Previous studies have shown that the electrical activation of a given implanted Al concentration in 4H-SiC increases with the increasing of the post implantation annealing temperature up to 1950–2100 C and different annealing times in the range 0.5–5 min. This study shows that, at 1950 C, the electrical activation of Al implanted in 4H-SiC increases with the increase of the annealing time up to attain saturation for annealing times longer than 22 min. Samples were obtained from the same Al implanted HPSI 4H-SiC wafer with an implanted Al concentration lower than the Al solubility limit in 4H-SiC at the annealing temperature of 1950 C. The annealing time was varied in the range 5–40 min.