1993 Bmw 318i New Alternat Two Days Old Draining Battery Exchanged Drove Car

I have new alternat two days old it was draining my old battery so I exchanged it with a new battery drove my car about 5 miles and as soon as i came into the driveway my car died out I checked the battery it was drained, alternator wasnt charging what can be wrong can the new alternator be bad what can be the prolbem has the recommended drive belt and pulley do i have a short something is drawing up to much power and the alternator isnt charging battery how do I know if the alternator is working properly