  Near extreme black holes can lose their charge and decay by the emission of
massive BPS charged particles. We calculate the greybody factors for low energy
charged and neutral scalar emission from four and five dimensional near
extremal Reissner-Nordstrom black holes. We use the corresponding emission
rates to obtain ratios of the rates of loss of excess energy by charged and
neutral emission, which are moduli independent, depending only on the integral
charges and the horizon potentials. We consider scattering experiments, finding
that evolution towards a state in which the integral charges are equal is
favoured, but neutral emission will dominate the decay back to extremality
except when one charge is much greater than the others. The implications of our
results for the agreement between black hole and D-brane emission rates and for
the information loss puzzle are then discussed.
