A car battery typically measures 12.6 volts when it is fully charged and the engine is off. This voltage is often referred to as the “resting voltage” of the battery. It represents the amount of electrical potential stored in the battery when it is not being used to power any devices or systems in the car.
When the engine is running, the battery voltage will usually rise to a higher level, typically between 13.5 and 14.5 volts. This increase in voltage is due to the alternator in the car, which is responsible for charging the battery and providing power to the electrical components of the vehicle.
I remember a time when my car battery was running low and I had to jump-start it. Before connecting the jumper cables, I checked the voltage of the battery using a multimeter. It showed around 11 volts, indicating that the battery was quite depleted. After jump-starting the car and letting the engine run for a while, I rechecked the battery voltage and it had risen to around 14 volts, indicating that the alternator was successfully charging the battery.
It’s important to note that the voltage of a car battery can vary depending on its state of charge, the temperature, and the condition of the battery itself. In extreme cold temperatures, for example, the battery voltage may be slightly lower. Additionally, an old or damaged battery may not reach the same voltage levels as a newer and healthier one.
To summarize, a fully charged car battery will typically measure 12.6 volts when the engine is off. When the engine is running, the battery voltage will rise to around 13.5 to 14.5 volts due to the charging action of the alternator.