  The universal properties of charged particles are modified by the presence of
a long-range Coulomb interaction. We investigate the modification of Efimov
universality as a function of the Coulomb strength using the Gaussian expansion
method. The resonant short-range interaction is described by Gaussian
potentials to which a Coulomb potential is added. We calculate binding energies
and root mean square radii for the three- and four-body systems of charged
particles and present our results in a generalised Efimov plot. We find that
universal features can still be discerned for weak Coulomb interaction, but
break down for strong Coulomb interaction. The root-mean-square radius plateaus
at increasingly smaller values for strong Coulomb interaction and the
probablity distributions of the states become more concentrated inside the
Coulomb barrier. As an example, we apply our universal model to nuclei with an
alpha-cluster substructure. Our results point to strong non-universal
contributions in that sector.
