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Abstract

This article conducts an in-depth study on the bulging problem of lead-acid batteries in forklifts, systematically analyzing various causes of bulging, including abnormal charging processes, harsh usage environments, battery quality defects, and improper daily maintenance. At the same time, targeted and operational preventive measures have been proposed for various causes, aiming to help forklift user enterprises and relevant personnel effectively reduce the risk of battery bulging, extend the service life of batteries, ensure the safe and stable operation of forklifts, and provide references for the scientific management and maintenance of forklift lead-acid batteries.

1. Introduction

In the modern logistics industry, forklifts, as important handling equipment, are widely used in warehouses, ports, factories and other places. Lead-acid batteries, as the power source of electric forklifts, their performance and reliability directly affect the working efficiency and operational safety of the forklifts. However, in actual use, the problem of lead-acid battery bulging in forklifts occurs from time to time. Battery bulging not only leads to a decrease in battery capacity and a shortened service life, but in severe cases, it may also cause safety accidents such as battery leakage and explosion, bringing economic losses and safety hazards to enterprises. Therefore, it is of great practical significance to deeply analyze the reasons for the bulging of lead-acid batteries in forklifts and take effective preventive measures.

2. Analysis of the Causes of Bulging Lead-Acid Batteries in Forklifts

(1) Abnormal charging process

Overcharging

During the charging process of lead-acid batteries, when the battery voltage reaches a certain value, if high-current charging continues, overcharging will occur. When overcharged, intense chemical reactions occur inside the battery. The active substances on the positive plate will decompose at an accelerated rate, while a large amount of hydrogen will be produced on the negative plate and oxygen on the positive plate. These gases accumulate inside the battery. If they cannot be discharged in time, the internal pressure of the battery will increase, causing the battery casing to bulge. For instance, some enterprises, in order to enhance the operational efficiency of forklifts, stop charging the batteries before they are fully charged and then charge them again within a short period of time. Such frequent incomplete charging and overcharging behaviors greatly increase the risk of battery swelling.

Excessive charging current

Excessive charging current is one of the common causes of battery bulging. When the output current of the charger in use exceeds the rated charging current of the battery, the chemical reaction speed inside the battery will increase, and the heat and gas generated will also increase rapidly. Due to the limited speed of heat dissipation and exhaust inside the battery, excessive heat and gas cannot be dissipated and discharged in time, which will cause the internal temperature of the battery to rise and the pressure to increase, eventually leading to battery bulging. In addition, excessive charging current will also accelerate the aging and damage of battery plates, further affecting the performance and lifespan of the battery.

The charger does not match.

Lead-acid batteries of different specifications and models need to be charged with the corresponding chargers. If an unmatched charger is used, it may lead to problems such as excessively high or low charging voltage and unstable charging current. For example, charging a battery with a charger that has an excessively high output voltage will cause the battery to be subjected to an excessively high voltage during the charging process, thereby triggering overcharging. However, using a charger with an output voltage that is too low may lead to insufficient battery charging. Long-term insufficient charging can cause sulfation of the battery plates, which in turn can result in bulging. In addition, some low-quality chargers have low precision in voltage and current control, which can also easily cause damage to the battery and increase the possibility of bulging.

(2) The usage environment is harsh

High-temperature environment

Lead-acid batteries are relatively sensitive to the temperature of the operating environment. High-temperature conditions will accelerate the chemical reaction rate inside the battery, causing it to generate more heat. At high temperatures, the evaporation rate of the electrolyte inside the battery increases, the moisture content decreases, and the concentration of the electrolyte rises, thereby accelerating the corrosion and aging of the battery plates. At the same time, high temperatures will also accelerate the generation rate of gas inside the battery. The battery's heat dissipation and exhaust capabilities will be limited to a certain extent at high temperatures, which can easily cause the internal pressure of the battery to rise and lead to bulging. For instance, in summer when the outdoor temperature is relatively high, if forklifts are exposed to the sun for a long time or operate continuously in high-temperature workshops, the batteries are more likely to bulge.

Damp environment

A damp usage environment can cause corrosion to the casing and plates of lead-acid batteries. When the battery casing is eroded by a humid environment, its insulation performance will decline, which may cause an internal short circuit in the battery. An internal short circuit in the battery can cause excessive local current, generating a large amount of heat and subsequently leading to battery swelling. In addition, a humid environment can cause oxidation and sulfation reactions on the surface of battery plates, reducing their activity and affecting the battery's charging and discharging performance. Long-term exposure to a humid environment also increases the risk of battery swelling.

Vibration environment

Forklifts will inevitably generate vibrations during operation, especially when driving on uneven roads or carrying heavy objects, the vibrations are even more intense. Long-term vibration can cause the plates, separators and other components inside the battery to shift and loosen, resulting in poor contact between the plates and even short circuits. At the same time, vibration can also cause uneven distribution of the electrolyte inside the battery, affecting the charging and discharging performance of the battery. In addition, vibration may also cause damage to the battery casing, reducing its strength. When the internal pressure of the battery slightly increases, it is prone to bulging.

