12V

12V, or twelve volts, is a nominal direct current (DC) voltage used as a standard reference in many electrical systems. Because voltages vary with state of charge and chemistry, 12V is treated as a nominal value rather than a precise constant.

In automotive practice, a 12V electrical system is powered by a lead‑acid battery and an alternator. A fully charged 12V lead‑acid battery typically reads about 12.6–12.8 V with the engine off; during charging, system voltage is commonly around 13.8–14.4 V.

Beyond vehicles, 12V DC is widely used for portable and off‑grid applications, including solar power arrays, recreational vehicles, telecommunications equipment, and consumer electronics that accept 12V adapters or car power plugs.

12V remains a common standard in many regions, but it is not universal. Voltages may range, typically from about 11V when deeply discharged to around 14V during charging, depending on the chemistries and charging regulators. Higher‑voltage systems, such as 48V architectures, exist for some applications.

Safety and compatibility considerations include proper fusing, correct polarity, appropriate connectors, and awareness that several “12V” devices require a specific tolerance or battery chemistry.

Overall, 12V serves as a versatile, low‑voltage distribution standard for automotive, industrial, and consumer electronics.