Heat energy vs. electrical energy in a galvanic cell or in an electrochemical reaction
Operational electrochemical cells have $\Delta G\lt0$
And,
$$\Delta G=-nFE$$
$$\Delta G=\Delta H-T\,\Delta S$$
Knowing the entropy change, enthalpy change could be calculated
or
$$\Delta H=-nFE+nFT\frac{\mathrm d\Delta G}{\mathrm dT}\quad\text{at contant }p$$