  We study how the entanglement entropy of the Hawking radiation derived using
island recipe for the Reissner-Nordstr\"om black hole behaves as the black hole
mass decreases. A general answer to the question essentially depends not only
on the character of decreasing of the mass but also on decreasing of the
charge. We assume the specific relationship between the charge and mass
$Q^2=GM^2[1-\left(\frac{M}{\mu}\right)^{2\nu} ]$, which we call the constraint
equation. We discuss whether it is possible to have a constraint so that the
entanglement entropy does not have an explosion at the end of evaporation, as
happens in the case of thermodynamic entropy and the entanglement entropy for
the Schwarzschild black hole. We show that for some special scaling parameters,
the entanglement entropy of radiation does not explode as long as the mass of
the evaporating black hole exceeds the Planck mass.

High Energy Physics - Theory