  The low-energy dynamics of any system admitting a continuum of static
configurations is approximated by slow motion in moduli (configuration) space.
Here, following Ferrell and Eardley, this moduli space approximation is
utilized to study collisions of two maximally charged Reissner--Nordstr{\"o}m
black holes of arbitrary masses, and to compute analytically the gravitational
radiation generated by their scattering or coalescence. The motion remains slow
even though the fields are strong, and the leading radiation is quadrupolar. A
simple expression for the gravitational waveform is derived and compared at
early and late times to expectations.
