Vehicle battery pure resistance measuring method and apparatus

摘要

PROBLEM TO BE SOLVED: To provide a method and a device for measuring battery pure resistance for a vehicle capable of measuring pure resistance of a battery even during a use of a vehicle. SOLUTION: A terminal voltage and a discharge current when a discharge current flows from a battery are periodically measured by a voltage.current measuring means 23a-1, and a first approximate curve formula for voltage- current characteristics to an increasing discharge current and a second approximate curve formula for a voltage-current characteristics to a decreasing discharge current are determined by an approximate curve formula calculating means 23a-2. A computing means 23a-3 determines two linear formulas indicating a change of synthetic resistance presented by the battery to the increasing discharge current and the decreasing discharge current by respectively differentiating the two approximate secondary curve formulas. Two values corresponding to the maximum values of the determined the discharge currents of the two linear formulas are determined. A value obtained by multiplying a value, obtained by adding the determined two values, by 1/2 is measured as pure resistance of the battery.