Portable devices have ushered in the use of parameterizable system-on-a-chip (SoC) architectures that provide flexibility and applicability while remaining cost-effective. In order to extend the lifetime of these devices, it is important to consider the interaction of the power source or battery with the SoC. This is because batteries have non-linearities that need to be incorporated into the design of the SoC. This book derives optimal congurations for battery powered systems and demonstrates that they are different from those designed for maximizing power or energy consumption. It proposes an efficient way of arriving at a conguration that meets the given performance criterion by exploring the large configuration space using a coarse to fine search method. The thesis also looks at the problem of finding the best configuration for a given time constraint when multiple applications have to be mapped onto a single SoC or when multiple applications have to be mapped onto multiple SoCs.