What was the car doing before you had issues ?

What were the issues & what was tested to decide
an alternator was needed?

If your changing parts on a guess without testing for failure
then I can't help you

Is the new alternator actually the correct part for your car
& do you have the old one to take to the store to have it
tested ? Always keep your cores until you resolve vehicle issues

Sounds like the new alternator is different inside