It was shown by experiments for SAFT batteries of stationary application and medium rate of discharge, that empirical equations Korovin-Skundin's, Peukert's generalized equation, probability integral, porous electrode equation allow to describe the dependence capacitance C(f), given by nickel-cadmium batteries, from discharge current with the accuracy sufficient for practical needs (5-6%) on all the range of discharge currents. Meanwhile the empirical equations of Peukert and Aguf can be used to calculate the capacitance given away only within the discharge currents, starting from the point of inflexion of experimental curve C(i) infinitely. Libenov equation, which can be used only within the range of discharge currents from the point of inflexion of experimental curve C(i) and up to the discharge currents, wherein С(i) ≈ 0.05Cn, is of even bigger specialty.