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1. Introduction

In the fields of modern logistics and industrial production, forklifts, as key material handling equipment, their efficient and stable operation is crucial for enhancing operational efficiency and ensuring the smoothness of production processes. Lead-acid batteries, as one of the mainstream power sources for forklifts, occupy an important position due to their advantages such as cost-effectiveness and technological maturity. However, due to the chemical energy contained inside and the electrochemical reactions involved in its working process, safety issues cannot be ignored. Once a safety accident occurs, it will not only cause equipment damage and production halt, but also pose a serious threat to the lives and safety of operators as well as the surrounding environment. Therefore, an in-depth exploration of the safety design and safeguard measures for lead-acid batteries in forklifts holds extremely significant practical significance. This is not only a powerful protection for personnel and property safety but also an inevitable requirement for promoting the sustainable development of the industry.

2. Working Principle and Potential Safety Risks of Lead-Acid Batteries in Forklifts

2.1 Brief Description of Working Principle

The operation of lead-acid batteries is based on electrochemical principles and mainly consists of positive and negative plates, electrolyte, separators and battery casings, etc. During the discharge process, lead dioxide at the positive electrode and lead at the negative electrode respectively undergo chemical reactions with sulfuric acid in the electrolyte, converting chemical energy into electrical energy to provide power for the forklift's motor. When charging, the process is the opposite. Electrical energy is converted into chemical energy and stored.

2.2 Potential Safety Risk Analysis

1. ** Electrolyte leakage Risk ** : The electrolyte of lead-acid batteries is a highly corrosive sulfuric acid solution. In the daily operation of forklifts, it is inevitable to encounter jolts, vibrations and even collisions. If the battery casing develops cracks due to long-term vibration or is damaged after an accidental impact, the electrolyte is highly likely to leak. Once leaked, sulfuric acid will cause severe corrosion to the metal parts of forklifts, shortening the service life of the equipment. Moreover, if it leaks to the ground, it will pollute the surrounding environment. If it comes into contact with people's skin, eyes, etc., it will cause serious chemical burns.

2. ** Gas explosion risk ** : During the charging and discharging process of lead-acid batteries, hydrogen and oxygen are produced through side reactions. Especially in the later stage of charging, water is electrolyzed and the amount of hydrogen gas released increases significantly. When the charging environment is poorly ventilated, hydrogen will accumulate in the local space and mix with air to form a flammable mixture. The explosion limit range of hydrogen is relatively wide, ranging from 4.0% to 75.6%. Once exposed to ignition sources such as open flames or electric sparks, it is highly likely to cause an explosion accident, dealing a devastating blow to personnel and equipment.

3. ** Overheating and Thermal Runaway Risk ** : When forklifts operate under high load for a long time, or when there are abnormal conditions such as internal short circuits or overcharging in the battery, the chemical reactions inside the battery will intensify, generating a large amount of heat. If the battery cooling system is not designed properly and cannot dissipate heat in time, the battery temperature will continue to rise. When the temperature exceeds a certain threshold, it may trigger thermal runaway, causing a sharp deterioration in battery performance and even serious consequences such as fire and combustion.

4. ** Electrical Safety Risk ** : Lead-acid batteries output a relatively high voltage during operation. If the battery connection lines are loose or the insulation layer ages and gets damaged, it can lead to leakage. When operators come into contact with forklifts, they may suffer electric shock, which endangers their lives. In addition, poor contact at electrical connection points may also generate electric sparks, which can serve as a potential ignition source for flammable gases such as hydrogen.

3. Safety Design Strategy

3.1 Optimization of battery structure design

1. ** Selection of high-strength shell materials ** : To effectively resist the vibration and impact during forklift operation, the battery shell should be made of high-strength and impact-resistant engineering plastic materials, such as alloy materials of polycarbonate and acrylonitrile butadiene-styrene copolymer. This material not only has excellent mechanical strength, capable of withstanding a certain degree of external impact without cracking, but also possesses good chemical stability and strong corrosion resistance to sulfuric acid electrolyte, which can significantly reduce the risk of electrolyte leakage.

