1. Meaning of maintenance-free battery

The main advantage of the valve-controlled lead-acid battery is that the oxygen generated on the positive plate during charging is reduced to water on the negative plate through the recombination reaction, and water does not need to be added during the specified floating life period when used, so it is also called maintenance-free lead-acid battery. It can be seen that maintenance-free is only compared with ordinary batteries, the addition of pure water or distilled water and the adjustment of the liquid level of the electrolyte are eliminated in operation, and all maintenance work is not eliminated.

2. People often say that the regular name of the maintenance-free battery is called the valve-controlled sealed lead-acid battery. A valve-controlled sealed lead-acid battery has a shell, a valve cover, and a wiring terminal. The sealing material around the terminal is red and black (or blue) respectively to indicate the positive and negative terminals. The 12V battery is divided into six independent cells isolated from each other, each cell has a positive plate group and a negative plate group connected by their own bus conductor. The plate of the lead-acid battery is like the structure of reinforced cement, which is formed by coating (or rolling) active substances on the sift-like skeleton of the alloy wire: the material on the positive plate is lead dioxide (PbOz), and the material on the negative plate is velvet lead (Pb). Each positive and negative plate is separated by a porous microfiber material (also filled with silica gel material), which adsorbed sulfuric acid (HzSO4) electrolyte, this fiber material (or silica gel material) is the liquid phase transport and gas phase transport channel in the electrochemical reaction process, it and the positive and negative plate group are closely assembled together. Form a 2V battery cell. Since the plate of the lead-acid battery inevitably produces hydrogen and oxygen when it is charged, when they are produced too much and too late to melt and form water, pressure will be formed in the cell. In order to ensure the normal and safe operation of the battery, each single cell has its own overflow valve, which allows the gas to escape automatically when the pressure is excessive. Compared with the rich liquid battery filled with electrolytic liquid in the battery tank, the valve-controlled sealed lead-acid battery contains only a small amount of electrolyte inside, which is a lean liquid battery. However, due to the design of the electrolyte has a certain redundancy, and under the protection of the overflow valve pressure, as long as the use is reasonable, the water loss caused by the gas escape is minimal, and the electrolyte of the valve-controlled battery is basically not supplemented during the life process, so the valve-controlled sealed lead-acid battery is also known as maintenance-free battery.