Evaporation of near-extremal Reissner-Nordstrom black holes
  The formation of near-extremal Reissner-Nordstrom black holes in the S-wave approximation can be described, near the event horizon, by an effective solvable model. The corresponding one-loop quantum theory remains solvable and allows to follow analytically the evaporation process which is shown to require an infinite amount of time. 
Alessandro Fabbri, Diego J. Navarro and Jose Navarro-Salas