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Introduction

As an indispensable handling equipment in modern logistics and industrial production, the performance and reliability of lead-acid batteries, one of the power sources of forklifts, are of vital importance. The health condition of lead-acid batteries directly affects the working efficiency, operational stability and service life of forklifts. Regular comprehensive and detailed inspection of the lead-acid batteries in forklifts can help identify potential problems in a timely manner, take effective maintenance measures, ensure that the batteries are in good working condition, and thus guarantee the normal operation of the forklifts. This article will provide an in-depth interpretation of each item in the regular inspection of lead-acid batteries in forklifts, offering professional guidance and reference for relevant personnel.

Visual inspection

Battery casing

Integrity check: Carefully inspect the battery casing for any damage, cracks or deformations. Even the tiniest cracks can lead to electrolyte leakage, which not only corrodes the surrounding equipment and environment but also affects the chemical reactions inside the battery, reducing its performance. For instance, during the daily use of forklifts, the battery casing may be damaged due to collisions or improper operation. Therefore, the integrity of the casing should be given special attention during each inspection.

Cleanliness inspection: The surface of the battery casing should be kept clean, free of dust, dirt and electrolyte residue accumulation. Dust and dirt can affect the heat dissipation of the battery, causing its temperature to rise and accelerating its aging. Residual electrolyte may corrode the casing and further damage the battery. Regularly wipe the battery casing with a clean damp cloth to ensure it is clean.

Battery terminal

Corrosion inspection: Check if there is any corrosion on the battery terminals. Corrosion is usually manifested as white or green powder-like substances on the surface of the terminals. These corrosive substances will increase the resistance between the terminals and the connecting wires, resulting in poor current transmission and affecting the charging and discharging performance of the battery. Once corrosion is detected, it should be promptly cleaned with a dedicated cleaner or baking soda water, and then an appropriate amount of protective grease should be applied to prevent further corrosion.

Connection tightness check: Ensure that the battery terminals are firmly connected to the connection wires without any signs of looseness. Loose connections can cause poor contact and generate electric sparks. This not only poses a safety hazard but also leads to local overheating of the battery, damaging it. Use tools such as wrenches to regularly check and tighten the terminal connection bolts to ensure the reliability of the connection.

Battery cover plate and exhaust hole

Cover plate integrity inspection: The battery cover plate should be free from damage or deformation and have a good seal. The main function of the cover plate is to prevent foreign objects from entering the battery and maintain the sealing inside the battery at the same time. If the cover plate is damaged, dust and impurities may enter the battery, affecting the chemical reaction of the battery and reducing its performance.

Check the patency of the exhaust hole: The function of the exhaust hole is to discharge the gases (such as hydrogen and oxygen) produced by the battery during charging and discharging. Regularly check whether the exhaust holes are unobstructed to avoid blockage. If the exhaust hole is blocked, the gas inside the battery cannot be discharged, which will cause the internal pressure of the battery to rise, and may lead to serious safety accidents such as the battery casing cracking or even exploding. You can use tools such as thin iron wire to gently unclog the exhaust hole, but be careful not to damage the internal structure of the exhaust hole during the operation.

Electrical performance testing

Voltage detection

Single-cell battery voltage detection: Use professional tools such as multimeters to measure the voltage of each single-cell battery. Lead-acid batteries are usually composed of multiple 2V individual cells connected in series. For instance, a common forklift battery pack might be 24V (12 cells), 36V (18 cells), 48V (24 cells), etc. After the battery is fully charged and has been left to stand for a period of time (generally 1 to 2 hours), the open-circuit voltage of a single battery should be around 2.1V to 2.15V. If the voltage of a single cell is significantly lower or higher than this range, it indicates that there may be problems with the cell, such as internal short circuit or sulfation of the plates.

Battery pack total voltage detection: Measure the total voltage of the battery pack and compare the measured value with the nominal voltage of the battery pack. During the charging process, the total voltage of the battery pack will gradually rise. When it approaches the terminal charging voltage set by the charger, it indicates that the battery is nearly fully charged. During the discharge process, the total voltage of the battery pack will gradually decrease. When it drops to the minimum allowable discharge voltage of the battery, discharge should be stopped; otherwise, it will cause irreversible damage to the battery. For instance, for a 48V forklift battery pack, the minimum allowable discharge voltage is generally around 42V to 44V. The specific value can be referred to the technical parameters provided by the battery manufacturer. By monitoring the total voltage of the battery pack, one can understand the charging status and discharging conditions of the battery and determine whether it is working normally.

Internal resistance detection

The importance of internal resistance: Internal resistance is one of the important indicators for measuring the health status of batteries. As the battery is used and ages, its internal resistance will gradually increase. An increase in internal resistance means that the resistance loss inside the battery rises, generating more heat during charging and discharging, which leads to a decline in battery performance and a reduction in capacity. At the same time, excessive internal resistance may also affect the charging and discharging speed of the battery, prolonging the charging time and causing insufficient output power during discharging.

