Battery not charging all of the time. Have replaced alternator.

Alternator output at the battery terminals should be 14 - 14.5 volts with engine running... Where did the alternator come from?

i would ck, the battery cables good sounds like just a bad connetion, make sure the connetions to battery are clean, if that is not it u have something pulling to many amps, so look for a bad wiring rubbing something and ck,all connetions on car,