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Introduction

In the fields of modern logistics and industrial production, forklifts, as key material handling equipment, play a crucial role in the entire production process in terms of their operational efficiency and stability. As the main power source of forklifts, the performance of lead-acid batteries directly affects the working performance of forklifts. Forklift lead-acid batteries of different brands, models and usage environments have significant performance differences in terms of capacity, lifespan and charging and discharging efficiency. A thorough understanding of these performance differences is of great significance for enterprises to rationally select and use lead-acid batteries for forklifts, reduce operating costs and improve production efficiency.

Performance indicators of lead-acid batteries for forklifts

Capacity

Rated capacity: Rated capacity refers to the amount of electricity that a battery can release under specified discharge conditions, usually measured in ampere-hours (Ah). Rated capacity is an important indicator for measuring a battery's energy storage capacity. The larger the capacity, the longer and more distance a forklift can usually run after a single charge. For forklifts that frequently perform long-distance handling operations, choosing large-capacity batteries can effectively reduce the number of charging times and improve work efficiency.

Actual capacity: The actual capacity is influenced by various factors, such as the size of the discharge current, ambient temperature, and the battery's service life. When the discharge current increases, the actual capacity of the battery will decrease. This is because high current discharge can lead to incomplete chemical reactions inside the battery, and some active substances cannot fully participate in the reactions. The impact of ambient temperature on actual capacity is also quite significant. In a low-temperature environment, the chemical reaction rate of the battery slows down, the internal resistance increases, and the actual capacity will decrease significantly. Generally, for every 1℃ drop in temperature, the battery capacity decreases by approximately 0.8% to 1%. As the battery's service life increases, the active substances on the plates gradually fall off, the internal resistance of the battery increases, and the actual capacity will also gradually decrease.

Cycle life

Cycle life refers to the number of charge and discharge cycles that a battery can achieve a specified capacity retention rate under certain charge and discharge conditions. Generally speaking, the cycle life of high-quality lead-acid batteries for forklifts can reach 1,500 times. Cycle life reflects the durability of a battery. The longer the cycle life, the longer the effective working time that the battery can provide during its service life, and the lower the frequency of battery replacement for enterprises, thereby reducing the long-term usage cost of the equipment. However, in actual use, the cycle life of a battery is affected by factors such as the depth of charging and discharging, charging methods, and the usage environment. Frequent deep discharges will accelerate the sulfation and aging of battery plates, significantly shortening the cycle life. Unreasonable charging methods, such as overcharging and undercharging, can also cause damage to the battery and reduce its cycle life.

Charge and discharge efficiency

Charging efficiency: Charging efficiency refers to the ratio of the stored electrical energy to the input electrical energy during the charging process of a battery. The charging efficiency of lead-acid batteries is generally between 75% and 90%. The charging efficiency is affected by factors such as the performance of the charger, charging current, and battery temperature. An efficient charger can intelligently adjust the charging current and voltage according to the battery's status, reducing energy loss during the charging process and improving charging efficiency. When the charging current is too large, a considerable amount of heat will be generated inside the battery, resulting in a decrease in charging efficiency and possibly causing damage to the battery. Excessively high or low battery temperatures can also affect charging efficiency. Generally, the optimal charging temperature for lead-acid batteries is around 25℃.

Discharge efficiency: Discharge efficiency refers to the ratio of the electrical energy output by a battery during the discharge process to the electrical energy stored in the battery. The discharge efficiency is mainly related to the magnitude of the discharge current and the internal resistance of the battery. The greater the discharge current is, the greater the voltage drop across the battery's internal resistance will be, resulting in a decrease in output voltage and a decline in discharge efficiency. The internal resistance of the battery increases with the increase of usage time, which also leads to a gradual decrease in the discharge efficiency. High discharge efficiency means that batteries can more effectively convert stored chemical energy into electrical energy to power forklifts and reduce energy waste.

Self-discharge rate

Self-discharge rate refers to the rate at which a battery loses electricity due to spontaneous chemical reactions inside when it is in an open-circuit state. The self-discharge rate of lead-acid batteries is relatively high, generally ranging from 2% to 5% per month. Self-discharge can cause the battery's power to drop after being idle for a long time, affecting the normal use of forklifts. The main causes of self-discharge include the presence of impurities inside the battery, the unevenness of the plate material, and the impurity of the electrolyte, etc. To reduce the impact of self-discharge, when forklifts are not in use for a long time, the battery should be replenished regularly to keep the battery power at a high level.

