In order to utilize the low-grade thermal energy efficiently, a more realistic model of thermally regenerative electrochemical cycles system with continuous power output is proposed in which the heat transfer irreversibility, external heat leakage and non-ideal regeneration losses are taken into account. Besides, the symmetry of cells, which is necessary for a practical thermally regenerative electrochemical cycles system operated at steady state, is considered. Analytic expressions for the efficiency and power output of the system are derived. The design and operation criteria of the system for achieving continuous power output are obtained. The general performance characteristics and the optimally operating regions of several parameters are reported. The influences of the external heat leakage on the system performance and the upper and lower bounds of efficiency at maximum power output at different situations are evaluated and discussed.