In mobility, waste heat originating from ultra-low-temperature sources (25–80 °C) represents a significant but largely untapped energy resource. With conventional heat recovery solutions (e.g., the Organic Rankine Cycle), this type of heat loss is either not or only poorly exploitable. Therefore, thermally regenerative electrochemical cycles offer a promising solution, as they can directly convert low-temperature thermal energy into electricity. This research investigated the dynamic behavior of a system using iron- and iodine-based redox pairs. In the model, the temporal variations of reactant concentrations were simulated over 24 h, along with the electromotive force, which ranged between 0.38 and 0.36 mV. Based on our results, the system’s electromotive force closely follows the concentration changes (theoretical value: 0.39 mV), which means that the regeneration process can be effectively controlled solely based on voltage. This enables the optimisation of pump operation using voltage as the input parameter for pump control, avoiding unnecessary pump cycling. The method may be particularly promising for dynamic vehicle applications, where concentration measurement is difficult to implement.