As we all know, VRLA battery is a valve-regulated lead-acid batterie. It originated in the 1970s and by 1975 had already formed a considerable production scale in some developed countries, leading to industrialization and large-scale market deployment.
Although this type of battery is also a lead-acid battery, compared with the original lead-acid battery, it has many advantages and is highly favored by users, especially those who need to install batteries with equipment, such as UPS, telecommunications equipment, mobile communication equipment, computers, motorcycles, etc. This is because VRLA batteries are fully sealed and will not leak acid, and do not emit acid mist during charging and discharging, which can corrode equipment and pollute the environment, so structurally people call VRLA battery closed lead-acid battery. To distinguish them, the old-style lead-acid batteries are called open lead-acid batteries.
Since VRLA batteries are fully sealed and also have a valve for controlling the internal gas pressure of the battery, the full name of VRLA lead-acid batteries is "valve-regulated sealed lead-acid batteries".
VRLA battery, as an ideal replacement product for open lead-acid batteries, is increasingly widely accepted. As the number of VRLA battery users and VRLA battery supplier increases and the scope of use expands, as well as the deepening understanding and experience accumulated by production enterprises and users of VRLA batteries, it has been found that calling VRLA battery "maintenance-free batteries" is not accurate, nor is it practical. It can even be said that this name is wrong or misleading. In fact, any product will have its usage conditions and requirements. How do you know that the product you are using meets the usage conditions and requirements throughout its service life? Monitoring or measuring the technical parameters of the product regularly should be carried out, and the results or data of monitoring or measurement should be recorded, so that the results and data at different times can be compared and analyzed, and then corresponding judgments and dispositions can be made. If necessary, appropriate remedial measures can be taken for the battery; if there is a malfunction in the charging device for the battery or the set charging parameters are out of control, the battery often remains in a discharged state and cannot be charged. Any type of battery cannot withstand this situation.
Some people call baterie VRLA cathode absorption type lead-acid batteries. This name is not unreasonable. It is mainly derived from a more intuitive name based on the unique working principle of VRLA battery. When lead-acid batteries are charged, oxygen is generated at the positive electrode. Under closed conditions, with the extension of charging time, gas continues to increase and the internal pressure of the battery will increase accordingly.
Since VRLA batteries are poor liquid batteries, almost all of the electrolyte added to the battery is absorbed by the plate and the separator paper, and there is no excess liquid. Moreover, the separator paper used in baterie VRLA is made of ultrafine glass fiber material and has many small micropores. When there is a certain pressure inside the battery, the oxygen generated on the positive electrode will pass through the separator paper and run to the negative electrode under the action of the pressure. The product generated at the negative electrode during charging is sponge-like lead. This freshly generated sponge-like lead is highly active and will immediately be oxidized by the oxygen generated from the positive electrode, generating lead oxide. Lead oxide then reacts with oxygen to generate lead dioxide. Lead dioxide reacts with sulfuric acid to generate lead sulfate, which happens to be the product of negative electrode discharge. When charging, lead sulfate is transformed back into sponge-like lead, which absorbs oxygen generated from the positive electrode to generate lead oxide, thus continuously cycling like this. As a result, all the oxygen generated on the positive electrode is absorbed by the negative electrode, so it is called cathode absorption type lead-acid battery.