PURPOSE: To improve measuring accuracy by providing another voltage measuring means for measuring the terminal voltage of another storage battery so as to measure a ripple component separately, and computing for eliminating the ripple component. CONSTITUTION: Before a predetermined current is made to flow in a first storage battery 31 by a current generating means 130, the terminal voltage of the first storage battery 31 and the terminal voltage of second storage battery 32 are separately measured by first voltage measuring means 120 and second voltage measuring means 121. When the predetermined current is made to flow in the first storage battery 31 by the current generating means 130, the terminal voltage of the first storage battery 31 and the terminal voltage of the second storage battery 32 are separately measured by the first voltage measuring means 120 and the second voltage measuring means 121. A computing/controlling means 140 conducts subtraction correction of the variation of the terminal voltage of the first storage battery 31 measured through the first voltage measuring means 120 by using the variation of the terminal voltage of the second storage battery 32 measured through the second voltage measuring means 121. The internal resistance of the first battery 31 is obtained thereby.
展开▼
