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Introduction

In modern logistics and industrial production, forklifts, as important material handling equipment, the stability and safety of their operation are of vital importance. Forklift lead-acid batteries, as the power source of forklifts, their performance and safety are directly related to the overall operation status of forklifts. However, lead-acid batteries face many risks during use, among which the short-circuit problem is particularly prominent. Short circuits not only affect the performance and lifespan of batteries, but may also cause serious safety accidents such as fires and explosions, posing a huge threat to people and property. Therefore, in-depth research on the anti-short-circuit design of forklift lead-acid batteries is of extremely important practical significance for ensuring their safe use.

1. Hazards of Short Circuit in Forklift Lead-Acid Batteries

(1) Battery performance and lifespan are impaired

When a short circuit occurs in the lead-acid battery of a forklift, an abnormally large current path will form inside the battery. According to Ohm's Law, when a short circuit occurs, the resistance drops sharply and the current will increase significantly instantly. This will cause a large amount of heat to be generated inside the battery, causing the battery temperature to rise rapidly. High temperatures will accelerate the rate of chemical reactions inside the battery, causing excessive loss of active substances and deformation of the plates. For instance, the lead dioxide on the positive plate may fall off due to high temperature, and the spongy lead structure on the negative plate will also be damaged, thereby seriously reducing the battery's capacity and charging and discharging performance. If a battery remains in a short-circuit state for a long time or experiences frequent short circuits, its lifespan will be significantly shortened. A battery that could have been used normally for several years may need to be replaced in a short period of time, increasing the cost of use.

(2) The risk of safety accidents has increased

The high temperature and large current caused by a short circuit may cause the electrolyte inside the battery to heat up rapidly and boil, generating a large amount of flammable gases such as hydrogen and oxygen. These gases accumulate in the limited battery space. Once they come into contact with ignition sources such as fire sources or static electricity, they are highly likely to cause explosions and fires. In places such as warehouses and factories where forklifts operate, there are often a large number of flammable materials and human activities. Fire and explosion accidents caused by battery short circuits may lead to rapid spread of the fire, resulting in serious casualties and huge property losses. In addition, short circuits may also cause the battery casing to crack and the electrolyte to leak. Electrolyte is usually highly acidic and can cause corrosion to surrounding equipment, the ground, etc. At the same time, it may also cause burns to the skin and eyes of people who come into contact with it, bringing serious occupational health hazards.

2. Common Causes of Short Circuit in Forklift Lead-Acid Batteries

(1) Physical damage causes a short circuit

External impact and compression: During the daily operation of forklifts, the battery may be subject to external impact or compression due to improper operation, collision with shelves or other obstacles, etc. For instance, when a forklift is traveling in a narrow passage, a violent collision between the battery area and the corner of the shelf may cause the battery casing to crack, the internal plates to deform, and the positive and negative plates to come into contact with each other, thereby triggering a short circuit. In addition, during the handling and installation of batteries, if the correct hoisting and fixing methods are not adopted, it is also easy for the batteries to be subjected to improper external forces, causing damage to the internal structure and laying the groundwork for short circuits.

Battery aging and wear: As the usage time increases, the lead-acid batteries of forklifts will gradually age. The plates, separators and other components inside the battery will wear out and corrode due to long-term charge and discharge cycles. For instance, the active substances on the surface of the plates will gradually fall off, and the insulation performance of the separator will decline. When too much of the fallen active material accumulates at the bottom of the battery, it may form a conductive path between the positive and negative plates, causing a short circuit. Meanwhile, aged separators may suffer from damage, perforation and other conditions, which cannot effectively prevent the electron conduction between the positive and negative plates, thereby causing short circuit problems.

(2) Improper electrical connection causes a short circuit

Wiring error: When installing, maintaining or replacing the connection wires of the battery, if the operator is not familiar with the electrical principles and operating procedures, wiring errors may occur. For instance, reversing the positive and negative terminals or failing to ensure a secure connection during the connection process can lead to a loose connection. When a large current passes through the loosely connected part, it will generate high temperatures, which may erode the terminals and connecting wires, and then cause a short circuit. In addition, when battery connection wires of different specifications are mixed, the wire diameter may be too small to withstand the normal working current, causing the wires to overheat and short circuit.

Insulation failure: The connection wires, plugs and other parts of the battery need good insulation performance to prevent leakage and short circuit. However, in practical use, insulating materials may age and break due to long-term exposure to harsh environments such as high temperatures, humidity, and corrosive gases. For instance, in some food processing plants or chemical enterprises, there is a large amount of water vapor and corrosive chemicals in the forklift operation environment, which will accelerate the aging of insulating materials. When the insulating material fails, the metal conductor part of the wire may come into contact with the battery casing or other metal components, forming a short-circuit loop.

(3) Short circuit caused by electrolyte problems

Electrolyte drying up: During the operation of forklift lead-acid batteries, the moisture in the electrolyte will gradually evaporate. If distilled water is not replenished in time, the electrolyte level will drop, causing part of the plates to be exposed above the liquid surface. The plates exposed above the liquid surface are prone to oxidation in the air, and the generated oxides have poor conductivity, which will affect the performance of the battery. At the same time, the resistance between the plates will increase. To maintain normal current output, the current density inside the battery will increase, which may cause local overheating of the plates, leading to plate deformation and subsequently causing a short circuit.

