The charging system of the car

The charging system of the car
Generally, there is only one battery on the car, which belongs to the 12 volt power system; Some high-grade cars will be installed in parallel with the main and secondary two batteries, the supply voltage is still 12 volts; On the diesel engine, due to the large starting torque, two batteries are usually installed in series to form a 24 volt power supply system. So why is the battery voltage always 12 volts? This starts with the principle of generating electricity from the battery.

When the battery is at rest, at the positive plate, the lead dioxide and sulfuric acid react to generate positively charged lead ions to sink and float on the positive plate, so that the positive plate has a positive potential of 2V; At the negative plate, the pure lead is ionized into lead ions and electrons, and two electrons remain on the negative plate, so that the negative plate has a negative potential of about -0.1V; This creates a potential difference of about 2.1V between the positive and negative electrodes, which is how lead-acid batteries are able to build up their electromotive force. Such a battery composed of a pair of positive and negative plates is called a single cell battery. Generally, there are six pairs of single cell batteries in the battery. They are installed in series together to form a battery with a voltage of 12.6 volts, and the external nominal 12 volts. But in fact, if the battery voltage is measured at a static state of 12 volts, it will have little power left, generally fully charged battery voltage is between 12.6 and 12.8 volts.