Stuck-closed diagnosis method and battery system using the same

A battery system comprising:

• a plurality of battery packs;
• a plurality of positive relays, each respective battery pack including a respective positive relay, connected between a positive electrode and a positive link of the respective battery pack;
• a plurality of negative relays, each respective battery pack including a respective negative relay, connected between a negative electrode and a negative link of the respective battery pack;
• and
• a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs in a one-to-one correspondence,
• wherein each pack BMS of the plurality of pack BMSs, in an opening control condition of the plurality of positive relays and the plurality of negative relays, is configured to determine at least one positive relay and at least one negative relay to which at least one battery pack current among a plurality of battery packs flows to be stuck-closed when a battery pack current of any pack BMS's corresponding battery pack is larger than a third threshold current.

A stuck-closed diagnosis method for a plurality of positive relays, each respective battery pack including a respective positive relay, connected to a positive electrodes of the respective a battery pack and a negative relay of the respective battery pack, the method comprising:

• configuring each pack BMS of a plurality of pack BMSs connected to the respective battery pack to perform:
• comparing a voltage difference between terminals of each of the plurality of positive relays with a first threshold voltage in an opening control condition and each of the plurality of negative relays;
• sequentially closing the plurality of negative relays one by one when at least one of the voltage difference is less than the first threshold voltage;
• comparing a respective battery pack current flowing through each of the plurality of battery packs with a first threshold current;
• and
• determining at least one positive relay to be stuck-closed when at least one of a plurality of battery pack currents flowing through each of the plurality of battery packs is greater than a first threshold current.