Factors affecting the performance differences of lead-acid batteries in forklifts

Battery materials and manufacturing processes

Plate material: The plates are the core components of lead-acid batteries, and the quality of their materials plays a crucial role in the battery's performance. High-quality plates are made of high-purity lead alloys, such as 1# electrolytic lead, which has a low impurity content and can effectively reduce the self-discharge rate, improve the charging and discharging performance and cycle life of the battery. The positive plate grid is mostly formed by die-casting with enhanced multi-element low-antimony corrosion-resistant alloy. This alloy features low internal resistance and high-rate discharge performance, which can reduce sulfation and corrosion of the plates and extend the battery's service life. Some low-quality plates may be made of recycled lead or low-purity lead alloys, which contain more impurities. This can easily lead to plate corrosion and the shedding of active substances, thereby reducing battery performance.

Electrolyte: The electrolyte is generally a sulfuric acid solution, and its concentration and purity have a significant impact on battery performance. An appropriate concentration of sulfuric acid can ensure the smooth progress of chemical reactions inside the battery, and enhance the battery's capacity and charging and discharging efficiency. The electrolyte is of high purity and free of impurities, which can reduce the self-discharge and corrosion phenomena inside the battery. If the concentration of the electrolyte is too high, it may accelerate the corrosion of the plates. If the concentration is too low, it will reduce the capacity of the battery. During the battery's usage, due to the evaporation of water and the consumption of chemical reactions, the concentration of the electrolyte will change, and it is necessary to check and adjust it regularly.

Manufacturing process: Advanced manufacturing processes can ensure the quality and consistency of each component of the battery. During the manufacturing process of the plates, the adoption of precise casting plate technology and paste coating technology can ensure the uniform distribution of active substances on the plates, thereby enhancing their activity and stability. During the battery assembly process, strictly controlling the assembly accuracy and ensuring uniform spacing between the plates and reliable connection can reduce the internal resistance of the battery and improve its charging and discharging performance. Meanwhile, a good sealing process can prevent the leakage of electrolyte and the entry of external impurities into the battery interior, ensuring the normal service life of the battery.

Usage environment

Temperature: Temperature has a significant impact on the performance of lead-acid batteries in forklifts. In high-temperature environments, the chemical reaction rate inside the battery accelerates, and the evaporation of the electrolyte intensifies, which can easily lead to water loss and sulfation of the plates, thereby shortening the battery's lifespan. At the same time, high temperatures will also increase the self-discharge rate of batteries and accelerate the loss of power. In low-temperature environments, the internal resistance of batteries increases, the rate of chemical reactions slows down, and both battery capacity and charge and discharge efficiency decrease. As mentioned earlier, for every 1℃ drop in temperature, battery capacity approximately decreases by 0.8% to 1%. Therefore, to ensure the stability of battery performance, the operating environment temperature of the forklift should be controlled within an appropriate range as much as possible. For forklifts working in high or low temperature environments, corresponding temperature control measures can be taken, such as installing battery cooling or heating devices.

Humidity: Humidity also has a certain impact on battery performance. In a high-humidity environment, the battery casing and terminals are prone to corrosion, resulting in increased contact resistance and affecting the battery's charging and discharging performance. Meanwhile, moisture may seep into the battery, dilute the electrolyte, change its concentration, and thereby affect the chemical reactions of the battery. Therefore, the working environment of the battery should be kept dry to avoid the battery being in a high-humidity environment for a long time.

Vibration and shock: During operation, forklifts are inevitably subject to vibration and shock, which may cause the internal plates of the battery to loosen and the connection parts to break, thereby affecting the performance and lifespan of the battery. To reduce the impact of vibration and shock on the battery, shock-absorbing pads and other buffering devices can be used during battery installation to ensure a firm installation and minimize shaking during operation.

