An expression is investigated for inverse relaxation time for electroconductivity in the simple disordered metals within a framework of a kinetic equation method and a perturbation theory by the powers of a pseudopotential of electron-ion interaction. Numerical calculation of the third-order term by a pseudopotential for inverse relaxation time of 25 simple disordered metals is carried out. Three different model local pseudopotentials are used. Strong relation of the results of calculation between the choice of a model pseudopotential and concrete values of the pseudopotential parameters is found out for all metals. Selection criterions for the model pseudopotentials are formulated.