METHOD FOR ESTIMATING REMAINING USABLE TIME OF BATTERY AND APPARATUS FOR MONITORING REMAINING TIME

摘要

PROBLEM TO BE SOLVED: To estimate and monitor remaining usable time of a battery by measuring a falling ratio of voltage of the battery with time, obtaining a differential coefficient of relation between voltage and remaining usable time, and utilizing the fact that the falling ratio is equal to the differential coefficient. SOLUTION: The apparatus is provided with a voltage comparison means 12 for comparing measured voltage and stored voltage in a memory, a falling ratio calculation means 13 for calculating falling ratio of the voltage, a remaining usable time calculation means 14, a warning generation means 16 for warning of the remaining usable time, and a memory 17 for storing a constant indicating a discharging characteristic and a reference remaining time. When a voltage measured by the measuring means 12 is lower than a limit threshold value of an appliance, a warning is directly generated. If the measured voltage is higher than the threshold value, a falling ratio is calculated by the calculation means 13 from the arrange of the voltage and time interval estimating the voltage change from the memory 17, thereby to calculate the remaining time. The remaining time is compared with the reference remaining time stored in the memory. If the remaining time is longer than the reference time, no warning is generated. On the other hand, if the remaining time is shorter than the reference time, a warning is generated and a power source line from the battery to the appliance is shut. Accordingly, the remaining time can be estimated and monitored from using conditions of the battery.