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In the field of modern industrial logistics, forklifts, as indispensable handling equipment, are widely used in various links such as warehousing, transportation, and loading and unloading. As the power source of electric forklifts, the performance of lead-acid batteries directly affects the working efficiency, service life of forklifts and the operating costs of enterprises. In the maintenance and care of lead-acid batteries, equalization charging is a crucial yet often overlooked task. A thorough understanding of the significance of equalization charging and strict compliance with operation norms are of great importance for ensuring the stable operation of forklift lead-acid battery packs and extending their service life.

1. Working Principle and Characteristics of Forklift Lead-Acid Battery Packs

Lead-acid batteries are a typical type of chemical power source, and their working principle is based on REDOX reactions. During the discharge process, the active substances on the positive and negative electrodes inside the battery undergo chemical reactions with the electrolyte, converting chemical energy into electrical energy to provide power for the forklift's motor, control system, etc. Lead dioxide at the positive electrode and lead at the negative electrode undergo reduction and oxidation reactions respectively under the action of sulfuric acid solution, generating lead sulfate and simultaneously releasing electrons to form an electric current. During the charging process, an external power source applies a reverse current to the battery, causing the above reaction to proceed in reverse. Lead sulfate is reconverted into lead dioxide and lead, allowing the battery to regain its electrical energy reserve.

Lead-acid battery packs are usually composed of multiple individual cells connected in series to meet the working voltage requirements of forklifts. However, due to the influence of factors such as manufacturing processes, material properties, and usage environments, there are certain differences in parameters such as capacity, internal resistance, and self-discharge rate of each individual battery. These minor differences will gradually accumulate over long-term use, leading to an imbalance in the performance of each individual battery in the battery pack and subsequently affecting the performance and lifespan of the entire battery pack.

2. The Importance of Equalization Charging

(1) Enhance the overall performance of the battery pack

During the operation of lead-acid battery packs, the charge acceptance capacity and discharge depth of each individual battery will vary due to performance differences. After long-term use, some individual batteries may experience overcharging or undercharging. Overcharged batteries will accelerate the aging of the plates and the consumption of the electrolyte, reducing the service life of the battery. Undercharged batteries cannot fully utilize their capacity, resulting in a decrease in the output power of the entire battery pack. Equalization charging, through a special charging procedure for the battery pack, can make the voltage and capacity of each individual battery tend to be consistent, thereby improving the overall performance of the battery pack, ensuring that the forklift can stably output power during operation, and reducing the occurrence of faults caused by unstable battery performance.

(2) Extend the service life of the battery pack

During the charging and discharging process of an unbalanced battery pack, each individual cell is subjected to different pressures. Cells with poorer performance will prematurely experience problems such as capacity attenuation and plate sulfation. Once a single battery malfunctions, it will further affect the normal operation of other single batteries, creating a vicious cycle and eventually leading to the premature scrapping of the entire battery pack. Equalization charging can effectively prevent this situation from occurring. By regularly performing equalization charging on the battery pack, the performance of each individual battery can be kept relatively consistent, reducing the performance differences among individual batteries, thereby extending the service life of the entire battery pack and lowering the equipment replacement costs for enterprises.

(3) Reduce operating costs

Frequent replacement of lead-acid battery packs not only increases the equipment procurement costs of enterprises, but also affects the production progress due to equipment downtime, causing indirect economic losses. By doing a good job in equalization charging and extending the service life of the battery pack, the operating costs of the forklift power system for enterprises can be significantly reduced. In addition, a well-performing and balanced battery pack can enhance the working efficiency of forklifts, reduce downtime caused by battery failures, further save operating costs for enterprises, and improve economic benefits.

(4) Ensure work safety

Battery packs with unbalanced performance are prone to safety hazards such as local overheating and electrolyte leakage during charging and discharging. Especially under overcharging conditions, a large amount of gas will be generated inside the battery. If it cannot be discharged in time, it may cause the battery casing to expand or even explode, endangering the safety of the operator and the surrounding equipment. Equalization charging enables battery packs to operate in a safe state, reduces the probability of safety accidents, and provides a strong guarantee for the safe production of enterprises.

3. Operating Specifications for Equalization Charging

(1) Preparations before charging

Check the appearance of the battery: Before performing equalization charging, carefully inspect the appearance of the lead-acid battery pack to see if there is any damage, deformation, leakage or other conditions on the battery casing. If any damage to the battery casing is found, its use should be stopped immediately and it should be repaired or replaced to prevent electrolyte leakage from causing equipment corrosion and personal injury.

Measure the density and liquid level of the electrolyte: Use a hydrometer to measure the density of the electrolyte in each individual battery. Under normal circumstances, the density of the electrolyte should comply with the standard value specified by the battery manufacturer. At the same time, check whether the electrolyte level is within the specified scale range. If the level is too low, distilled water or special lead-acid battery replenishment liquid should be added. However, it is strictly forbidden to add sulfuric acid solution to avoid affecting the concentration of the electrolyte and the performance of the battery.

Clean the battery surface: Wipe the battery surface with a clean damp cloth to remove dust, dirt and electrolyte residue, keep the battery surface clean and dry, prevent leakage on the battery surface, which may affect the charging effect and battery life.

