Battery is a kind of battery. Its function is to store limited electric energy and use it in a suitable place. Its working principle is to convert chemical energy into electrical energy. It uses a lead plate filled with sponge lead as the negative electrode, a lead plate filled with lead dioxide as the positive electrode, and 1.28% dilute sulfuric acid as the electrolyte.

During charging, electrical energy is converted into chemical energy, and during discharge, chemical energy is converted into electrical energy. When the battery is discharged, the metal lead is the negative electrode, which will undergo oxidation reaction and be oxidized to lead sulfate; Lead dioxide is the positive electrode, which undergoes a reduction reaction and is reduced to lead sulfate. When the battery is charged with direct current, lead and lead dioxide are generated at the two poles respectively. After removing the power supply, it returns to the state before discharge and forms a chemical battery. Lead-acid battery is a battery that can be repeatedly charged and discharged, which is called secondary battery. Its voltage is 2V. Usually, three lead-acid batteries are connected in series. The voltage is 6V. The car uses six [2] lead-acid batteries in series to form a 12V battery pack. Distilled water should be added to lead-acid batteries after they are used for a period of time to keep the electrolyte containing 22 ~ 28% dilute sulfuric acid. During discharge, the electrode reaction is: PbO2 + 4H + SO42 - + 2E - = PbSO4 + 2H2O negative reaction: Pb + SO42 -- 2e - = PbSO4 total reaction: PbO2 + Pb + 2h2so4 = = = 2pbso4 + 2H2O (the right reaction is discharge and the left reaction is charge)