Electrolyte impurity contamination: If conductive substances such as metal impurities are accidentally mixed in during the process of adding electrolyte or maintaining the battery, these impurities may form conductive paths in the electrolyte, connecting the positive and negative plates, thereby causing a short circuit. For instance, when using tools to clean the surface of a battery, if metal debris from the tools accidentally falls into the electrolyte, this situation may occur. In addition, after long-term use, some internal components of the battery may corrode, and the metal ions produced may also contaminate the electrolyte, increasing the risk of short circuits.

3. Key Points for Short-circuit Prevention Design of Lead-Acid Batteries in Forklifts

(1) Physical protection design

Sturdy battery casing: The battery casing is made of high-strength and impact-resistant materials, such as high-quality engineering plastics or metal materials. For instance, some forklift lead-acid batteries use thickened polypropylene casings. This material has excellent mechanical properties and chemical stability, effectively resisting external impacts and compressions, and preventing the battery casing from cracking and causing internal short circuits. Meanwhile, the design of the casing should comply with ergonomics and the installation space requirements of forklifts, facilitating installation and maintenance.

Internal structure reinforcement: Inside the battery, the plates and separators should be reasonably fixed and supported to prevent the plates from shifting or colliding due to vibration and shaking during transportation and use. For example, a special frame structure is adopted to tightly fix the plates and separators to ensure the stability of their relative positions. In addition, a protective coating can be applied to the surface of the plates to enhance their anti-deformation ability and corrosion resistance, and reduce the risk of short circuits caused by plate deformation.

(2) Optimized design of electrical connections

Correct wiring design: During the battery design stage, clearly specify the wiring method and the identification of terminals to ensure that operators can connect correctly. The wiring plug adopts an anti-misinsertion design to avoid short circuits caused by connection instead. Meanwhile, special treatment is carried out on the terminal posts and connecting wires to enhance the reliability and conductivity of the connection. For instance, using tin-plated terminal posts and copper connecting wires can reduce contact resistance, decrease the possibility of heat generation and short circuits.

Enhanced insulation measures: For the electrical connection parts of the battery, such as terminals, plugs, wires, etc., high-quality insulating materials should be used to wrap and protect them. For instance, use silicone rubber insulating sleeves that are resistant to high temperatures, moisture and have excellent insulation performance to protect the terminal posts, and use double-layer insulated wires as connecting wires. In addition, insulating partitions are set inside the battery casing to isolate the electrical connection parts from other battery components, further enhancing the insulation performance and preventing leakage and short circuits.

(3) Electrolyte Management Design

Automatic liquid replenishment system: To prevent short circuits caused by the drying up of the electrolyte, some advanced forklift lead-acid batteries are equipped with an automatic liquid replenishment system. This system is capable of monitoring the electrolyte level in real time. When the level is lower than the set value, it automatically replenishes distilled water. For instance, by using a liquid level sensor to sense changes in the liquid level, when the liquid level drops to a certain extent, the sensor triggers a signal to control the liquid replenishment device to inject an appropriate amount of distilled water into the battery, ensuring that the electrolyte always remains at an appropriate liquid level and maintaining the normal performance of the battery.

Electrolyte purification device: To reduce short circuits caused by electrolyte impurity contamination, an electrolyte purification device can be installed inside the battery or in an external connection device. This device is capable of filtering metal impurities and other contaminants in the electrolyte to maintain its purity. For instance, technologies such as microporous filtration membranes or ion exchange resins are adopted to circulate and filter the electrolyte, removing impurity ions and reducing the risk of short circuits.

(4) Short-circuit protection circuit design

Overcurrent protection circuit: An overcurrent protection circuit is set up in the charging and discharging circuit of the battery. When the current is detected to exceed the set safety threshold, the circuit is immediately cut off to prevent damage to the battery caused by excessive short-circuit current. For instance, a current sensor is used to monitor the current magnitude in the circuit in real time. Once the current abnormally increases, the relay in the overcurrent protection circuit will act promptly to disconnect the circuit, preventing the short-circuit current from continuously causing harm to the battery.

Leakage detection and protection: Install leakage detection devices to monitor the leakage situation of the battery system in real time. When the leakage current is detected to exceed the allowable value, an alarm should be issued promptly and protective measures taken, such as cutting off the power supply. For instance, a leakage current sensor is used to detect the leakage current between the battery casing and the ground. Once a leakage is detected, the leakage protection device acts promptly to prevent electric shock and short circuit accidents.

4. Conclusion

The short-circuit problem of lead-acid batteries in forklifts poses a serious threat to the safe operation and service life of forklifts. By thoroughly understanding the hazards of short circuits and their common causes, and adopting targeted design points for preventing short circuits, such as physical protection design, electrical connection optimization design, electrolyte management design, and short-circuit protection circuit design, the risk of short circuits can be effectively reduced, ensuring the safe use of lead-acid batteries in forklifts. In practical applications, all enterprises and users should attach great importance to the anti-short-circuit measures for forklift lead-acid batteries, choose products with good anti-short-circuit design, and strengthen daily maintenance and management. Meanwhile, relevant industries and standard-setting departments should also constantly improve the design, manufacturing and usage standards of forklift lead-acid batteries, promote technological innovation, further enhance the safety and reliability of forklift lead-acid batteries, and provide a strong guarantee for the safe development of modern logistics and industrial production.