Detection method: A professional internal resistance tester can be used to measure the internal resistance of the battery. The normal internal resistance range varies among different types and capacities of batteries. Generally speaking, the internal resistance of new lead-acid batteries is relatively small. As the usage time increases, the internal resistance will gradually increase. When the internal resistance of a battery exceeds the upper limit value specified by the manufacturer, it indicates that the battery may have aged severely and requires maintenance or replacement. For instance, for a lead-acid battery with a capacity of 200Ah, the internal resistance of a new battery may range from a few milliohms to over ten milliohms. However, when the internal resistance increases to several tens of milliohms, the battery's performance will significantly decline.

Capacity detection

The significance of capacity detection: Battery capacity reflects the battery's ability to store and release electrical energy and is a key indicator for measuring battery performance. Regularly checking the battery capacity can help understand the actual usage of the battery and determine whether it meets the working requirements of the forklift. As the number of battery uses increases, its capacity will gradually decline. When the battery capacity decays to a certain extent (such as below 80% of the rated capacity), it may be necessary to maintain or replace the battery to ensure the normal operation of the forklift.

Detection method: The commonly used capacity detection method is the constant current discharge method. After fully charging the battery, discharge it at a constant current. Record the discharge time and the voltage changes during the discharge process. The actual capacity of the battery can be calculated based on the discharge current and discharge time. For instance, if a battery is discharged at a current of 20A for 10 hours, the actual capacity of the battery is 20A × 10h = 200Ah. In actual detection, to ensure the accuracy of the detection results, it is necessary to strictly control conditions such as discharge current and ambient temperature. Meanwhile, as the capacity testing process is rather time-consuming, it generally does not need to be carried out frequently. Based on the battery's usage and the manufacturer's recommendations, capacity testing can be conducted at regular intervals (such as half a year or one year).

Electrolyte detection

Electrolyte level detection

Liquid level standard: For open-type lead-acid batteries, the electrolyte level needs to be checked regularly. The electrolyte level should be maintained between the highest and lowest levels marked on the battery casing. Generally speaking, the electrolyte level should be about 10mm to 15mm higher than the top of the plates. If the electrolyte level is too low, the plates will be partially exposed to the air, causing sulfation of the plates and reducing the battery's capacity and lifespan. If the liquid level is too high, it may cause the electrolyte to overflow during the battery charging and discharging process, corroding the equipment and the environment.

When the electrolyte level is found to be too low, distilled water or dedicated lead-acid battery replenishment fluid should be replenished in a timely manner. Never add tap water or other water containing impurities, as the impurities in tap water may have a chemical reaction with the electrolyte, affecting the battery performance. When replenishing the electrolyte, it should be added slowly to avoid splashing. After the addition is completed, the battery casing should be wiped with a clean cloth to ensure there is no electrolyte residue.

Electrolyte density detection

The relationship between density and battery state: The density of the electrolyte is closely related to the charging state of the battery. During the battery charging process, the concentration of sulfuric acid in the electrolyte gradually increases and its density rises. During the discharge process, sulfuric acid participates in chemical reactions, with its concentration decreasing and density dropping. By detecting the density of the electrolyte, the charging status and health condition of the battery can be determined. Generally speaking, when a lead-acid battery is fully charged, the density of the electrolyte is around 1.28g/cm³ at 25℃. The standard values of electrolyte density for batteries produced by different manufacturers may vary slightly. For specific values, please refer to the technical data provided by the battery manufacturer.

Detection method: Use a hydrometer to measure the density of the electrolyte. Insert the pipette of the hydrometer into the electrolyte, draw an appropriate amount of electrolyte to make the float of the hydrometer float up, and read the scale value on the float that is level with the liquid surface, which is the density of the electrolyte. It should be noted that the density of the electrolyte varies with temperature. For every 1℃ increase in temperature, the density decreases by approximately 0.0007g/cm³. Therefore, when measuring the density of the electrolyte, the temperature of the electrolyte should be measured simultaneously, and the measurement results should be corrected based on the temperature.

Electrolyte quality inspection

Impurity detection: Check whether the electrolyte contains impurities such as metal particles, precipitates, etc. The presence of impurities can affect the conductivity and chemical reactions of the electrolyte, leading to a decline in battery performance. The presence of impurities can be initially determined by observing the transparency and color of the electrolyte. Under normal circumstances, the electrolyte should be a colorless, transparent or slightly yellowish liquid. If the electrolyte becomes turbid or has obvious sediment, it indicates that impurities may exist and the electrolyte needs to be filtered or replaced.

pH test: The electrolyte of lead-acid batteries is acidic, and its pH value is generally between 0 and 1. Use pH test paper or a pH meter and other tools to test the acidity or alkalinity of the electrolyte to ensure it is within the normal range. If the pH value of the electrolyte undergoes abnormal changes, it may indicate an internal fault in the battery, such as plate corrosion or electrolyte contamination. Timely investigation and handling are necessary.

