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1. Introduction

In the modern logistics and warehousing industry, forklifts, as indispensable handling equipment, the performance of their power systems directly affects the production efficiency and operating costs of enterprises. Lead-acid batteries have become the mainstream choice for forklift power sources due to their mature technology, low cost, and adaptability to heavy-load operations. However, the service life and performance of lead-acid batteries are closely related to daily maintenance, inspection and replacement. Scientific and reasonable maintenance, precise detection and timely replacement can not only extend the service life of the battery, reduce operating costs, but also ensure the safe and stable operation of the forklift. This article will conduct an in-depth discussion on the maintenance, inspection and replacement of lead-acid batteries in forklifts, providing practical and instructive references for relevant practitioners.

2. Maintenance of Lead-Acid Batteries in Forklifts

(1) Daily cleaning and maintenance

During the use of lead-acid batteries, dust, dirt formed by the overflow of electrolyte and other impurities are prone to accumulate on their surfaces. These dirt not only affect the appearance of the battery, but may also cause surface leakage of the battery and reduce its performance. Therefore, daily cleaning is the basic work of maintenance. Operators should regularly wipe the battery surface with a clean damp cloth to remove dust and dirt, and be careful to avoid using tools that may scratch the battery casing. For stubborn stains, a diluted sodium bicarbonate solution can be used for cleaning. After cleaning, rinse with clean water and dry thoroughly to ensure the battery surface is dry and clean.

(2) Electrolyte Management

Liquid level check

During the charging and discharging process of lead-acid batteries, the water in the electrolyte will continuously evaporate, causing the liquid level to drop. It is crucial to regularly check the electrolyte level. Generally, it is recommended to do so at least once a week. When conducting the inspection, ensure that the forklift is in a horizontal position. Open the battery cover and observe whether the electrolyte level is between the plate protection plate or the liquid level scale line. If the liquid level is lower than the standard value, distilled water or special lead-acid battery replenishment liquid should be added in time. Do not add tap water, as the impurities in tap water may affect the performance of the electrolyte and even cause battery damage.

Density detection and adjustment

The density of the electrolyte has a significant impact on the performance and lifespan of the battery. An appropriate electrolyte density can ensure the charging and discharging efficiency of the battery and the normal progress of chemical reactions. The density of the electrolyte is usually detected by a hydrometer. The requirements for the density of the electrolyte vary slightly in different seasons and regions. If the density of the electrolyte is detected to be too high, distilled water should be added for dilution. If the density is too low, a special sulfuric acid solution needs to be added for adjustment. During the adjustment process, add slowly and stir thoroughly to ensure uniformity. At the same time, pay attention to safety precautions to avoid splashing the sulfuric acid solution and injuring people.

(3) Charging Management

The correct charging method

Forklift lead-acid batteries should be charged by appropriate methods. Common charging methods include constant current charging, constant voltage charging and staged charging. Staged charging is currently a relatively ideal charging method. It is generally divided into constant current charging stage, constant voltage charging stage and float charging stage. During the constant current charging stage, the battery is charged with a constant current to quickly replenish its power. When the battery voltage rises to a certain value, it enters the constant voltage charging stage, maintaining a constant charging voltage while the current gradually decreases to further charge the battery. Finally, it enters the float charging stage, where the battery is charged at a low voltage with a small current to maintain its full charge state and compensate for the self-discharge loss of the battery at the same time.

Avoid overcharging and undercharging

Overcharging can lead to problems such as battery heating, accelerated decomposition of the electrolyte, and aging of the plates, seriously affecting the battery life. Undercharging will prevent the battery capacity from being fully utilized. Long-term undercharging can also lead to battery sulfation and reduce battery performance. Therefore, during the charging process, it is necessary to strictly follow the battery manual and the parameter Settings of the charger to avoid overcharging and undercharging. At the same time, it is recommended to appropriately extend the float charging time by 0.5 to 1 hour after the battery is fully charged to ensure that the battery is completely charged.

