What are the failure scenarios of valve-regulated sealed lead-acid batteries?

There are several situations in which valve-regulated sealed lead-acid batteries fail: 1. Corrosion and deformation of the positive plate. There are currently three types of alloys used for processing positive electrodes: traditional lead-antimony alloys, with an antimony content of 4%-7% (mass fraction): low antimony or super antimony alloys, with an antimony content of more than 2% or less than 1% ( Mass fraction), lead calcium alloy (actually lead calcium antimony aluminum quaternary alloy), the mass of calcium is 0.06%-0.1% (mass fraction). The positive grid made of the above alloys will be oxidized into lead sulfate and lead dioxide during the battery charging process, losing the use of supporting active materials and causing the battery to fail, or lead sulfate corrosion has formed lead alloys to cause stress. The grid grows into shape. When this kind of deformation exceeds 4%, the whole will be destroyed, and the active material will fall off due to poor contact with the grid. Or short circuit at the bus bar. 2. The active material of the positive plate falls off and softens. In addition to the active material falling off due to the growth of the grid, as the charge and discharge are repeated, the lead dioxide particles will relax, soften, and fall off the grid. The manufacturing and assembly of the grid and the tightness of the charge and discharge A series of factors such as conditions will have a certain influence on the softening and shedding of the active material of the positive plate. 3. Irreversible sulfation. When the battery is over-discharged and stored in a discharged state for a long time, its negative electrode will form a kind of coarse sulfuric acid crystals that are difficult to accept charging. This phenomenon is called irreversible sulfation. Slightly irreversible sulfation is still available to restore it. In severe cases, the instructor electrode fails and cannot be charged. 4. Premature loss of capacity. When an antimony alloy or lead-calcium alloy grid is used, antimony accumulates heavily on the active material. As the charge-discharge cycle progresses, the antimony portion of the positive electrode grid is transferred to the surface of the negative electrode active material. Since most of the hydrogen ion current is decomposed by water, the battery cannot be charged normally. In the initial stage of the battery's use (about 20 cycles), the flux suddenly drops, causing the battery to fail. 5. Thermal failure. Regarding valve-regulated sealed lead-acid batteries, it is required that the charging voltage does not exceed the single-cell voltage (2.4V). But in actual use, the charging voltage may be too high. As a result, the charging current is too large, and the heat that appears will increase the temperature of the battery electrolyte and reduce the internal resistance of the battery. The decrease in internal resistance further increases the charging current and the battery temperature rises even higher. Such a vicious circle will eventually cause the battery to deform, crack and fail. Although thermal failure is not a failure mode that often occurs in VRLA batteries. But it's not uncommon. Pay attention to the phenomenon that the charging voltage is too high and the battery heats up during use. 6. Corrosion of the negative busbar. Under normal circumstances, there is no corrosion problem for the negative grid and busbars. However, when the valve-regulated sealed lead-acid battery establishes an oxygen cycle, the upper space of the battery is filled with oxygen, causing a small amount of electrolyte in the diaphragm to climb up the tabs to the slag and crevices in the busbar, and corrosion will follow these crevices The deepening causes the tabs and the bus bar to pull apart, and the negative grid fails. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the important uses of batteries?