Abstract: A drain valve includes a sealing member and an expansion member, where the sealing member is configured to be disposed on an outer side of a drain outlet of a battery box, the expansion member is disposed on a side of the sealing member facing the drain outlet, and the expansion member is configured to expand after absorbing water to extrude an edge of the sealing member to move in a direction leaving an inner side of the drain outlet.

Abstract: An automatic drain valve includes a valve body and a water-soluble assembly. The valve body includes an enclosed chamber and first and second openings communicating with the enclosed chamber separately, and the valve body passes through and closes a drain outlet. The first opening is located on an inner side of the drain outlet, and the second opening is exposed from the drain outlet. The water-soluble assembly is disposed in the enclosed chamber, the water-soluble assembly closes the second opening, and the water-soluble assembly opens the second opening after a water-soluble member in the water-soluble assembly is dissolved in water. The valve body passes through the drain outlet and closes the drain outlet, the first opening, enclosed chamber, and second opening of the valve body fit together to form a channel communicating the inside and outside of a box, and the water-soluble assembly is disposed in and blocks the channel.

Abstract: A drain valve includes a sealing member and an expansion member, where the sealing member is configured to be disposed on an outer side of a drain outlet of a battery box, the expansion member is disposed on a side of the sealing member facing the drain outlet, and the expansion member is configured to expand after absorbing water to extrude an edge of the sealing member to move in a direction leaving an inner side of the drain outlet.