Prevention and Judgment methods of Common Faults in Storage Batteries

1. Common Faults of Batteries and Their Prevention

1.1 Plate vulcanization

Plate sulfation is a phenomenon where white coarse grains are formed on the plates. These white coarse grains are known as lead sulfate, which is the most common phenomenon in storage batteries. The coarse-grained lead sulfate produced by plate sulfation has poor electrical conductivity, coarse grains, and large volume. It is difficult to be reduced to active substances under normal charging, which hinders the penetration and diffusion of the electrolyte. This significantly increases the internal resistance of the battery. When the engine starts and discharges, due to the large internal resistance, the voltage drops sharply and cannot continuously supply the starting current. So, what are the causes of sulfation of the plates? The fundamental cause of the recrystallization of PbSo4 is the long-term undercharging of the battery or the failure to charge it in time after discharge. During normal discharge, the lead sulfate grains formed on the plates are relatively small, and their electrical conductivity is relatively good. During charging, they can be reduced to lead dioxide and lead. However, if the battery is undercharged for a long time or not charged in time after discharge, lead sulfate will precipitate from the electrolyte and recrystallize into larger grains of PbSo 4, which will adhere to the surface of the plates. When the liquid level of the battery is too low, during the mechanical operation, due to the up and down fluctuation of the electrolyte, the part of the plates exposed above the liquid surface comes into contact with the air and is strongly oxidized, thus causing sulfation at the upper part of the plates. Excessive density of the electrolyte, impure electrolyte and drastic temperature changes are external factors that promote the formation of sulfidation.

Preventive measures: The main way to avoid sulfation is to keep the battery in a fully charged state at all times. Although the battery can be charged mechanically, it can only ensure basic charging. Therefore, it should be sent to the charging room for thorough charging every 1-2 months. For fully discharged batteries, they should be sent to the charging room for charging within 24 hours. For already sulfurized batteries, if the condition is not severe, the sulfurization charging method can be used for charging to eliminate the problem (sulfurization charging can be referred to relevant handbooks, so it will not be elaborated here).

1.2 Shedding of active substances

The shedding of active material mainly refers to the shedding of active material on the positive plate, which is the main cause of premature damage to the battery. The reasons for the shedding of active substances include: excessive charging current, overly long overcharging time, and low-temperature high-current discharge, etc. Overcharging will electrolyze water and produce a large amount of hydrogen and oxygen. When hydrogen and oxygen rush out from the pores of the negative and positive plates, it will cause the active material lead dioxide to fall off

Preventive measures: During the actual charging process, when the battery is basically fully charged, the charging current should be reduced by half.

1.3 Self-discharge

The phenomenon where a battery loses its charge on its own when it is unloaded is called self-discharge, or simply self-discharge. Self-discharge of storage batteries is inevitable. For fully charged storage batteries, if the capacity does not decrease by more than 2% per day and night within 30 days, it is considered normal discharge. The main reasons for the self-discharge of storage batteries are usage factors, such as excessive impurities in the electrolyte, high density of the electrolyte, and unclean battery surface.

Preventive measures: To avoid self-discharge, measures :1) When preparing the electrolyte, use sulfuric acid specifically designed for storage batteries and distilled water as stipulated in the international standard GB4564-84. 2) The vessels used for preparing the electrolyte must be made of acid-resistant materials, and the prepared electrolyte should be properly stored. 3) The plug of the battery's liquid filling hole should be tightly closed to prevent impurities from being mixed in. The dirt such as acid sludge on its surface should be wiped dry with clean water and kept clean and dry. For batteries with severe self-discharge, the electrolyte should be drained, the plate group removed, the separator pulled out, and then rinsed clean with distilled water. After reassembly, they can be used.

2. Common fault diagnosis methods for storage batteries

How can we make a judgment when the battery has the above-mentioned faults? One can determine whether the battery has any faults by observing it during charging.

2.1 Charging phenomenon of severely sulfated batteries

When charged at the normal charging current, the voltage will reach over 16.8V at the beginning of charging and a large number of bubbles will emerge. During the charging process, the temperature of the electrolyte rises rapidly, the temperature is high, and the density remains basically unchanged.

2.2 Battery charging phenomenon with severe shedding of active substances

During the charging process, there is a large amount of sediment in the electrolyte, the electrolyte becomes turbid and turns brown. The phenomenon of charging being completed occurs earlier, and the output capacity of the battery decreases.

2.3 Charging phenomenon of severely short-circuited batteries

During the charging process, the density of the electrolyte in the battery remains basically unchanged and no bubbles are produced, just like a stagnant pool. This is because the active substances do not participate in the electrochemical reaction.

In practical work, several faults may occur simultaneously in storage batteries, and the phenomena exhibited during charging are also rather complex. We must observe carefully and analyze meticulously to draw the correct conclusion.