Patent ID: 8797042

Claim:
A ground fault detection circuit comprising: a first switch circuit that connects or disconnects a first path between a positive bus bar and a ground potential section, the positive bus bar being connected to a positive electrode of a plurality of secondary battery units connected in parallel through a field-effect transistor including a parasitic diode; a second switch circuit that connects or disconnects a second path between a negative bus bar and the ground potential section, the negative bus bar being connected to a negative electrode of the plurality of secondary battery units connected in parallel; and a ground fault detection unit configured to detect a ground fault of the positive bus bar or the negative bus bar based on an electric current flowing through the first path or the second path when both of the first switch circuit and the second switch circuit are in a disconnected state; wherein the ground fault detection unit detects the ground fault based on the electric current in a state in which only one of the first path and the second path is connected; and wherein the plurality of secondary battery units connected in parallel includes a plurality of secondary batteries connected in series, and the ground fault detection unit detects a ground fault between the plurality of secondary batteries based on an electric current flowing through the first path in a state in which the first path is connected and based on an electric current flowing through the second path in a state in which the second path is connected.