News

Abstract

This article focuses on the common faults of lead-acid batteries in forklifts and systematically expounds the fault diagnosis process and rapid repair methods. Through the analysis of the causes of typical faults such as abnormal battery charging and discharging, capacity decline, and plate sulfation, combined with scientific diagnostic methods and practical maintenance experience, targeted repair plans are proposed, aiming to help forklift maintenance personnel improve the efficiency of fault handling, extend the service life of lead-acid batteries, and reduce the operation and maintenance costs of enterprise equipment.

1. Introduction

Lead-acid batteries occupy an important position in the power system of forklifts due to their advantages such as low cost and good high-current discharge performance. However, due to frequent charging and discharging, complex usage environment and other factors, forklift lead-acid batteries frequently malfunction. Timely and accurate diagnosis and repair of faults are of great significance for ensuring the normal operation of forklifts and improving the efficiency of logistics operations. This article will delve deeply into the fault diagnosis and rapid repair techniques of lead-acid batteries in forklifts, providing practical technical guidance for the industry.

2. Common Fault Types and Causes of Lead-Acid Batteries in Forklifts

(1) Abnormal charging and discharging

Abnormal voltage increase during charging: During the charging process, if the battery voltage rises rapidly and far exceeds the normal range, it may be caused by excessively high electrolyte density, sulfation of the plates, or an open circuit inside the battery. Excessive density of the electrolyte will lead to an increase in the internal resistance of the battery, causing the voltage to rise faster. After vulcanization of the plates, the active material decreases and the resistance increases, which can also cause abnormal voltage. An open circuit inside the battery will cause local current concentration, resulting in an increase in voltage.

Rapid voltage drop during discharge: When a forklift is in operation, the battery voltage drops rapidly and cannot maintain normal operation. This is usually due to the shedding of active materials on the battery plates, insufficient electrolyte, or battery aging. The shedding of active substances on the plates will reduce the substances involved in the electrochemical reaction and lower the battery capacity. Insufficient electrolyte will affect ion conduction, leading to a decline in the battery's discharge performance. Battery aging causes the performance of components such as plates and separators to decline, resulting in a rapid drop in voltage during discharge.

(2) Capacity decline

Long-term over-discharge: In actual use, if a forklift frequently operates with a low battery level, causing the battery to over-discharge, it will lead to excessive consumption of active substances on the plates, gradually forming irreversible lead sulfate crystals, thereby reducing the battery capacity.

Insufficient charging: Failure to charge according to the prescribed charging time and current, or insufficient charging due to charging equipment failure, will prevent the active substances on the battery plates from being fully transformed. Long-term accumulation will cause the battery capacity to gradually decrease.

Harsh operating environment: Both excessively high and low temperatures in the forklift's working environment can affect battery capacity. High temperatures can accelerate the chemical reactions inside the battery, leading to the evaporation of the electrolyte and intensified corrosion of the plates. Low temperatures will reduce the conductivity of the electrolyte, lowering the battery's discharge capacity. If the battery is exposed to harsh environments for a long time, its capacity will significantly decrease.

(3) Plate vulcanization

Plate sulfation is a common and highly harmful fault in lead-acid batteries. The main manifestation is the formation of hard and dense white lead sulfate crystals on the surface of the plates. These crystals will hinder the normal progress of electrochemical reactions, resulting in a decrease in battery capacity and an increase in internal resistance. The causes of sulfation on the plates mainly include: when the battery is in a discharged or semi-discharged state for a long time, a large amount of lead sulfate crystallizes on the plates; The electrolyte level is too low, exposing the upper part of the plate to the air, where it undergoes an oxidation reaction with oxygen and then reacts with sulfuric acid to form lead sulfate crystals. The excessively high density of the electrolyte accelerates the formation and crystallization process of lead sulfate.

(4) Battery leakage

Shell damage: During the operation of the forklift, the battery shell may be damaged due to reasons such as collision and squeezing, causing the electrolyte to leak. In addition, the aging and poor quality of the battery casing material can also easily lead to cracks, causing leakage problems.

Poor sealing of the terminal post: If the sealing between the terminal post and the battery casing is not tight, during the battery charging and discharging process, changes in internal pressure will cause the electrolyte to seep out from the poorly sealed area, resulting in leakage.

3. Fault Diagnosis Methods for Forklift Lead-Acid Batteries

(1) Visual inspection

Check the casing: Carefully examine the battery casing for any damage, cracks, deformations, etc., and observe if there are any residual traces of electrolyte on the surface of the casing. If the shell is found to be damaged, it is necessary to further inspect whether the internal plates and partitions are damaged.

