News

In the modern logistics and warehousing field, forklifts, as indispensable handling equipment, the performance of their power source - lead-acid batteries - is of vital importance. However, the common self-discharge problem of lead-acid batteries often troubles equipment users and maintenance personnel. Self-discharge not only leads to a decrease in the forklift's endurance, increases the charging frequency and operating costs, but in severe cases, it may also affect the normal use of the forklift and delay the operation progress. An in-depth exploration of the self-discharge problem of lead-acid batteries in forklifts and the discovery of practical solutions are of great significance for improving the efficiency of logistics operations and reducing operating costs.

1. Analysis of the Self-Discharge Principle of Forklift Lead-Acid Batteries

The self-discharge phenomenon of lead-acid batteries is essentially the spontaneous chemical reaction that occurs inside the battery when it is not connected to an external load, resulting in the loss of electrical energy. The core chemical reaction is based on the working principle of lead-acid batteries: inside the battery, lead dioxide on the positive plate and lead on the negative plate undergo an oxidation-reduction reaction under the action of sulfuric acid electrolyte, generating electrical energy. During the self-discharge process, even without an external current loop, the active substances inside the battery will still undergo side reactions with the electrolyte.

For example, lead on the negative plate will react with sulfuric acid to form lead sulfate and release electrons at the same time; On the positive plate, lead dioxide will also undergo some unexpected reduction reactions under the action of sulfuric acid. In addition, impurities inside the battery and impure components on the plates may also act as electrodes of the micro-battery, triggering local self-discharge reactions. These reactions continue, causing the battery power to gradually decrease and leading to the occurrence of self-discharge.

2. Key Factors Affecting Self-Discharge of Lead-Acid Batteries in Forklifts

(1) Temperature factor

Temperature has a significant influence on the self-discharge rate of lead-acid batteries. For every 10℃ increase in temperature, the self-discharge rate approximately doubles. Under high-temperature conditions, the chemical reactivity inside the battery increases, and the rate of side reactions accelerates, leading to intensified self-discharge. For instance, during the high-temperature period of summer, if forklifts are parked outdoors for a long time, the self-discharge rate of lead-acid batteries will significantly increase. In a low-temperature environment, although the self-discharge rate will decrease, the overall performance of the battery will also decline, such as reduced capacity and decreased charging and discharging efficiency.

(2) Purity and concentration of the electrolyte

Impurities in the electrolyte are one of the important causes of self-discharge. If the electrolyte contains metal impurities such as iron and copper, these impurities will form tiny primary cells inside the battery, accelerating the self-discharge process. In addition, the concentration of the electrolyte also affects self-discharge. When the concentration of the electrolyte is too high, it will accelerate the corrosion of the plates, thereby promoting self-discharge. Too low a concentration may lead to insufficient battery capacity. The appropriate electrolyte concentration should be strictly formulated in accordance with the requirements of the battery manufacturer.

(3) Quality and condition of battery plates

The purity of the plates and the manufacturing process directly affect the self-discharge condition of the battery. The impurities in the plates with low purity will participate in the self-discharge reaction. The sulfidation of the plates is also a common problem that leads to an increase in self-discharge. When a battery is in a state of long-term undercharge, undercharged or over-discharged, a layer of white and hard lead sulfate crystals will form on the surface of the plates, which is known as sulfation. After vulcanization, the active material of the plates decreases, self-discharge intensifies, and at the same time, it will also reduce the charging and discharging performance and service life of the battery.

(4) Usage and maintenance habits

The usage frequency and mode of forklifts have a significant impact on the self-discharge of lead-acid batteries. Frequent deep discharges and failure to charge in time will put the battery plates in a poor state and accelerate self-discharge. In addition, improper daily maintenance of the battery, such as not checking the electrolyte level regularly, not replenishing distilled water in time, and not performing regular equalization charging on the battery, will all aggravate the problem of battery self-discharge.

3. Detection Methods for Self-Discharge Problems of Lead-Acid Batteries in Forklifts

(1) Voltage measurement method

By measuring the open-circuit voltage of the battery, the self-discharge condition of the battery can be initially determined. After the battery is fully charged and has been left to stand for a period of time (usually 2 to 3 hours), use a high-precision voltmeter to measure the voltage of each individual cell. Regularly measuring and recording voltage changes can also help observe the development trend of battery self-discharge.

(2) Capacity testing method

Capacity testing is an effective method to detect the impact of self-discharge on battery performance. Use a professional battery capacity tester to conduct a complete discharge test on the battery and record the actual discharge capacity of the battery. Compare the actual capacity with the rated capacity of the battery. If the actual capacity is significantly lower than the rated capacity and other factors such as insufficient charging have been ruled out, it indicates that the battery has a relatively serious self-discharge problem, resulting in a decrease in available capacity.

