[ijames]

Way back when, up through maybe the early '90s, alternator regulators were set to give 13.8 V. Battery chemistry has changed a little since then, and nowadays most alternators are set to give more like 14.2 V. Depending on when and if your alternator has been replaced or rebuilt, you could have either one. And then, depending on where you are checking the voltage, you will have the wiring losses as well. With every thing on the car powered up there will be 0.1-0.3 V drop just across the charging wire that runs from alternator to battery, and then another 0.2-0.5 V getting through the fusebox and out to a high draw accessory such as the radiator fan or headlights.