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In the modern logistics and warehousing industry, forklifts, as important handling equipment, undertake key tasks such as loading and unloading goods, stacking and short-distance transportation. As the power core of electric forklifts, the performance of lead-acid batteries directly affects the working efficiency, service life and operating costs of forklifts. However, during long-term use, lead-acid batteries are bound to encounter various faults. A thorough understanding of these common faults and their efficient solutions is of great significance for ensuring the normal operation of forklifts and reducing maintenance costs.

1. Common Faults and Efficient Solutions

(1) Battery capacity decline

Fault manifestation: During the operation of the forklift, after the battery is fully charged, the working time is significantly shortened and it cannot reach the normal driving range. The forklift that could work for 8 hours when fully charged can now only operate for 4 to 5 hours.

Cause analysis

Plate sulfation: If the battery is in a state of insufficient charging for a long time or not charged in time after discharging, a layer of white and hard lead sulfate crystals will form on the surface of the plates. These crystals will hinder the chemical reaction between the electrolyte and the plates, thereby reducing the battery capacity. In addition, if the electrolyte level is too low and the upper part of the plates is exposed to the air for a long time, it is also easy to cause sulfation of the plates.

Abnormal electrolyte density: Both excessively high and low electrolyte density can affect the performance of the battery. Excessively high density will accelerate the corrosion of the plates, while too low density will reduce the battery's discharge capacity. During the use of the electrolyte, its density may change due to evaporation, leakage and other reasons. If not adjusted in time, the battery capacity will decrease.

Battery aging: As the usage time increases, the active substances on the battery plates gradually fall off, and the performance of the separators will also decline, resulting in an increase in internal resistance and a decrease in capacity of the battery.

Solution method

Dealing with plate sulfation: For batteries with mild sulfation, a method of charging with a small current for a long time can be adopted for repair. That is, charge with a current of 0.05-0.1C (C is the battery capacity) for 10-15 hours. For batteries with severe sulfation, a dedicated pulse repair instrument can be used to break the lead sulfate crystals through high-frequency pulse current and restore the activity of the plates. At the same time, it is necessary to pay attention to maintaining the normal charging of the battery and avoid over-discharging and long-term undercharging.

Adjust the density of the electrolyte: Regularly test the density of the electrolyte and measure it with a hydrometer. Under normal circumstances, the density of the electrolyte should be between 1.28 and 1.30g/cm³. If the density is too high, distilled water can be added for dilution.

Replace aged batteries: When batteries are severely aged and their capacity cannot be increased through repair, new batteries should be replaced in a timely manner. When choosing a new battery, it is necessary to select a product with reliable quality and appropriate capacity based on the model and usage requirements of the forklift.

(2) Abnormal battery charging

Fault manifestations: During the charging process, the battery overheats severely, the charging voltage is too high or too low, the charging time is too long, and in some cases, it cannot be charged at all.

Cause analysis

Charger failure: Damage to internal components of the charger, such as breakdown of the rectifier diode, failure of the filter capacitor, or malfunction of the charging control circuit, can cause unstable charging voltage and current, making it impossible to charge the battery normally.

Internal short circuit of the battery: Short circuit of the plates is a common cause of internal short circuit in batteries. It may be due to excessive shedding of the active material on the plates, which deposits at the bottom of the battery and causes the positive and negative plates to be connected. It could also be that the partition is damaged, causing the positive and negative plates to come into direct contact. In addition, loose or oxidized connection strips inside the battery can also cause poor contact, leading to abnormal charging.

Charging line issues: Aging, damage, poor contact, etc. of the charging line can lead to a reduction or interruption of the charging current. Loose or oxidized charging plugs and sockets can also affect the charging effect.

Solution method

Inspect and repair the charger: Use tools such as a multimeter to check whether the output voltage and current of the charger are normal. If a charger malfunction is found, it should be repaired or replaced according to the specific situation. For simple component damage, the corresponding components can be replaced. For complex circuit faults, it is recommended that they be repaired by professional technicians.

Check for internal short circuits in the battery: Open the battery cover and inspect the plates for any obvious signs of short circuits, such as a large amount of sediment at the bottom of the plates or damaged separators. If a short circuit of the plates is found, the electrolyte in the battery can be poured out, the plates and the interior of the battery can be rinsed with distilled water to remove the deposits, and then the damaged separators can be replaced. If the short circuit is severe and cannot be repaired, the battery needs to be replaced. At the same time, check whether the internal connection strips of the battery are loose or oxidized. If there are any problems, tighten and clean them in time.

Repair the charging circuit: Check if the charging circuit is aged or damaged. If so, replace it in time. Make sure that the charging plugs and sockets are firmly connected and there is no oxidation. For areas with poor contact, sandpaper can be used for grinding or conductive paste can be applied to improve the contact effect.

(3) Battery leakage

Fault manifestations: There is electrolyte overflow on the surface of the battery casing, there is liquid residue at the bottom or side of the battery, and there is a pungent smell in the battery compartment.

Cause analysis

Battery casing damage: During the operation of forklifts, the battery may be subjected to external forces such as collision and compression, causing casing damage and electrolyte leakage. In addition, if the battery casing is exposed to high temperatures, corrosion and other environments for a long time, it will also accelerate the aging and damage of the casing.

Sealing aging: The sealing strips, exhaust valves and other sealing components between the battery cover and the casing will gradually age and harden as the usage time increases, losing their sealing performance and causing electrolyte leakage.

