Battery management method and battery system using the same including a plurality of slave battery management systems and a master battery management system

A management method of a battery system including a plurality of battery packs, a plurality of slave battery management systems (BMSs), and a master battery management system (BMS) connected to the plurality of slave BMSs by wireless communication, comprising:

• determining whether a wireless communication failure occurs between the master BMS and at least one of the plurality of slave BMSs;
• receiving road condition information where a vehicle equipped with the battery system is currently positioned if the wireless communication failure occurs;
• determining whether the vehicle is on a road capable of causing a cell overvoltage/low voltage based on the road condition information;
• setting a first failure confirmation time if a current position of the vehicle is on the road capable of causing the cell overvoltage/low voltage;
• setting a second failure confirmation time if the current position of the vehicle is not located on the road capable of causing the cell overvoltage/low voltage;
• and
• entering a safety mode if a wireless communication failure section from a time when the wireless communication failure occurs to a current time reaches the first failure confirmation time or the second failure confirmation time,
• wherein the second failure confirmation time is longer than the first failure confirmation time.