Hmm... depends on who you ask. Weak Fi types will tell your charge is a convention, something used to describe two opposites. Strong Fi types will correlate charge to real-world, concrete phenomena, and almost always on basis of favored/unfavored.
Every type in the rational club has weak Fi, and most of the physicists are rationals so... what does that tell you? Now Gulenko and Bukalov did the Model B system, but where could one find information on it?