge amount estimate values are within said control range, said total stored charge amount setting unit being configured to calculate a variation amount in accordance with a difference between said maximum value and said minimum value and being configured to determine a parameter in accordance with a ratio of a second value to a first value, said first value being obtained by subtracting said variation amount from a control width representing a width of said control range, said second value being obtained by subtracting said variation amount and said control lower limit value from said maximum value, said parameter indicating where said plurality of stored charge amount estimate values at present are located in said control range, said total stored charge amount setting unit being configured to set said total stored charge amount estimate value in accordance with a total of a multiplication value of said parameter and said control width and said control lower limit value.