That voltage isn't abnormal in relatively warm weather (not the dead of winter). It should move up to 14.2-14.5 when it is below freezing outside and with a cold engine. See if the voltage returns to the same value when you add or remove heavy loads like high beams and rear defogger. If so then there is probably nothing wrong. If you have an accurate meter measure at both the alternator positive post and the battery. If much different (more than 0.1V) then you would suspect the battery cables unless the battery is severely discharged.