Abstract: In a clamshell housing, such as is used for portable devices, engaging elements other than screws or hooks are employed to prevent the two halves of a clamshell housing from having significant slippage between them along the interface at which they meet when the clamshell is subjected to bending and/or torsional moments. Such engaging elements may include slip preventing elements at the clamshell halves interface, e.g., various forms of interlocking teeth, elements that increase friction, or the like, which are added to, or molded into, each half of the housing. By restricting relative motion along the plane of the interface, the propensity to separate along the direction perpendicular to the interface plane is reduced. This is achieved because the restriction of the relative motion increases the bending and torsional rigidities.

Abstract: In a battery pack made up of battery cells encased within a housing made up of a stronger outer housing portion and a weaker inner housing portion, the battery cells are secured to the stronger outer housing portion. Advantageously, the relative motion between the battery cells and the stronger of the housing portions that results when prior art battery packs are dropped, and which causes catastrophic failure of the prior art battery packs, is prevented. The battery cells may be secured to the stronger outer housing portion, for example, by gluing the battery cells to the stronger housing portion, attaching the battery cells to the stronger housing portion by using double-sided sticky tape, molding features into the stronger housing portion that immobilize the battery cells adjacent to the stronger housing portion, or providing screw holes through the stronger housing portion so that screws may engage the battery cell or an appendage thereto.