2. ** Sealing and Leak-proof Design ** : Advanced sealing techniques such as hot melt welding and rubber sealing rings are adopted to ensure that all components of the battery casing are tightly connected without any leakage gaps. At the connection between the battery cover and the shell, multiple sealing structures are set up, and the sealing performance is strictly tested. For example, a helium mass spectrometer leak detector is used for air tightness testing to ensure that the electrolyte will not seep out even under extreme vibration conditions. In addition, some high-end lead-acid batteries are equipped with anti-leakage trays inside. Once a small amount of electrolyte leaks, it can be temporarily stored to prevent it from flowing out and causing harm.

3. ** Internal Structure reinforcement ** : Reinforcement design is carried out for components such as plates and separators inside the battery. Adopting an anti-vibration plate fixing structure, such as using high-strength plastic frames to firmly fix the plates, it prevents the plates from displacing or deforming during vibration, avoids short circuits between the plates, thereby ensuring the stable progress of the electrochemical reaction inside the battery and reducing the safety risks caused by internal structure damage.

3.2 Electrical Safety Design

1. Integration of Overcharge, overdischarge and short-circuit protection circuits: Integrate overcharge, overdischarge and short-circuit protection circuits in the battery management system. When the battery charging voltage reaches the preset overcharge protection threshold, the protection circuit automatically cuts off the charging circuit to prevent the battery from overheating, losing water or even exploding due to overcharging. When the battery discharges to the over-discharge protection voltage, the discharge circuit should be disconnected in time to prevent excessive discharge of the battery, which may cause sulfation of the plates, affecting the battery's lifespan and performance. At the same time, it can also prevent potential safety hazards caused by excessive discharge. When a short circuit is detected in the internal or external circuits of the battery, the protection circuit acts promptly, cutting off the current at a millisecond speed to prevent excessive short-circuit current from causing a fire or damaging the battery.

2. ** Equipped with leakage protection device ** : To prevent personnel from being harmed by battery leakage, a leakage protection device is installed in the battery system. The leakage protection device monitors the leakage current of the battery circuit in real time. Once it detects that the leakage current exceeds the safety threshold, it immediately cuts off the power supply to protect the safety of the operator. Meanwhile, the grounding system of the battery is optimized to ensure reliable grounding, quickly conducting leakage current into the ground and further reducing the risk of electric shock.

3. ** Electrical Connection Reliability Design ** : High-quality electrical connection components, such as tin-plated copper terminals and high-strength cable joints, are adopted to ensure the stable and reliable electrical connection of the battery connection lines. Special treatment should be carried out on the joint area, such as applying conductive paste to reduce contact resistance and decrease the heat generated by excessive contact resistance. Lay out the connecting lines reasonably to avoid crossing and entanglement of the lines, and prevent the insulation layer from being damaged due to friction, which may cause electrical faults and safety accidents.

3.3 Design of Thermal Management System

1. ** Heat Dissipation Structure Design ** : Heat dissipation fins are designed on the battery casing to increase the heat dissipation area and accelerate the speed at which the heat inside the battery dissipates to the surrounding environment. For lead-acid battery packs of large forklifts, air cooling or liquid cooling methods can be adopted for heat dissipation. The air-cooling system forces the air to flow through fans installed around the battery pack, taking away the heat generated by the battery. The liquid cooling system utilizes the coolant to circulate in the cooling pipes inside the battery, efficiently absorbing and removing heat. When designing the heat dissipation system, the actual working environment of the forklift and the heat generation characteristics of the battery should be fully considered. The heat dissipation method and parameters should be reasonably selected to ensure that the battery can remain within the appropriate working temperature range under various working conditions.

4. Safety Assurance Measures

4.1 Production and Manufacturing quality control

1. ** Raw Material Quality Control ** : Starting from the source, strictly screen and quality inspect the raw materials required for the production of lead-acid batteries. Ensure that the lead plates are made of high-purity lead alloy and the impurity content is controlled at an extremely low level to guarantee the stable electrochemical performance of the plates and reduce the risk of self-discharge and short circuit. The purity of sulfuric acid in the electrolyte should comply with national standards, and its concentration should be precisely adjusted to ensure the charging and discharging performance and service life of the battery. Comprehensive tests are conducted on the physical properties and chemical stability of materials such as partitions and shells. Only raw materials that meet the quality requirements can be put into production.

