  Spontaneous loss of charge by charged black holes by means of pair-creation
of charged Dirac particles is considered. We provide three examples of exact
calculations for the spontaneous discharge process for 4D charged black holes
by considering the process on three special non-rotating de Sitter black hole
backgrounds, which allow to bring back the problem to a Kaluza-Klein reduction.
Both the zeta-function approach and the transmission coefficient approach are
taken into account. A comparison between the two methods is also provided, as
well as a comparison with WKB results. In the case of non-zero temperature of
the geometric background, we also discuss thermal effects on the discharge
process.