(3) Battery quality defects

Problems in the manufacturing process of the plates

The plate is one of the core components of lead-acid batteries, and its manufacturing process directly affects the performance and quality of the battery. If there are process defects in the manufacturing of the plates, such as uneven plate thickness and unstable coating of active substances, it will lead to uneven chemical reactions in different parts of the plates during the charging and discharging process of the battery. The areas with thinner plates or less active material coating have relatively weaker capacity and charging and discharging capabilities, and are prone to overcharging or overdischarging, which accelerates the damage and aging of the plates and causes battery bulging. In addition, if impurities are mixed in during the manufacturing process of the plates, it will also affect the performance of the plates and increase the risk of battery bulging.

The quality of the shell material is poor

The main function of the battery casing is to protect the plates, electrolyte and other components inside the battery, and at the same time withstand the pressure generated inside the battery. If the quality of the shell material is poor, its strength and corrosion resistance will not meet the requirements. During the use of batteries, when the internal pressure rises, poor-quality casings are prone to deformation or cracking, leading to the occurrence of bulging. For instance, some battery casings made of inferior plastic materials will rapidly decline in strength under the influence of environmental factors such as high temperature and vibration, and will be unable to effectively withstand the internal pressure of the battery, thus causing bulging.

Poor sealing performance

Good sealing performance is an important condition for ensuring the normal operation of lead-acid batteries. If the battery has poor sealing performance, the gas produced during the charging process cannot be effectively discharged and will accumulate inside the battery, causing the internal pressure to rise. At the same time, poor sealing performance can also cause the electrolyte inside the battery to leak easily, resulting in a reduction of the electrolyte and affecting the battery's charging and discharging performance. In addition, impurities such as moisture and dust from the outside may also enter the battery interior, causing damage to the battery and subsequently leading to bulging problems.

(4) Improper daily maintenance

Poor management of the electrolyte

Electrolyte is an important medium for chemical reactions in lead-acid batteries, and its liquid level and density have a significant impact on battery performance. If the electrolyte level is too low, the plates will be exposed to the air, causing sulfation of the plates and reducing the battery capacity. Meanwhile, the temperature of the exposed parts of the plates will rise, accelerating the aging and damage of the plates and increasing the possibility of bulging. On the contrary, if the electrolyte level is too high, during the battery charging process, the electrolyte is prone to overflow. This not only corrodes the battery casing and other components of the forklift but also causes changes in the electrolyte composition, affecting the battery's performance. In addition, if the density of the electrolyte does not meet the requirements, it will also affect the charging and discharging efficiency and service life of the battery, and further cause bulging problems.

Failure to conduct regular inspections and maintenance

Many forklift user enterprises do not attach sufficient importance to the daily inspection and maintenance of lead-acid batteries and have not established a complete battery maintenance system. During the battery usage process, if parameters such as voltage, current, electrolyte level and density of the battery are not regularly detected, problems existing in the battery cannot be detected in time. For instance, when a battery shows slight sulfation of the plates or local short circuits, if it can be detected in time and corresponding repair measures are taken, the further deterioration of the problem can be avoided. However, if these minor problems are not detected and dealt with in time, they will gradually expand, eventually leading to battery swelling or even scrapping. In addition, if the battery is not cleaned regularly, the dust on the battery surface and the residual electrolyte will lead to a decline in the insulation performance of the battery casing, increase the risk of short circuits, and also easily cause bulging problems.

3. Preventive Measures for Lead-acid Battery Bulging in Forklifts

(1) Standardize charging operations

Control the charging time and current reasonably

Charge strictly in accordance with the charging parameters provided by the battery manufacturer to avoid overcharging and excessive charging current. After the battery is fully charged, charging should be stopped in time. Generally, when the battery voltage reaches about 125% to 130% of the rated voltage and the charging current drops to a certain value (usually 0.05C to 0.1C, where C is the rated capacity of the battery), it can be considered that the battery is fully charged. At the same time, based on the battery capacity and usage conditions, select an appropriate charging current. Generally, the charging current should not exceed 0.2C. For example, for a battery with a capacity of 200Ah, the charging current should be controlled within 40A. In addition, to prevent frequent incomplete charging and overcharging, intelligent charging devices can be adopted. These devices can automatically detect the charging status of the battery and stop charging automatically when the battery is fully charged, effectively avoiding the occurrence of overcharging.

Use the matching charger

When charging the lead-acid battery of a forklift, a charger that matches the battery's specifications and model must be used. When purchasing a charger, carefully check its parameters to ensure that its output voltage, current and other parameters are consistent with the requirements of the battery. At the same time, choose a charger brand with reliable quality and good reputation, and avoid using inferior chargers. In addition, regularly inspect and maintain the charger to ensure that its voltage and current control accuracy is normal. Any problems found should be repaired or replaced in a timely manner.

