Transport properties (ionic conductivities (σ), salt diffusion coefficients (D s), and cationic transference numbers (t + 0)) as a function of salt concentration (C s) are reported and compared for several common binary salt/polymer systems being considered for use as electrolytes in rechargeable lithium batteries for electric vehicle and other applications. The three properties provide a complete description of transport in solid polymer electrolytes (SPEs) or “dry” systems in cells undergoing galvanostatic charge and discharge. The macroscopic approach used obviates the need to know the details of speciation in these non-ideal solutions and allows for a more sophisticated correlation of the characteristics of ion transport with polymer structure, salt type, and concentration than conductivity data alone.