The technique for evaluating the material balance during transitions was presented in Part 1 of this series. In the present paper we investigate the energy balance in order to det. the consistency of the data. The same statistical test as used for the material balance can be applied to evaluate the error and, potentially, to reject the data consistency. Energy efficiency is calcd. using cumulative quantities, and our results show that the efficiency based on the enthalpy and on the free energy remained const., even for a changing metab. The results reported complete the data on themodynamic efficiency at steady state under various growth conditions. [on SciFinder (R)]