(2) Operation process of equalization charging

Connect the charging equipment: Correctly connect the dedicated charger that meets the battery pack specifications to the battery pack, ensuring that the positive and negative terminals are accurately connected. During the connection process, the negative terminal of the battery pack should be connected first, and then the positive terminal. When disconnecting, the sequence is reversed to prevent the generation of electric sparks and the occurrence of safety accidents.

Set charging parameters: According to the user manual provided by the battery manufacturer, set parameters such as the charging voltage, current and charging time of the charger. The voltage of equalization charging is usually slightly higher than that of ordinary charging, and the charging current should not be too large to avoid damaging the battery.

Start charging: After setting the charging parameters, start the charger to begin equalization charging. During the charging process, it is necessary to closely observe the working status of the charger and the temperature and voltage changes of the battery pack. If the battery pack temperature is found to be too high or the charging current is abnormal, charging should be stopped immediately, the cause should be checked and dealt with.

Monitor the charging process: Measure the voltage and temperature of each individual battery at regular intervals and keep records. When the voltage of most individual cells reaches 2.6-2.7V and no longer rises within 2-3 hours, and the electrolyte begins to bubble vigorously, it indicates that the equalization charging is nearly complete.

End charging: When the termination conditions for equalization charging are reached, first turn off the power of the charger, and then disconnect the charger from the battery pack in the correct sequence. After the charging is completed, let the battery stand for 1 to 2 hours to allow the chemical reactions inside the battery to fully stabilize before proceeding to the next step.

(3) Maintenance work after charging

Measure the electrolyte density and liquid level again: After charging is completed, measure the electrolyte density and liquid level of each individual battery again. If the density of the electrolyte does not meet the standard value, it can be adjusted by adding distilled water or a sulfuric acid solution with a higher density. However, the adjustment process should be carried out slowly to avoid rapid changes in the density of the electrolyte affecting the battery.

Check the battery connection parts: Inspect whether the connection terminals between each individual battery in the battery pack are firm and whether there is any loosening, oxidation or other conditions. If loose connection terminals are found, they should be tightened with appropriate tools. If there is an oxide layer on the surface of the terminal, it can be sanded clean with sandpaper and an appropriate amount of Vaseline or special conductive paste can be applied to prevent oxidation of the terminal and ensure a good connection.

Record charging information: Record in detail the time of this equalization charge, charging parameters, status changes of the battery pack, etc., and establish a battery maintenance file. By analyzing the charging records, the performance changes of the battery pack can be understood in a timely manner, providing a basis for subsequent maintenance and care.

4. Frequency and Precautions of Equalization Charging

(1) The frequency of equalization charging

The frequency of equalization charging should be determined based on factors such as the usage frequency of the battery pack, the working environment, and the degree of battery aging. Generally speaking, for frequently used lead-acid battery packs of forklifts, it is recommended to perform a equalization charge every 10 to 15 regular charges. If the battery pack operates in a poor environment, such as excessively high or low temperatures, or high humidity, the frequency of equalization charging should be appropriately increased. For battery packs that have been in use for a long time, due to the rapid decline in battery performance, the frequency of equalization charging also needs to be increased.

(2) Precautions

It is strictly prohibited to charge in flammable and explosive environments: During the charging process of lead-acid batteries, flammable gases such as hydrogen are produced. Therefore, the charging site should maintain good ventilation. Charging in an environment with open flames, sparks or flammable and explosive gases is strictly prohibited to avoid explosion accidents.

Avoid overcharging and overdischarging: Although equalization charging is aimed at correcting the unbalanced state of the battery pack, it is also necessary to avoid overcharging. Overcharging will accelerate the aging of battery plates and the consumption of electrolyte, shortening the battery life. At the same time, during the use of forklifts, it is also necessary to avoid excessive discharge of the battery pack. When the battery power remains at 20% to 30%, it should be charged in time to prevent damage to the battery due to excessive discharge.

Use dedicated charging equipment: To ensure the effectiveness of equalization charging and the safety of the battery, a dedicated charger that matches the specifications of the battery pack must be used. The charging parameters of battery packs from different manufacturers and of different models may vary. Using non-dedicated chargers may lead to improper charging and damage the battery pack.

Operator training: Personnel conducting equalization charging operations should undergo professional training, be familiar with the working principle, performance characteristics, operation norms and safety precautions of lead-acid batteries. Untrained personnel are not allowed to perform equalization charging operations without authorization to avoid safety accidents and battery damage caused by improper operation.

In conclusion, the equalization charging of forklift lead-acid battery packs is of undeniable significance for enhancing the overall performance of the battery packs, extending their service life, reducing operating costs, and ensuring operational safety. Enterprises and operators should fully recognize the significance of equalization charging, strictly follow the operation norms to carry out equalization charging operations, and do a good job in maintenance before and after charging. They should reasonably determine the frequency of equalization charging and pay attention to all safety matters during the charging process. Only in this way can the lead-acid battery pack of the forklift always maintain a good performance state, providing reliable power support for the production and operation of the enterprise.