Charging and discharging mode

Charging methods: Different charging methods have a significant impact on battery performance. Common charging methods include constant current charging, constant voltage charging and pulse charging, etc. Constant current charging refers to maintaining a constant charging current during the charging process. This method has a relatively slow charging speed, but it can better control the battery's charging state and prevent overcharging. Constant voltage charging keeps the charging voltage constant during the charging process. As the charging progresses, the current gradually decreases. This charging method is relatively fast, but if not properly controlled, it can easily lead to overcharging of the battery. Pulse charging is a new type of charging method developed in recent years. By intermittently applying pulse current, it can effectively reduce the sulfation of battery plates, improve the charging acceptance capacity and lifespan of the battery. By adopting an intelligent charging management system, the charging method and parameters can be automatically adjusted according to the real-time status of the battery to achieve the best charging effect and extend the battery life.

Depth of discharge: Depth of discharge refers to the percentage of electricity discharged by a battery during the discharge process to its rated capacity. Frequent deep discharges will accelerate the sulfation and aging of battery plates, shortening the battery's lifespan. It is generally recommended that the discharge depth of lead-acid batteries in forklifts be controlled between 50% and 80% to avoid excessive discharge. When the battery power drops below a certain level, it should be charged in time to protect the battery performance. In practical use, a battery power monitoring device can be installed to monitor the battery power in real time and remind the operator to charge it in time.

The influence of performance differences of forklift lead-acid batteries on applications

The impact on the operational efficiency of forklifts

The impact of capacity differences: Large-capacity lead-acid batteries for forklifts can provide longer power support for forklifts, reduce the frequency of charging, and increase the continuous operation time of forklifts. In high-intensity operation sites such as large logistics warehouses or ports, forklifts need to continuously move goods for long periods of time. Large-capacity batteries can ensure the efficient operation of forklifts and avoid operation interruptions caused by frequent charging. Forklifts with small-capacity batteries, on the other hand, need to be charged more frequently, which not only delays operation time but may also affect the smoothness of the entire logistics process.

The impact of differences in charging and discharging efficiency: Batteries with high charging and discharging efficiency can charge faster and discharge more effectively, providing sufficient power for forklifts. Fast-charging batteries can replenish their power in a short time, enabling forklifts to quickly engage in the next round of operations and enhancing their operational efficiency. Batteries with high discharge efficiency can output more stable voltage and current during the discharge process, ensuring the power performance of forklifts during operation and avoiding problems such as reduced operating speed and weakened lifting capacity of forklifts caused by insufficient battery power.

The impact on the service life of forklifts

The impact of cycle life differences: Forklift lead-acid batteries with long cycle life can withstand more charge and discharge cycles, providing more stable power support for forklifts throughout their service life. This means that enterprises do not need to frequently replace batteries, reducing the downtime and costs caused by battery replacement. For enterprises that use forklifts for a long time, choosing batteries with a long cycle life can effectively reduce the total cost of ownership of the equipment. On the contrary, batteries with short cycle life may need to be replaced frequently, which not only increases the procurement cost but also may affect the normal use of forklifts due to untimely battery replacement, reducing the production efficiency of enterprises.

The impact of differences in self-discharge rate: Batteries with a low self-discharge rate can maintain a high level of power even after being idle for a long time. When the forklift is used again, it does not need to spend a lot of time charging and can be quickly put into operation. This is particularly important for some forklifts that are not frequently used. Batteries with a high self-discharge rate may experience a significant drop in power if left idle for a long time, and may even fail to meet the starting requirements of forklifts. Frequent supplementary charging is required, which increases maintenance costs and causes inconvenience in use.

Conclusion

Forklift lead-acid batteries have significant differences in performance aspects such as capacity, cycle life, charge and discharge efficiency, and self-discharge rate. These differences are influenced by various factors including battery materials and manufacturing processes, usage environments, and charge and discharge methods. Different types of lead-acid batteries for forklifts, such as the common flooded type, maintenance-free type and gel type, each have their own distinct performance characteristics. These performance differences have a significant impact on the operational efficiency, service life and operating costs of forklifts. When enterprises choose lead-acid batteries for forklifts, they should fully consider their own operation requirements, usage environment and cost budget and other factors, comprehensively evaluate the performance differences of different batteries, and select the most suitable battery to ensure the efficient and stable operation of forklifts, reduce operating costs and improve the economic benefits of enterprises. At the same time, during the battery's usage, attention should be paid to reasonable charging and discharging methods as well as maintenance and care to extend the battery's service life and fully leverage its performance advantages. ​