(3) Internal resistance detection method

The change in the internal resistance of the battery can also reflect the self-discharge situation. As self-discharge intensifies, the chemical reactions inside the battery will lead to a reduction in the active material on the plates and changes in the concentration of the electrolyte, all of which will increase the internal resistance of the battery. Use an internal resistance tester to measure the internal resistance of the battery. If the internal resistance exceeds the normal range and is combined with other detection methods, it can be determined that the battery has a self-discharge problem. Generally speaking, the internal resistance of new batteries is relatively small. With the influence of usage and self-discharge, the internal resistance will gradually increase.

4. Solutions to the Self-Discharge Problem of Lead-Acid Batteries in Forklifts

(1) Optimize the usage environment

Temperature control: It is crucial to provide a suitable working and storage environment temperature for forklift lead-acid batteries. In high-temperature environments, forklifts can be parked in a cool and well-ventilated area to avoid direct sunlight. When necessary, sunshades, air conditioners and other equipment can be used to cool down the battery storage area. In low-temperature environments, batteries can be wrapped with insulation materials or equipped with heating devices to keep the battery temperature within a reasonable range (generally recommended to be between 5℃ and 35℃), which can reduce the self-discharge rate while ensuring the normal performance of the battery.

Humidity and dust prevention: Keep the battery storage environment dry and clean to prevent moist air and dust from entering the battery interior. A humid environment can easily cause the battery casing and plates to rust and corrode, accelerating self-discharge. Impurities in the dust may also enter the battery interior, triggering a self-discharge reaction. Regular cleaning and dehumidification of the battery storage area can effectively reduce the occurrence of self-discharge problems.

(2) Strictly control the quality of the electrolyte

Use high-purity electrolyte: Select electrolyte of reliable quality and high purity, and avoid using electrolyte containing impurities. When adding electrolyte, dedicated containers and tools should be used to prevent impurities from mixing in. At the same time, the concentration and liquid level of the electrolyte must be strictly controlled in accordance with the requirements of the battery manufacturer.

Regular inspection and maintenance: Regularly check the liquid level of the electrolyte. When the liquid level is below the minimum scale line, distilled water should be replenished in time. Note that only distilled water or dedicated lead-acid battery replenishment fluid can be added. Do not add tap water or other water containing impurities to avoid introducing new impurities and accelerating self-discharge. In addition, the density and concentration of the electrolyte should be regularly tested, and adjustments should be made based on the test results to ensure that the electrolyte is in the best condition.

(3) Improve the quality and maintenance level of the plates

When purchasing lead-acid batteries, give priority to products with reliable quality and high plate purity. High-quality plates not only have a low self-discharge rate, but also a long service life and stable charging and discharging performance. You can choose the right battery product by checking the product certification, learning about the manufacturer's production process and reputation, etc.

Prevention and treatment of plate sulfation: To prevent plate sulfation, it is necessary to avoid the battery being in a state of low charge for a long time. After each use, it should be charged in time and ensure sufficient charging time. For batteries that have already shown signs of sulfation, methods such as long-term charging with a small current and pulse repair can be adopted for treatment. Long-term charging with a small current can gradually dissolve the lead sulfate crystals and restore the activity of the plates. Pulse repair utilizes high-frequency pulse current to break up lead sulfate crystals, achieving the purpose of repair.

(4) Standardize the use and maintenance operations

Reasonable charging and discharging: Follow the correct charging and discharging principles to avoid over-discharging and deep discharging. Generally speaking, when the battery power remains at 20% to 30%, it should be charged. During the charging process, use a charger that matches the battery specifications and operate strictly in accordance with the charger's instructions to avoid overcharging or undercharging. In addition, regularly perform equalization charging on the battery, usually once every 2 to 3 weeks, which can make the voltage and capacity of each cell of the battery tend to be consistent and reduce the differences in self-discharge.

Regular maintenance and care: Establish a complete battery maintenance and care system and conduct regular inspections and maintenance of batteries. In addition to checking the electrolyte level and concentration, it is also necessary to inspect whether the battery connection wires are loose or oxidized, and whether the battery casing is damaged or leaking. Clean the dust and electrolyte residue on the battery surface in time to keep the battery surface clean and dry. Meanwhile, regular performance tests should be conducted on the battery, such as voltage measurement, capacity testing, and internal resistance detection, to promptly identify and address issues like self-discharge.

5. Conclusion

The self-discharge issue of lead-acid batteries in forklifts is a comprehensive challenge, involving multiple aspects such as the battery's principle, usage environment, electrolyte quality, plate condition, and usage and maintenance. By deeply understanding the principle of self-discharge, accurately grasping the key factors affecting self-discharge, applying scientific detection methods, adopting targeted solution strategies, and continuously optimizing and improving the solutions in combination with actual cases, the self-discharge rate of lead-acid batteries can be effectively reduced, the performance and service life of the batteries can be enhanced, thereby improving the working efficiency of forklifts. Reduce the operating costs of logistics and warehousing enterprises. In practical applications, enterprises should attach great importance to the self-discharge issue of batteries, strengthen daily management and maintenance, and ensure the stable operation of forklift equipment.