What is a lead-acid battery?

Lead-acid battery (VRLA) is a storage battery whose electrodes are mainly made of lead and its oxides, and whose electrolyte is sulfuric acid solution. When the lead-acid battery is in the discharge state, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; when it is in the charging state, the main components of the positive and negative electrodes are both lead sulfate.
The nominal voltage of a single-cell lead-acid battery is 2.0V, which can be discharged to 1.5V and charged to 2.4V; in application, 6 single-cell lead-acid batteries are often connected in series to form a nominal 12V lead-acid battery, and there are also 24V, 36V, 48V, etc.