A typical lead-acid battery used in automotive and other applications has a nominal voltage rating of 12 volts. This voltage is achieved by connecting six individual cells in series, with each cell producing around 2.1 volts. The nominal voltage of 12 volts is a standard for many vehicles and devices that rely on lead-acid batteries for power. It's important to note that the actual voltage of a lead-acid battery can vary depending on its state of charge and other factors, but 12 volts is the common reference point.