Charging environment requirements

The charging site should be well-ventilated. Charging in a confined space should be avoided as lead-acid batteries produce flammable gases such as hydrogen during the charging process. Excessive accumulation may cause an explosion hazard. The charging environment temperature should be controlled between 5 and 40℃. Both excessively high and low temperatures will affect the charging efficiency and battery life. In addition, the charging equipment should be placed in a dry and stable area to avoid vibration and impact.

(4) Storage and Maintenance

When the lead-acid battery of a forklift needs to be stored for a long time, it should be fully charged first, and then a supplementary charge should be carried out every half a month to prevent the battery from being discharged due to self-discharge. The storage environment should be dry, cool and well-ventilated, avoiding direct sunlight and damp conditions. At the same time, it should be kept away from heat sources and corrosive substances. If conditions permit, the battery can be removed from the forklift for storage, and the appearance of the battery and the level of the electrolyte should be checked regularly to ensure that the battery is in good condition.

3. Inspection of Lead-Acid Batteries in Forklifts

(1) Voltage detection

Static voltage detection

Static voltage refers to the voltage of a battery when it has been left to stand for a period of time (generally 2 to 4 hours) without any charging or discharging operations. Measuring the static voltage of a battery with a multimeter can initially determine the battery's power state. Generally speaking, a static voltage of around 2.1V for a single-cell battery indicates that the battery is fully charged. If the voltage is lower than 2.0V, it indicates that the battery power is insufficient and needs to be charged. When the voltage is lower than 1.8V, the battery may be faulty and further inspection is required.

Dynamic voltage detection

Dynamic voltage detection is the voltage measurement carried out during the battery discharge process. When the forklift is in normal operation, use professional voltage detection equipment to monitor the voltage changes of the battery. If during the discharge process, the battery voltage drops too rapidly or the voltage difference between individual cells exceeds 0.1V, it indicates that the battery may have problems such as capacity imbalance or plate aging, and in-depth detection and analysis are required.

(2) Capacity Detection

Discharge test method

The discharge test method is the most direct and accurate capacity detection method. The battery is discharged at a constant current through a dedicated discharge device, and the discharge time and voltage changes of the battery are recorded. The actual capacity of the battery can be calculated based on the discharge time and discharge current. Generally speaking, the actual capacity of a new battery should not be less than 95% of its rated capacity. As the usage time increases, when the battery capacity drops below 80% of the rated capacity, it is necessary to consider replacing the battery.

Internal resistance detection method

The internal resistance of the battery is one of the important parameters reflecting the performance of the battery. The magnitude of internal resistance is closely related to the capacity, lifespan and charging and discharging performance of the battery. Use a professional battery internal resistance tester to measure the internal resistance of the battery. Generally speaking, the internal resistance of a new battery is relatively small. As the battery ages and its performance declines, the internal resistance will gradually increase. When the internal resistance of a battery exceeds a certain threshold, it indicates that the battery's performance has seriously declined and needs to be replaced. The normal range of internal resistance varies among different models and specifications of batteries. For specific details, you can refer to the technical parameters provided by the battery manufacturer.

(3) Appearance and structure inspection

Regularly inspect the appearance of the battery to see if there is any damage, deformation, leakage or other conditions on the battery casing. If the battery casing is found to be damaged, its use should be stopped immediately to prevent electrolyte leakage from causing environmental pollution and equipment damage. At the same time, check whether the battery terminals are corroded or loose and whether the connecting wires are firm. Corrosion of the terminal post will increase the contact resistance, resulting in a decrease in charging and discharging efficiency. Loose connecting wires may cause sparking, posing a safety hazard. For corroded terminals, sandpaper can be used for grinding and a special battery terminal protector can be applied. For loose connecting wires, they should be tightened in time to ensure a firm connection.

(4) Fault Diagnosis and Analysis

When the battery experiences abnormal conditions, such as severe heating during charging, significantly shortened discharge time, or unstable voltage, fault diagnosis and analysis are required. First, based on the fault phenomenon and detection data, determine the possible locations where the fault may occur, such as the plates, electrolyte, connecting wires, chargers, etc. Then, by using the method of checking one by one, the cause of the fault is identified and corresponding maintenance measures are taken. If you are unable to determine the cause of the fault or carry out repairs by yourself, you should promptly contact professional battery repair personnel or technical support from the manufacturer to prevent the fault from expanding due to improper operation.

