What are the causes of leakage in lead-acid batteries?

　　01 The Principle of Electrolytes
　　Battery packs are generally divided into maintenance‑free conventional lead‑acid batteries and maintenance‑free high‑power lead‑acid batteries. “Maintenance‑free” means that no additional electrolyte needs to be added during subsequent maintenance.
　　During the production process, lead-acid batteries typically employ a low‑liquid technology. The ultrafine glass fiber separator channels inside the battery transport the O₂ generated at the positive electrode to the negative electrode for recombination and absorption. If the internal electrolyte level is too high, the relative pressure will increase significantly, potentially obstructing the recombination channels and thereby increasing the gas pressure within the battery. This can lead to leakage at any poorly sealed areas of the battery.
　　丨02 Leakage from the safety valve of the storage battery
　　One reason is that the rubber gasket around the safety valve has aged after many years of use, which compromises the battery’s sealing performance, leading to a decrease in the opening pressure. As a result, the safety valve remains open for an extended period, allowing gas to escape through the valve—and the gas will pre‑condense around the safety valve, turning into acidic liquid.
　　Another issue is that if too much acid is added to the battery, the battery will be in a highly liquid state, which obstructs the internal pathways for oxygen gas transport. As a result, the gases produced cannot be recombined at the negative electrode. When the accumulated gas pressure becomes too high, the battery’s safety valve will open frequently, and once the gas condenses into liquid, it leads to leakage.
　　丨03 Terminal Post
　　Electrode terminal leakage is a relatively common issue in data centers. After just one year of operation, individual electrode terminals may begin to leak; by the fifth year of operation, electrode terminal leakage typically becomes quite severe. The root cause of battery leakage lies in the poor fit between the electrode terminal metal and the sealing compound on the battery cover. In the acidic environment, the electrode terminals are corroded by oxygen, and under the influence of internal gas pressure, the electrolyte seeps along the corroded pathways to the terminal surface, resulting in leakage.
　　
　　丨04 The battery compartment cover is not securely sealed.
　　There are two main methods for sealing battery tray covers on the market: epoxy resin sealing and heat sealing.
　　The first type of epoxy resin sealant is primarily characterized by stringent sealing requirements. The epoxy adhesive formulation and curing conditions must be carefully controlled; otherwise, the bond between the shell and the sealant may be inadequate, creating leakage paths and resulting in battery leakage.
　　In the end, you still need to choose a battery brand that guarantees quality—such as Panasonic lead-acid batteries, Leoch lead-acid batteries, Kehua Jingwei batteries, and other major brands with reliable after-sales service. Their mature production processes and years of positive customer feedback will provide you with excellent assurance.
　　In addition, regular maintenance and inspection of the battery can extend its service life; promptly replace any batteries that show signs of leakage to ensure safe and reliable operation.