Check the terminal posts: Examine whether there is any corrosion or loosening on the terminal posts and whether the contact between the terminal posts and the connecting wires is good. Corroded terminals will increase contact resistance and affect the charging and discharging performance of the battery. Loose poles may cause the connection parts to heat up and even lead to fire accidents.

Check the electrolyte level: Open the battery cover and observe whether the electrolyte level height is within the specified scale range. If the liquid level is too low, it may be caused by the evaporation or leakage of the electrolyte. Further investigation of the cause is needed, and distilled water or special lead-acid battery electrolyte should be replenished in time.

(2) Voltage detection

Static voltage measurement: When the battery has not undergone charging or discharging operations, use a multimeter to measure the terminal voltage of the battery. Under normal circumstances, the static voltage of a single lead-acid battery should be around 2.1V. If the measured value is significantly lower than this standard, it indicates that the battery may have problems such as over-discharge, sulfation of the plates or internal short circuit.

Dynamic voltage measurement: During the charging or discharging process of a battery, measure the changes in the terminal voltage of the battery. When charging, the voltage should gradually increase and reach the specified float charging voltage value after being fully charged. When discharging, the voltage should drop slowly. If during the charging or discharging process, the voltage shows abnormal fluctuations or does not change according to the normal pattern, it can be initially determined that the battery is faulty and further detection is required.

(3) Electrolyte testing

Density measurement: Use a hydrometer to measure the density of the electrolyte. The density standards of the electrolyte vary slightly among different types and specifications of lead-acid batteries. Generally speaking, for a fully charged lead-acid battery, the density of the electrolyte is around 1.28g/cm³ at 25℃. By measuring the density of the electrolyte, the charging state of the battery and the degree of sulfation of the plates can be determined. If the density of the electrolyte is too low, it may be due to excessive battery discharge or sulfation of the plates. If the density is too high, it might be due to excessive charging current or excessive evaporation of water in the electrolyte.

pH detection: Use pH test paper or a dedicated pH detector to test the pH of the electrolyte. Under normal circumstances, the electrolyte of lead-acid batteries is acidic, with a pH value ranging from 1 to 2. If the pH value of the electrolyte abnormally rises, it indicates that the acidity of the electrolyte has weakened. This might be due to the mixture of alkaline substances in the electrolyte or abnormal chemical reactions occurring inside the battery, which requires prompt handling.

(4) Internal resistance detection

Measure the internal resistance of the battery using a professional battery internal resistance tester. Internal resistance is one of the important indicators for measuring battery performance. An increase in internal resistance means an increase in the internal resistance of the battery, which will lead to a decrease in battery charging and discharging efficiency and a reduction in capacity. Generally speaking, the internal resistance of a new battery is relatively small. As the usage time increases, the internal resistance will gradually increase. When the internal resistance of the battery exceeds the specified threshold, it indicates that the battery performance has severely declined and needs to be repaired or replaced.

4. Quick Repair Methods for Lead-Acid Batteries in Forklifts

(1) Repair of abnormal charging and discharging

Repair of abnormal voltage increase during charging: If it is caused by an excessively high density of the electrolyte, slowly add distilled water to the battery while stirring continuously until the density of the electrolyte drops to the normal range. For the abnormal voltage caused by sulfation of the plates, the low-current long-time charging method can be adopted for repair. That is, charge at a current of 0.1C (C is the rated capacity of the battery), and extend the charging time to 1.5-2 times the normal charging time, so that the lead sulfate crystals on the plates gradually dissolve. If an open circuit is detected inside the battery, the battery casing needs to be opened, the open circuit area carefully inspected, and damaged plates, connecting wires and other components repaired or replaced.

Repair of rapid voltage drop during discharge: If the capacity drops due to the shedding of active material on the plates, for cases where the shedding is not severe, the electrolyte in the battery can be drained out, and the interior of the battery can be repeatedly rinsed with distilled water to remove the shed active material. Then, electrolyte of appropriate density can be recharged. If the electrolyte is insufficient, distilled water or special electrolyte should be replenished in time. After replenishment, normal charging should be carried out. For severely aged batteries, it is recommended to replace them with new ones.

(2) Capacity decline repair

For long-term over-discharge and insufficient charging: The pulse repair method is adopted. The pulse repair instrument restores the battery capacity by outputting high-frequency pulse current to the battery, breaking the lead sulfate crystals on the plates and converting them back into active substances. Generally, 2 to 3 consecutive pulse repair cycles are required, each of which includes steps such as charging, pulse repair and discharging.