Excessive electrolyte addition: When replenishing the electrolyte, if too much is added, exceeding the specified liquid level height, during the battery charging or operation process, the electrolyte will expand due to heat and overflow.

Solution method

Repair or replace the battery casing: For minor casing damage, acid-resistant materials such as epoxy resin can be used for repair. First, clean the damaged area thoroughly, then apply epoxy resin and wait for it to cure. If the casing is severely damaged and cannot be repaired, a new battery casing needs to be replaced. When replacing the casing, pay attention to choosing a product that matches the model of the primary battery and ensure correct installation.

Replace the sealing parts: Regularly inspect the sealing parts of the battery. If aged or damaged sealing strips, exhaust valves, etc. are found, replace them in time. When installing the sealing parts, apply an appropriate amount of sealant to ensure the sealing effect.

Control the amount of electrolyte added: When replenishing the electrolyte, follow the battery's user manual and use a dedicated funnel and measuring cup to accurately control the amount of electrolyte added. Generally speaking, the electrolyte level should be 10 to 15mm higher than the plates. After filling is completed, the surface of the battery should be wiped clean to prevent the residue of electrolyte.

(4) Unstable battery voltage

Fault manifestation: During the operation of the forklift, the battery voltage displayed on the dashboard fluctuates up and down, the vehicle power is unstable, and sometimes there is a phenomenon of weak acceleration.

Cause analysis

Unbalanced voltage among individual cells: Lead-acid batteries are typically composed of multiple individual cells connected in series. During use, due to performance differences and varying degrees of charging and discharging among the individual cells, voltage imbalance may occur among them. This imbalance will cause the performance of the entire battery pack to decline and the voltage to become unstable.

Loose battery connection wires: If the connection wires inside the battery pack and between the battery and the forklift's electrical system are loose, it will lead to an increase in contact resistance, resulting in voltage loss during transmission and causing unstable voltage.

Sensor failure: The voltage display on the forklift dashboard relies on the battery voltage sensor. If the sensor malfunctions, such as short circuit, open circuit, or abnormal signal transmission, it will cause the displayed voltage to be inaccurate, creating a false impression of unstable voltage.

Solution method

Equalization of individual cells: Regularly perform equalization charging on the cells, that is, charge the cells with a constant voltage higher than the normal charging voltage to make the voltages of each individual cell tend to be consistent. Generally, equalization charging should be carried out once every 2 to 3 months, with a charging time of 8 to 10 hours. For single cells with significant voltage differences, supplementary charging or replacement can be carried out separately.

Tighten the battery connection wires: Check all the connection wires inside and outside the battery pack to ensure they are firmly connected without any looseness. For loose connection wires, use appropriate tools to tighten them and check if there is any oxidation at the connection points. If so, clean them up.

Inspect the sensor: Use tools such as a multimeter to test the performance of the battery voltage sensor and check whether the input and output signals of the sensor are normal. If a sensor malfunction is detected, it should be repaired or replaced in a timely manner. At the same time, check whether the connection line between the sensor and the dashboard is normal to ensure that the signal transmission is correct.

2. Measures for Preventing Faults in Lead-Acid Batteries

(1) Correct usage method

Avoid over-discharge: During the operation of the forklift, pay attention to observing the battery power. When the power indicator approaches the minimum limit, stop working immediately and start charging. Avoid over-discharging the battery. Generally, charging should be carried out when the battery voltage drops to 80% to 85% of the rated voltage.

Reasonably control the charging time: The charging time should not be too long or too short. Too short will lead to insufficient battery charging and affect battery capacity. If it is too long, it will cause the battery to heat up and accelerate its aging. Under normal circumstances, the regular charging time is 8 to 10 hours, and the fast charging time does not exceed 3 to 4 hours.

Regular deep discharge: It is recommended to perform a deep discharge on the battery every 2 to 3 months, that is, to reduce the battery power to a lower level and then fully charge it. This can activate the active substances on the plates and extend the battery's service life.

(2) Regular maintenance and servicing

Check the electrolyte level: Check the electrolyte level at least once a week and replenish distilled water or dedicated lead-acid battery replenishment fluid in a timely manner. When replenishing the liquid, be sure to use clean tools to prevent impurities from entering the battery interior.

Clean the battery surface: Regularly wipe the battery surface with a damp cloth to remove dust, electrolyte residues, etc., to keep the battery surface clean and dry and prevent self-discharge of the battery.

Test battery performance: Every month, test parameters such as battery voltage, electrolyte density, and charge and discharge current, record the test data, analyze the trend of battery performance changes, and promptly identify potential problems and take corresponding measures.

(3) Appropriate storage environment

Temperature control: Lead-acid batteries should be stored in a dry, well-ventilated and cool environment, with the temperature maintained between 5 and 25 degrees Celsius. Both excessively high and low temperatures can affect the performance and lifespan of batteries.

Moisture-proof and anti-corrosion: Prevent the battery from being exposed to a humid environment to avoid rusting and corrosion of the battery casing and plates due to moisture. At the same time, stay away from corrosive gases and liquids, such as acids, alkalis and other chemical substances.

Lead-acid batteries, as the core component of electric forklifts, the resolution and prevention of common faults are crucial for ensuring the normal operation of forklifts. By thoroughly understanding the working principle of batteries, grasping the manifestations, causes and solutions of common faults, and taking correct usage and maintenance measures, the service life of batteries can be effectively prolonged, the working efficiency of forklifts can be improved, and operating costs can be reduced. In actual work, operators and maintenance personnel should closely monitor the condition of the battery, promptly identify and handle problems, and ensure the safe and efficient operation of the forklift.