14.6 is an ideal output for those systems
if its under 14 then there may be high resistance in the charging wire off the alternator large terminal that goes to the battery. If its like the mitsu/cats there are a couple of fuselinks that can corrode up and cause high resistance also.

And if/when you replace that alternator? get a NEW one, the remans dont work half the time. 3rd party aftermarket regulators in those remans are junk.