Manually controlled generator charging rate control was needed on very short drives to get battery charged from short drives. A rheostat is placed in field circuit of generator to dial in wanted charging rate to battery. A separate volt meter connected to ignition circuit showed battery voltage levels.
Three left coils are the generator field coils. AC Source is armature in generator. Instead of regulator (relay) turning field coil on or off we insert dial rheostat for manual control.