4. Replacement of Lead-acid Batteries in Forklifts

(1) Judgment of replacement timing

When the battery shows the following conditions, replacement should be considered: First, the battery capacity drops below 80% of the rated capacity and cannot meet the normal operation requirements of the forklift; The second is that the battery has severe leakage, plate deformation, short circuit and other faults, which cannot be restored to normal performance through repair. Thirdly, the battery's service life has reached the manufacturer's specified lifespan. Although it may still be usable, its performance and reliability have significantly declined, posing a safety hazard.

(2) Preparations before replacement

Choose the appropriate battery

According to the model, power and operation requirements of the forklift, select the matching lead-acid battery. The rated voltage, capacity, size and other parameters of the new battery should be consistent with those of the original battery to ensure smooth installation and use. At the same time, choose reliable and reputable brand batteries to avoid purchasing counterfeit and shoddy products.

Prepare to change the tools and protective equipment

To replace the battery, tools such as wrenches and screwdrivers are needed. At the same time, protective gloves, goggles, aprons and other protective equipment should be prepared to prevent the electrolyte from splashing and injuring people. In addition, containers for receiving the electrolyte should also be prepared to properly handle any possible leakage during the replacement process.

Safety measures

Before replacing the battery, the power switch of the forklift should be turned off first, and the key should be unplugged to ensure that the forklift is in a power-off state. If conditions permit, the forklift can be parked in a flat, dry and well-ventilated area, and the wheel stops should be used to fix the forklift to prevent it from sliding. At the same time, it is necessary to ensure that there are no fire sources or flammable materials around the replacement site to avoid fire and explosion accidents.

(3) Replace the operation process

Disassemble the old battery

First, remove the negative terminal connection wire of the battery, and then remove the positive terminal connection wire to avoid a short circuit. Use a wrench to loosen the bolts of the battery bracket and carefully remove the old battery from the forklift. During the removal process, be careful to avoid excessive tilting of the battery to prevent electrolyte leakage. If the old batteries are heavy, forklifts or other lifting equipment can be used to assist in their transportation.

Install a new battery

Place the new battery steadily at the battery installation position on the forklift, adjust the direction and position of the battery properly, and ensure that the battery is correctly connected to the installation bracket and connecting wires. Use a wrench to tighten the bolts of the battery fixing bracket and secure the battery. Then, first connect the positive terminal connection wire of the battery, and then connect the negative terminal connection wire. Make sure the connection is firm and the contact is good.

Inspection and Debugging

After installation is completed, check whether the battery connection lines are connected correctly and whether the fixed brackets are firm. Turn on the power switch of the forklift, check whether the battery voltage is normal, and whether the forklift can start and operate normally. If any abnormal situation is found, the machine should be stopped immediately for inspection and troubleshooting.

(4) Disposal of used batteries

Old lead-acid batteries are classified as hazardous waste, containing harmful substances such as sulfuric acid. Random discarding will cause serious pollution to the environment. Therefore, it must be properly handled in accordance with relevant regulations. Old batteries can be handed over to qualified used battery recycling enterprises for recycling and processing to ensure that used batteries are safely and environmentally friendly disposed of, avoiding harm to the environment and human health.

5. Conclusion

The maintenance, inspection and replacement of lead-acid batteries in forklifts are key links to ensure the normal operation of forklifts, improve work efficiency and reduce operating costs. Through scientific and reasonable daily maintenance, the service life of the battery can be effectively prolonged. Accurate detection can promptly identify problems with the battery and take corresponding measures to repair or replace it. Correct replacement operations and the disposal of used batteries not only ensure the safe operation of forklifts but also protect the environment. Relevant practitioners should fully recognize the significance of maintaining, inspecting and replacing lead-acid batteries, strictly follow the operating procedures and standards, continuously improve their professional skills and management levels, and provide reliable power support for the logistics and warehousing operations of enterprises.