The phase diagrams and the spinodal lines of different types of charged hard sphere fluid mixtures (CHSM) are determined through the use of the mean spherical approximation (MSA). The attention in the paper is particularly addressed to the low density regime of these systems, where the physical parameters are chosen in such a way so to mimic polyelectrolyte solutions with an added salt, or dilute electrolyte solution mixtures of simple salts. The phase diagrams at densities corresponding to the molten salt regime, obtained in a previous paper, are also reported, in order to get a complete picture of the phase stability behavior of CHSM. In all cases investigated the MSA predicts the existence of a closed solubility loop in the low density domain of the phase diagram. The location and the extension of this feature turns out to be crucially affected by the pressure, by the diameter ratios of the ionic components, and by the asymmetry of the ionic charges. A comparison of the MSA predictions in the low density regime with more refined theoretical approaches, or with computer simulation data, has not been possible for reasons which are explained in the text. However, the theory is expected to work at the same level of accuracy as in other physical contexts, where its predictions for the phase stability conditions of various systems have been found to be qualitatively reliable; moreover, for the case in which the model mimics a polyelectrolyte solution with an added salt, the form of the theoretical spinodal closely resembles the cloud points curve of an ionic micellar solution experimentally investigated by other authors.