Concave fuel cell knock out drain

A vehicle includes a high-voltage bus and an electric motor electrically coupled to the bus. The vehicle further includes a fuel cell system electrically coupled to the bus. The fuel cell system includes a fuel stack and a reservoir in fluid connection with the fuel stack. The reservoir has a concave, generally conically-shaped bottom wall extending upwardly into and forming an apex within a cavity of the reservoir. The reservoir further includes a valve receptacle extending from a sidewall of the reservoir into the cavity of the reservoir. The valve receptacle defines a drain aperture and an outlet orifice having a bottom edge disposed proximate the apex of the bottom wall. The fuel cell system further includes a drain tube in fluid communication with the drain aperture and a control valve disposed within the valve receptacle and adapted to control fluid communication between the outlet orifice and the drain aperture.