What are the main factors that cause damage to lead-acid batteries?

China is the largest lead-acid batteries supplier. Lead-acid batteries have a history of more than 200 years and are a widely used power source. It has the advantages of easy material availability, low price, large discharge capacity and high reliability. At present, the market share is very high, and it cannot be completely replaced in the future for a long time.


      The design life of lead-acid batteries is about 5 years, but in actual use, the capacity is gradually reduced in 6~12 months, and the actual service life is only about one year. After analyzing a large number of failed batteries, the failure conditions were as follows: vulcanization, water loss, unbalanced grouping, softening, short circuit, and open circuit. Among them, "vulcanization" (lead sulphate crystal) accounts for more than 90% of the failed battery, which causes the battery capacity to drop and becomes the main reason for the end of battery life.


      The charging and discharging process of lead-acid batteries is an electrochemical reaction process. When charging, lead sulfate forms lead oxide, and when discharged, lead oxide is reduced to lead sulfate. Lead sulfate is a substance that is easy to crystallize. If the battery is not fully charged, if it is not charged in time, if it is over-discharged in a long time, or if the concentration of sulfuric acid in the battery is too high and the battery is idle for too long, a small crystal will form. These small crystals then adsorb the surrounding lead sulfate, forming a large inert crystal like a snowball. When the lead sulfate is crystallized, it can not be reduced to lead oxide, but also precipitates on the electrode plate, causing the working surface of the plate to fall. This phenomenon is called "vulcanization", which is also known as aging.


      Lead sulfate crystal is an insulator, and its formation will have a great negative impact on the charge and discharge performance of the battery. The more crystals of lead sulfate formed on the negative plate, the greater the internal resistance of the battery, the worse the performance of the battery charge and discharge, and the shorter the service life of the battery.


      In addition, when the lead sulfate crystals are accumulated in a large amount, the lead particles are attracted to form lead branches, and the lead bridge between the positive and negative plates causes a short circuit of the battery. If there is a gap in the surface of the plate or in the sealed molded case, lead sulphate crystals will accumulate in these gaps and cause expansion force, which eventually causes the plate to break off or the outer casing to rupture, causing irreparable physical damage to the battery.


      In summary, it can be seen that the main mechanism leading to the damage of lead-acid batteries is the "vulcanization" which cannot be avoided by the battery itself. It can be said that "vulcanization" is the deadly killer of lead-acid batteries. If the "vulcanization" phenomenon of the battery plate can be effectively and timely suppressed, the actual service life of the battery can be greatly extended.

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