1991 Mercury Capri Battery light is on, Volt meter shows 11

Car had what seemed like a low battery, Tried to jump very slow crank, Replaced Starter, Battery car started right up but battery light was on and the volt meter showed 11.5 volts. Replaced Alternator same problem car starts and drives but battery light stays on and volt meter shows 11.5 volts and remains unchanged at any speed. Car has been driven approx 5 miles with no changes in symptoms