The transported entropy and the Thomson coefficient for charge conducting ions are needed to predict reversible heat affects in batteries. Transported entropies and Thomson coefficients have been calculated from Seebeck coefficients of the cell Fe(s, T1)Me beta" aluminaMe Fe(s, T2) for Na and K (Me). The result is S(Na+)* = 56 +/- 3 JK-1 mol-1 at 500K, with a Thomson coefficient tau(Na+) = 30 +/- 2JK-1 mol-1 in the temperature interval 333-773K. The transported entropy of Na+ did not change by freezing Na at 370. The results for K+ are identical to those of Na+, within the accuracy of the experiments. The Thomson coefficient derived from measurements at different values of T1 was consistent with the observed variation in emf with DELTAT for a given T1. The reversible heat changes at the electrodes have been calculated for sodium sulphur and potassium sulphur batteries. During discharge both batteries produce a net reversible heat, the production always being largest at the alkali metal anode. At the cathode, the heat effect becomes relatively small when the composition of Na and S is within the one phase region. A change in composition from the one phase to the two phase region is expected to lead to changes in local temperature gradients. The systems were described by the electric work method, a method which has practical advantages compared to other electrochemical methods.