The S wire on the voltage regulator runs to the S terminal on the alternator, the alternator S terminal supplies about 6-11 volts when the engine is running to turn the voltage regulator on. If this wire is not hooked up or has no voltage the regulator will never be turned on to start the charging system. You need to check this out. Also there is a wiring and vacuum diagrams at the top of this forum, that has the color of the wires, and that should help. Since you have 2 wires connected to the ground terminal on the alternator, see if one of them is the S wire to the regulator, and if it is, then connect it to the S term on the alternator, start the car, and see if it is charging then. Also it is not recommended to remove either of the battery post cables when the engine is running, as a high voltage spike is possible, which can damage the diodes in the alternator. Post your results. Good luck.