SIGN DETECTION SYSTEM, SIGN DETECTION METHOD, AND SIGN DETECTION PROGRAM

In a sign detection system, a battery data acquisition unit acquires battery data including current data obtained by periodically measuring a current flowing through a battery pack. When the current data in a period of charging the battery pack by a charger include a section temporarily having a current value of zero, a determination unit determines that the occurrence of the section having the current value of zero is a sign of unavailability of the battery pack.