The transport of charged species, including both polarons/bipolarons and charge-compensating ions, occurs when conjugated polymers switch between oxidized and reduced states. However, physics-based models of the charge transport processes have not yet been developed. Previously, we presented an electrochromic device that made the path for ion transport much longer than that for electrons, ensuring that ion transport was the rate-limiting step so that the constitutive equation for ion transport could be formulated. Ion concentration profiles and velocities could be tracked by color changes. In this paper, we present the correlation between ion transport and volume change, measured in this device using a mechanical profilometer to scan height profiles during electrochemical reduction. In addition, the effects of electrolyte concentration, electrolyte temperature, film thickness, and ion barrier stiffness on ion transport velocities are explored.