Patent ID: 8847543

Claim:
A secondary battery charging system, comprising: a secondary battery charging device that charges a secondary battery and controls charging of the secondary battery, the secondary battery having a protection timer that counts a first elapsed time from a start of the charging and is pre-set a charging time, and a function to stop a charging operation when the first elapsed time exceeds the charging time; and a power generation device that generates a charging current as a charging power source of the secondary battery; wherein the secondary battery charging device includes a charging switch that performs a control of determining whether to supply the charging current from the power generation device to the secondary battery, a time management timer portion, in which are pre-set a stop time that is shorter than the charging time and a determination time required for the secondary battery to detect that the charging current from the power generation device is cut off, the time management timer portion counting a second elapsed time starting from a point at which the charging switch becomes conductive and performing a charging stop determination that determines whether the second elapsed time matches the stop time, and also counting a third elapsed time starting from a point at which the charging switch is cut off and performing a charging start determination that determines whether the third elapsed time matches the determination time, and a charging control portion that causes the charging switch to be conductive or cut off based on results of the charging stop determination and the charging start determination.