Charging system not chargeing

It's likely that the alternators you're getting are all bad. They are internally controlled and signaled by the engine's ECU. When charging is needed the ECU signals the alternator to start. Your alternators are not handling that signal consistently, or there's a problem in communicating with the ECU due to an incompatibility in the alternators themselves. Or due to the continued voltage loss, the car might have lost its memory and is unable to signal properly. I suggest you get better products like OEM to avoid this common condition. It might be easiest for you to have a mechanic do this repair as the car's memory or failed ECU could be the problem.