An exemplary battery assembly includes, among other things, an enclosure defining an interior, and a frame disposed within a wall of the enclosure. The frame includes at least one retention feature configured to hold a service panel in a position where the service panel covers an opening to the interior. An exemplary method includes, among other things, transitioning a service panel to an engaged position with at least one retention feature to secure the service panel in a position where the service panel covers an opening in an enclosure. The at least one retention feature is provided by a frame disposed within a wall of the enclosure.