TECH TIP #102 — CHARGING VOLTAGE AND AIR TEMPERATURE

Depending on the air temperature, charging voltage usually runs between 13.5 and 14.8 volts. The actual charging voltage that is designed into a voltage regulator depends on things like how far the alternator is from the battery and the air temperature around the battery as calculated by the PCM. Under normal conditions, an alternator should maintain around 14.2 volts at 70 degrees F.