US Patent 10082542 Battery state detection apparatus and method for manufacturing same

A battery state detection device includes a casing (8) and a lid part (24). The casing (8) includes a board storage space (23) that stores a circuit board. The casing (8) includes an open mouth through which one side of the board storage space (23) is opened. The lid part (24) closes the open mouth of the casing (8). The lid part (24) is provided with a tapered surface (77). The casing (8) is provided with a contact portion (78) that can be in contact with the tapered surface (77). In a state where the tapered surface (77) and the contact portion (78) are in contact with each other, ultrasonic welding between the casing (8) and the lid part (24) is performed.