flickering lights on 1998 Oldsmobile Regency

the other morning my car died while the engine was Idling,then the lights started flickeringand it died.I took my alternator and my battery and had them testedthey said alternator was good but battery was very low, so since it was a very old battery I got a new one put it in and car works the lights are flickering again and battery light that reads volts below it comes on? can someone please help me?

Asked by for the 1998 Oldsmobile Regency
It sounds like your alternator is not charging correctly. If the alternator is indeed not working and it tests ok the the fault may be with the electrical circuits that control the alternator.