BATTERY RESIDUAL CAPACITY MEASURING DEVICE

摘要

PURPOSE: To provide a battery residual capacity measuring device which can accurately obtain residual capacity of a battery even when load fluctuation is abrupt. CONSTITUTION: Detection voltage at a terminal of a battery 3 and detection current supplied to a load are detected by using a voltage sensor 9 and a current sensor 7. A voltage-current changing tendency calculating part 21 reads the detection voltage and the detection current of the battery 3 at each lapse of a fixed time and stores the dispersion data in a memory 33. Based on the dispersion data in this collection period, a voltage-current approximate straight line calculation part 29 finds a voltage-current approximate straight line function during the period in which a specified number of detection voltages and detection currents are collected. A battery residual capacity calculation part. 23 finds a residual capacity based on positional relationships of the voltage-current approximate straight line function respectively to a voltage-current axis and to the voltage-current approximate straight line function at the time of driving a load with full charge.