Improve the usage environment: Equip the forklift with an appropriate battery insulation box or cooling device to prevent the battery from operating in an environment with excessively high or low temperatures. In high-temperature environments, measures such as ventilation and shading can be taken to lower the battery temperature. In a low-temperature environment, a heating device can be used to preheat the battery to ensure it operates within an appropriate temperature range.

(3) Plate vulcanization repair

Chemical repair method: Add a special plate sulfation repair solution to the battery. The chemical components in the repair solution can undergo a chemical reaction with lead sulfate crystals, causing them to dissolve and transform into soluble lead salts. Then, through the normal charging process, the lead salts are converted into active substances. When using the chemical repair method, it is necessary to strictly follow the instructions for the use of the repair solution, pay attention to safety protection, and avoid the repair solution coming into contact with the skin and eyes.

Physical repair method: In addition to the low-current long-term charging method mentioned earlier, the ultrasonic repair method can also be adopted. Ultrasonic waves can generate high-frequency vibrations, which act on the lead sulfate crystals on the plates, breaking and dissolving them, thereby achieving the purpose of repairing the sulfation of the plates. Ultrasonic repair method requires the use of professional ultrasonic repair equipment. The operation is relatively complex and the cost is high, but the repair effect is good.

(4) Battery leakage repair

Repair of casing damage: For minor casing damage, a special battery casing repair adhesive can be used for repair. First, clean the damaged area thoroughly, then apply the repair glue and wait for it to cure. If the casing is severely damaged, a new battery casing should be replaced. When replacing the casing, carefully remove the internal components such as the plates and separators of the battery, install them in the new casing, and refill with electrolyte of appropriate density.

Repair of poor terminal post seal: Remove the terminal post connection wire, clean the corrosion and impurities on the terminal post and the sealing part, then reapply the sealant, install the terminal post connection wire and ensure a firm connection. After the repair, check if the battery still leaks. If necessary, it can be resealed.

5. Maintenance and Care Suggestions for Forklift Lead-Acid Batteries

(1) Reasonable use

Avoid excessive discharge: During forklift operation, closely monitor the battery power indicator. When the power drops to around 20% to 30%, charge it promptly to prevent excessive discharge. Excessive discharge can seriously affect battery life and increase the probability of failure.

Control working hours: Arrange the operation time of forklifts reasonably to avoid prolonged continuous work. Long-term high-current discharge will cause the battery to heat up and accelerate its aging. It is recommended to let the battery rest for 15 to 30 minutes every 1 to 2 hours of operation.

(2) Standardize charging

Select the appropriate charger: Use a dedicated charger that matches the battery specifications and strictly follow the charger's instructions for charging. Lead-acid batteries of different types and specifications have different requirements for charging voltage, current and charging time. Using an incompatible charger may damage the battery.

Follow the charging norms: Adopt the correct charging method, generally using the constant current - constant voltage charging method. First, charge with a constant current. When the battery voltage reaches a certain value, switch to constant voltage charging until the battery is fully charged. During the charging process, avoid overcharging and undercharging. Stop charging promptly once the battery is fully charged.

(3) Regular inspection and maintenance

Daily inspection: Conduct a visual inspection of the battery every day, checking the condition of the casing, terminal posts, and electrolyte level, etc. Regularly measure the voltage of the battery and the density of the electrolyte to keep track of the battery's working condition.

Deep maintenance: Conduct a deep maintenance of the battery every 3 to 6 months, including cleaning the dust and corrosion on the battery surface, checking the tightness of the connection wires, and adjusting the density of the electrolyte, etc. For batteries that have been in use for a long time, a charge-discharge cycle test can be conducted to evaluate the battery capacity and performance.

6. Conclusion

Fault diagnosis and rapid repair of lead-acid batteries in forklifts are the key links to ensure the normal operation of forklifts. Through the analysis of the causes of common fault types and the application of scientific diagnostic methods, the reasons for battery faults can be accurately determined, and targeted repair measures can be taken. At the same time, strengthening the daily maintenance and care of batteries, using them reasonably and charging them in a standardized manner can effectively extend the service life of batteries, reduce the frequency of faults, and lower the operation and maintenance costs of enterprise equipment. With the continuous development of technology, more advanced fault diagnosis and repair technologies will be applied to the field of forklift lead-acid batteries in the future, further enhancing the reliability and utilization efficiency of the batteries.