Zn+El/Li2SO4:Li2CO3 (60:40)/V2O5:P2O5 (60:40)+El+GR cells have been fabricated using the simultaneous pressing method. The voltage versus temperature response of the cells after 0%, 25% and 50% depth of discharge at 300 degrees C was measured. The data were then used to determine the Gibb’s free energy, enthalpy and thermoneutral potential of the cell. For 0% and 25% discharge of the cells, the positive values of the thermoneutral potential indicates an exothermic chemical cell reaction, while for 50% discharge it is negative, indicating an endothermic chemical reaction. This confirms that the nature of the chemical reaction taking place inside the cell during the discharge process depends upon the discharge region, which is in accordance with earlier reports.