Other testing items

Charge and discharge characteristic detection

Charging characteristic detection: During the charging process, parameters such as the charging current, charging voltage and charging time of the battery are monitored. Under normal circumstances, at the beginning of battery charging, the charging current is relatively large. As charging proceeds, the charging current gradually decreases and the charging voltage gradually increases. When the battery is nearly fully charged, the charging current will become very small and the charging voltage will reach the terminal charging voltage set by the charger. If during the charging process, it is found that the charging current is abnormally large or small, the charging voltage rises too fast or too slow, or the charging time is too long, it indicates that there may be problems with the battery, such as internal short circuit, sulfation of the plates, or charger failure.

Discharge characteristic detection: By simulating the actual working conditions of forklifts, discharge tests are conducted on the battery to observe the changes in parameters such as discharge voltage, discharge current, and discharge time of the battery. During the discharge process, the discharge voltage of the battery should gradually decrease, but the rate of decrease should be relatively stable. If there is a sudden drop in voltage or unstable discharge current during the discharge process, it indicates that the battery may have problems such as insufficient capacity or unbalanced individual cells. Through the detection of charge and discharge characteristics, the performance status of the battery can be comprehensively understood, providing a basis for the maintenance and management of the battery.

Internal structure inspection of the battery (regular disassembly inspection)

Plate inspection: For batteries that have been in use for a long time or have shown abnormal conditions, under the guidance of professionals, the battery casing can be opened to check the condition of the plates. Observe whether the plates are deformed, bent or broken, and whether the active substances on the surface of the plates have fallen off or corroded. The plates are the key components for batteries to achieve the mutual conversion between chemical energy and electrical energy. The damage of the plates will directly lead to the decline in battery performance or even failure. If serious problems with the plates are found, the entire battery usually needs to be replaced.

Partition inspection: The partition is located between the positive and negative plates, serving to isolate the positive and negative plates and prevent short circuits. Check whether the separator has any damage, perforation or other conditions. The integrity of the separator is crucial for the normal operation of the battery. If the separator is damaged, the positive and negative plates may short-circuit, causing the battery to discharge instantaneously and leading to safety accidents. Once any problem with the partition is found, it should be replaced in time.

Detection cycle and records

The detection cycle is determined.

According to the frequency of use: For frequently used forklifts, it is recommended to conduct an appearance inspection and voltage test once a week or every two weeks, an electrolyte level and density test once a month, an internal resistance test and charge and discharge characteristic test once a quarter, and a capacity test and battery internal structure inspection once every six months or once a year (if necessary). For forklifts with lower usage frequency, the inspection cycle can be appropriately extended. However, at least one appearance inspection and voltage test should be conducted once a month, one electrolyte related test every two months, and one other important item test every six months.

According to the battery's service life: In the initial stage of use, the performance of a new battery is relatively stable, and the testing cycle can be appropriately extended. As the battery's service life increases, its performance gradually declines and the probability of failure increases. Therefore, the inspection cycle should be shortened. Generally speaking, after the battery has been in use for 1 to 2 years, the inspection frequency should be gradually increased. Especially when approaching the expected service life of the battery, more frequent inspections should be carried out to promptly identify potential problems and prevent battery malfunctions from affecting the normal operation of the forklift.

The Importance of Inspection Records

Record content: For each inspection, the inspection data and the problems found should be recorded in detail. The recorded contents include the inspection date, inspection items, inspection results, battery appearance condition, forklift usage situation, etc. For example, in the voltage detection record, the voltage value of each individual battery and the total voltage value of the battery pack should be recorded. In the electrolyte density detection record, the measured electrolyte density value, the temperature during measurement, and the corresponding corrected density value should be recorded. For the problems found, such as battery casing damage, terminal corrosion, abnormal voltage, etc., a detailed description of the specific circumstances and location of the problem should be provided.

Data analysis and Application: By analyzing long-term detection records, the changing trends of battery performance can be understood, potential problems can be identified in a timely manner, and corresponding maintenance measures can be taken. For instance, if it is found that the internal resistance of the battery is gradually increasing and its capacity is gradually decreasing, the maintenance or replacement plan of the battery can be arranged in advance to avoid battery failure during the operation of the forklift. Meanwhile, the test records can also serve as a basis for evaluating the quality and lifespan of batteries, providing a reference for choosing the appropriate battery brand and model.

Conclusion

Regular comprehensive and detailed inspections of lead-acid batteries in forklifts, covering appearance checks, electrical performance tests, electrolyte tests, and other related inspection items, are key measures to ensure the normal operation of the batteries, extend their service life, and guarantee the efficient operation of forklifts. By reasonably determining the inspection cycle, carefully keeping inspection records, and conducting in-depth analysis of the inspection data, problems existing in the battery can be identified in a timely manner, and targeted maintenance and management measures can be taken, thereby reducing the operating cost of forklifts, improving production efficiency, and providing reliable power support for the enterprise's logistics and production activities. In actual operation, relevant personnel should strictly follow the testing standards and operating procedures for testing, continuously accumulate experience, improve the testing level, and ensure that the lead-acid batteries of forklifts are always in good working condition.