BATTERY SYSTEM

A battery system includes a first battery cell including a first electrode terminal and a second electrode terminal, a connector configured to be electrically connected to the first electrode terminal, and a first circuit board detachably provided above the connector and configured to monitor a battery characteristic of the first battery cell. The connector includes a base including a terminal hole configured to be connected to the first electrode terminal and having a first plane, a connecting portion configured to be connected to the first circuit board and having a second plane non-planar with the first plane, and a stepped portion between the base and the connecting portion.