An interface for a battery pack and an electrical combination. The interface may include a battery-receiving portion configured to receive a battery pack and including a cavity. The cavity is defined by a pair of sidewalls with rails defining a groove between the rails and a lower surface of the cavity. The rails are stepped or angled along a battery insertion axis and are configured to guide the sliding engagement of a battery pack within the battery-receiving portion.

An interface for a battery pack and an electrical combination. The interface may include a battery-receiving portion configured to receive a battery pack and including a cavity. The cavity is defined by a pair of sidewalls with rails defining a groove between the rails and a lower surface of the cavity. The rails are stepped or angled along a battery insertion axis and are configured to guide the sliding engagement of a battery pack within the battery-receiving portion.

An interface for a battery pack and an electrical combination. The interface may include a battery-receiving portion configured to receive a battery pack and including a cavity. The cavity is defined by a pair of sidewalls with rails defining a groove between the rails and a lower surface of the cavity. The rails are stepped or angled along a battery insertion axis and are configured to guide the sliding engagement of a battery pack within the battery-receiving portion.

An interface for a battery pack and an electrical combination. The interface may include a battery-receiving portion configured to receive a battery pack and including a cavity. The cavity is defined by a pair of sidewalls with rails defining a groove between the rails and a lower surface of the cavity. The rails are stepped or angled along a battery insertion axis and are configured to guide the sliding engagement of a battery pack within the battery-receiving portion.

A method for fabricating an electricity storage device includes: preparing a square case including a rectangular opening; preparing a sealing plate to be attached to the opening along an edge of the opening; preparing assembly of attaching the sealing plate to the opening of the case; and performing main welding of laser welding the case and the sealing plate over an entire circumference of a periphery of the sealing plate. In the main welding, laser welding over the entire circumference of the sealing plate is performed in at least four steps.

An interface for a battery pack and an electrical combination. The interface may include a battery-receiving portion configured to receive a battery pack and including a cavity. The cavity is defined by a pair of sidewalls with rails defining a groove between the rails and a lower surface of the cavity. The rails are stepped or angled along a battery insertion axis and are configured to guide the sliding engagement of a battery pack within the battery-receiving portion.