Battery enclosures include a pre-stressed bottom sheet having a convex surface, at least one vibration isolator disposed along at least a portion of a perimeter of the bottom sheet, a sidewall in contact with the at least one vibration isolator so as to be isolated from the bottom sheet, and at least one strap attached to the bottom sheet, the at least one strap being configured to hold a bottom surface of an outer casing of a battery against the convex surface of the bottom sheet such that internal battery cells are supported by a substantially planar surface.