how many volts should a car battery have

A healthy standard car battery is a 12‑volt battery, but the exact number depends on whether the engine is off or running.

Quick Scoop

• Engine off , after sitting for a while: about 12.6–12.8 volts = fully charged for a typical 12 V lead‑acid battery.

• Around 12.4–12.5 volts = roughly 75–90% charged, still OK but not perfect.

• Around 12.2 volts or lower at rest = getting weak and may struggle in cold weather.

• Below 12.0 volts at rest = effectively discharged; you’re in the “needs charge or replacement” zone.

When the engine is running , the alternator charges the battery, so voltage should be higher:

• Normal charging range while running: about 13.7–14.7 volts at the battery terminals.

• Much lower than ~13.5 V while running can mean poor charging.
• Consistently over ~15 V can mean overcharging, which can damage the battery over time.

Simple example

If you hook up a multimeter to a parked car that’s been off for an hour and read 12.7 V , that’s a healthy, fully charged 12 V car battery. If you then start the engine and the reading jumps to 14.2 V , the alternator is charging it properly.