2. ** Standardization of Production Processes ** : Establish strict and standardized production process flows and precisely control each production procedure. During the manufacturing process of the plates, parameters such as the thickness of the paste, curing temperature and time are strictly controlled to ensure the uniform distribution of the active substances on the plates and improve the consistency and reliability of the plates. During the battery assembly stage, standardize the welding process, sealing process and other operation procedures to ensure that the internal connection of the battery is firm and the sealing is good. Establish a complete quality traceability system for the production process, record the key parameters and operators of each production link. Once a quality problem occurs, the source of the problem can be quickly traced and rectification measures can be taken.

3. ** Strict factory inspection ** : Before batteries leave the factory, comprehensive and strict performance and safety tests are conducted. In addition to the regular capacity tests and charge and discharge cycle life tests, safety performance tests are also focused on, such as electrolyte leakage tests, gas emission tests, overcharge and overdischarge protection function tests, and thermal stability tests, etc. Only batteries that have passed all the inspection items and all indicators meet the standard requirements can be allowed to leave the factory, ensuring that every lead-acid battery entering the market has reliable safety.

4.2 Installation and Maintenance Specifications

1. ** Professional Installation Guidance and training ** : During the installation of lead-acid batteries in forklifts, professional technicians should operate in accordance with the battery installation manual. Before installation, check the battery installation position of the forklift to ensure that the installation platform is flat, firm, free of debris and sharp objects, and avoid additional external force squeezing or damage to the battery after installation. Provide professional training to the installers to familiarize them with the battery installation process, precautions and electrical connection requirements, ensuring that the installation process is standardized and correct, and preventing safety issues caused by improper installation.

2. Establishment of Regular maintenance and care system: Develop a detailed regular maintenance and care plan for lead-acid batteries, clearly defining the maintenance cycle and content. Regularly inspect the appearance of the battery to see if the casing is damaged and if there are any signs of electrolyte leakage. Check the electrolyte level and density of the battery, and replenish distilled water in time or adjust the density of the electrolyte. Clean the positive and negative terminals of the battery to prevent oxidation and corrosion and ensure good electrical connection. Check whether the connection lines of the battery are loose and whether the insulation layer is damaged. At the same time, regularly conduct charge and discharge tests on the battery to assess its performance status, promptly identify potential problems and handle them.

3. ** Safety Protection Measures for Maintenance Personnel ** : When conducting battery maintenance operations, maintenance personnel must strictly wear personal safety protection equipment, such as acid-resistant gloves, protective glasses, and protective aprons, to prevent electrolyte from splashing onto the skin and eyes and causing injury. When handling batteries, appropriate handling tools such as forklifts and pallet trucks should be used, and it is necessary to ensure a smooth handling process to prevent the batteries from falling. When performing electrical connection or detection operations, disconnect the battery power first to prevent electric shock accidents.

5. Conclusion

The safety design and guarantee of lead-acid batteries for forklifts is a systematic project, covering multiple links from battery design and manufacturing, installation and use, maintenance management to personnel training. By optimizing the battery structure design and strengthening the design of electrical safety and thermal management systems, the safety performance of the battery is enhanced from the source. By means of strict production and manufacturing quality control, standardized installation and maintenance procedures, as well as comprehensive personnel training and safety awareness enhancement, a comprehensive and multi-level safety guarantee system has been established, effectively reducing the potential safety risks of lead-acid batteries in forklift applications. With the continuous progress and innovation of technology, in the future, we should continue to pay attention to the application of new materials and new technologies in the safety field of lead-acid batteries, further improve safety design and safeguard measures, provide solid and reliable power support for the safe and efficient operation of forklifts, and promote the sustainable development of the logistics and industrial production industries.