Voltage detection device, voltage detection method, abnormality determination device, abnormality determination method, and battery pack system

A voltage detection method of detecting a voltage of a battery stack of a battery pack comprising a plurality of battery stacks, each of which having a plurality of battery cells connected in series, and a connection member configured to electrically connect the plurality of battery stacks, the voltage detection method comprising:

• controlling a plurality of switches, each of which having one end connected to a terminal of each of the plurality of battery stacks and the other end connected to the capacitor;
• detecting a voltage of the capacitor;
• when discharging the capacitor, selecting a discharging path comprising the connection member and the capacitor, and
• determining whether an abnormality has occurred in the battery pack or at least one of the plurality of switches, in correspondence to at least one of a voltage of the capacitor after charging and a voltage of the capacitor after discharging.

A abnormality determination device configured to determine whether an abnormality has occurred in a battery pack comprising a plurality of battery stacks, each of which having a plurality of battery cells connected in series, and a connection member configured to electrically connect the plurality of battery stacks, the abnormality determination device comprising:

• a capacitor connected to the plurality of battery stacks in parallel;
• a detection unit configured to detect a voltage between both ends of the capacitor;
• a charging path selection unit that selects a charging path of the capacitor when charging the capacitor;
• a discharging path selection unit that selects a discharging path comprising the connection member and the capacitor when discharging the capacitor, and a determination unit configured to determine whether an abnormality has occurred in the battery pack, based on a voltage of the capacitor after discharging the capacitor.