Adopt scientific charging methods

In addition to the conventional constant current charging and constant voltage charging methods, scientific charging methods such as segmented charging and pulse charging can also be adopted. Segmented charging divides the charging process into several stages, with different charging currents and voltages applied in each stage. This can enhance charging efficiency, reduce battery heat generation and gas production. Pulse charging is carried out by periodically applying pulse current. This charging method can effectively reduce the sulfation of battery plates, extend the battery's service life, and lower the risk of bulging.

(2) Improve the usage environment

Control the ambient temperature

Try to avoid forklifts working for long periods in high-temperature environments and being exposed to direct sunlight. During the hot summer, forklifts can be parked in a cool and well-ventilated area or equipped with sunshade facilities to lower the temperature of the battery. Meanwhile, in indoor working environments such as workshops, the ambient temperature can be regulated by installing air conditioners, ventilation equipment, etc., to keep the battery working environment temperature between 20℃ and 30℃. In addition, heat dissipation devices such as heat sinks and fans can be installed on the battery casing to enhance the battery's heat dissipation capacity, lower the internal temperature of the battery, and reduce the possibility of bulging.

Keep the environment dry

Ensure that the workplace and storage location of the forklift are dry and well-ventilated, and avoid the battery being in a damp environment. For workplaces that are constantly in a humid environment, dehumidification equipment can be used to reduce air humidity. At the same time, regularly inspect the battery to prevent the battery casing from getting damp and corroded. If moisture or corrosion is found on the battery casing, it should be cleaned and dried in a timely manner, and corresponding protective measures should be taken, such as applying anti-corrosion paint, etc. In addition, when handling and storing batteries, it is necessary to avoid contact with water or other liquids to prevent internal short circuits of the batteries.

Reduce the impact of vibration

When driving a forklift, try to choose a flat road surface and avoid driving for a long time on bumpy and rough roads. For situations where driving must be done on uneven roads, the driving speed should be reduced to minimize the impact of vibration on the battery. At the same time, regular inspections and maintenance should be carried out on the suspension system and shock absorption devices of the forklift to ensure their good performance and the ability to effectively absorb and buffer vibrations. In addition, when installing the battery, it is necessary to ensure that the battery is firmly fixed. Shock-absorbing pads can be added between the battery and the forklift installation bracket to further reduce the impact of vibration on the battery.

(3) Strictly control the quality of batteries

Choose high-quality battery products

When purchasing lead-acid batteries for forklifts, it is necessary to choose products produced by regular manufacturers and of reliable quality. When choosing a battery brand, pay attention to the brand's reputation and word-of-mouth, and give priority to brands with high market share and good user reviews. At the same time, carefully review the product manual and quality inspection report of the battery to understand the performance parameters, manufacturing process and quality assurance measures of the battery, etc. In addition, you can also consult other users or professionals to obtain usage experiences and evaluations of batteries from different brands, which can provide references for choosing high-quality batteries.

Strengthen the quality inspection of batteries

In the battery procurement process, quality inspection work should be strengthened. Conduct a strict visual inspection of newly purchased batteries to check if there are any defects such as damage, deformation or cracks in the battery casing, and to verify if the battery's sealing performance is good and if there is any leakage. At the same time, the internal structure of the battery should be inspected, such as checking the quality, thickness of the plates, and the coating of active substances, to ensure that the internal components of the battery meet the quality requirements. In addition, charge and discharge tests can also be conducted on the battery to detect its capacity, voltage, charge and discharge efficiency and other performance indicators, ensuring that the battery quality meets the usage requirements.

Establish a battery quality traceability system

To ensure the traceability of battery quality, enterprises should establish a complete battery quality traceability system. In the links of battery procurement, use and maintenance, detailed records should be made of information such as the battery manufacturer, production date, batch number, usage status and maintenance records. When battery quality problems occur, the cause of the problem can be quickly identified through the traceability system, and corresponding solutions can be taken in a timely manner. Meanwhile, through the analysis and summary of battery quality traceability information, it can also provide references for enterprises' future battery procurement and management, continuously improving battery quality and management level.

(4) Strengthen daily maintenance and management

Standardize the management of electrolyte

Regularly check the electrolyte level, usually once every 1 to 2 weeks, to ensure that the electrolyte level is between the upper and lower limit marks marked on the battery casing. If the electrolyte level is too low, distilled water or dedicated lead-acid battery replenishment liquid should be added in time. Avoid adding other liquids, such as tap water, as tap water contains impurities that can affect battery performance. After adding the electrolyte, it should be thoroughly stirred evenly to ensure that the density of the electrolyte meets the requirements. Under normal circumstances, the density of the electrolyte in lead-acid batteries should be around 1.28g/cm³ at 25℃. Different types and specifications of batteries may have different requirements for the density of the electrolyte. Specific adjustments should be made according to the requirements of the battery manufacturer. In addition, regularly test the density of the electrolyte and adjust the composition of the electrolyte in a timely manner based on the test results to ensure the normal operation of the battery.