When the alternator is operating, the expected battery terminal voltage is around which range?

• A. 12.0-12.2
• B. 14.0-14.1
• C. 11.5-12.0
• D. 13.5-13.8

Answer: (B)

When the alternator is working, the charging system is designed to push the battery voltage up to about 14 volts so the battery can be charged while the engine runs. The regulator controls this voltage, keeping the battery terminal voltage around a steady level that supports charging and powers electrical loads. Seeing a range of 14.0–14.1 volts at the battery indicates the system is in the proper charging state. The other ranges reflect either a battery that’s not being charged (around 12.0–12.2 volts when the engine is off) or voltages that are too low or not steady enough to indicate effective charging. So 14.0–14.1 volts is the expected charging voltage.