BATTERY BANK UNIT, REMAINING CHARGE TIME CALCULATION METHOD, AND REMAINING CHARGE TIME CALCULATION PROGRAM

A battery bank unit includes: a first battery bank and a second battery bank that are connected in parallel to each other; and a control apparatus that performs collective charge for collectively charging the first battery bank and the second battery bank, performs first bank charge for charging only the first battery bank after the collective charge, and performs second bank charge for charging only the second battery bank after the first bank charge. The control apparatus calculates remaining time to complete charge of the battery bank unit based on a temperature of the battery bank unit at a start of the collective charge.