Patent ID: 8704496

Claim:
A charge control system, comprising: an electric power storage device configured to be charged by using alternating current electric power supplied from an external commercial power source; a voltage detection section configured to detect a voltage V across the electric power storage device; a charged state estimation value setting section configured to set a charged state estimation value Vf based on the voltage V across the electric power storage device; and a charged state estimation section configured to estimate a charged state of the electric power storage device based on the charged state estimation value Vf, wherein the charged state estimation value setting section includes: an initial state setting section which divides a charging period of the electric power storage device into a first half charging period, which is set as a predetermined period from beginning of charging, and a second half charging period subsequent to the first half charging period, and sets a charged state estimation value Vf for the first half charging period as a value VfL of an initial state; a variation suppression coefficient setting section which sets a variation suppression coefficient t to be a smaller value in response to: (1) an amount of a voltage drop, which temporarily occurs in response to a variation in power supplied from the external commercial power source, or (2) a number of voltage drops, based on rising characteristics of the voltage V across the electric power storage device that rises with charging when there is no variation in power supplied from the external commercial power source in the first half charging period, the variation suppression coefficient having a value that is not equal to zero or one; and a variation suppression section which sets a charged state estimation value Vf for the second half charging period using Vf=(1−t)*VfL+t*V, using the variation suppression coefficient t which is set by the variation suppression coefficient setting section.