Battery residual capacity measuring apparatus and method for measuring open-circuit voltages as the battery starts and stops supplying power

摘要

While a power source is being supplied from a sub-battery by a voltage-current change trend calculating section, the voltage-current change trend calculating section collects currents from a battery and terminal voltages. A voltage-current approximate straight line calculating section obtains an approximately linear function, and a battery residual capacity calculating section obtains a residual capacity voltage based upon the approximately linear function and open-circuit voltages. A current storage stop discriminating section integrates the currents while the residual capacity voltage is lower than a previous residual capacity voltage, and when supplying from the sub-battery is stopped, obtains total capacity according to the open-circuit voltages at the stop and supplying and according to the integrated currents.