Lead-acid battery is a kind of battery whose electrodes are mainly made of lead and its oxides and whose electrolyte is sulfuric acid solution. In the discharged state, the main component of positive electrode is lead dioxide, and the main component of negative electrode is lead; in the charged state, the main component of both positive and negative electrodes is lead sulfate.
With the upgrade of battery manufacturing technology, the lead-acid battery is developed into lead-acid maintenance-free battery and colloidal maintenance-free battery. It mainly uses the positive electrode to produce oxygen which can be absorbed at the negative electrode to reach the oxygen cycle, which can prevent water reduction.
When the discharge is carried out, the concentration of sulfuric acid solution will keep decreasing, and when the density of the solution drops to 1.18g/ml, it should be stopped for charging. With the upgrade of battery manufacturing technology, lead-acid battery is developed into lead-acid maintenance-free battery and colloidal maintenance-free battery, and there is no need to add electrolyte or distilled water in the use of lead-acid battery. The main use of the positive pole to produce oxygen can be absorbed in the negative pole to reach the oxygen cycle, which can prevent the reduction of water. The capacity of the battery decreases and damage is mostly caused by overcharging. When charging will reach the top point, the charging current is only used to decompose the water in the electrolyte, at this time, the battery produces oxygen at the positive pole and hydrogen at the negative pole, and the gas will overflow from the battery, causing the electrolyte to decrease, which needs to be added from time to time.