In various industrial scenarios, cranes, as key material handling equipment, undertake heavy lifting tasks. And crane batteries, as the "energy heart" of electric cranes, their performance directly affects the working efficiency, stability and service life of cranes.

I. Types and Characteristics of Crane Batteries

(1) Lead-acid Batteries - Traditional Mainstay

Lead-acid batteries have a long history of application in the crane field and are currently the most common type. It uses lead and its oxides as electrodes and sulfuric acid solution as the electrolyte. The outstanding advantage of this type of battery lies in its relatively low cost and mature technology, with high cost performance. For example, common 12V lead-acid batteries are widely used in small to medium-sized cranes. It can provide a large starting current to meet the instantaneous high-power demand of cranes. For small cranes used to lift building materials at construction sites, lead-acid batteries can ensure a strong power output during each lift. Moreover, the raw materials of lead-acid batteries are widely available and the production process is mature, ensuring a stable supply in the market. However, lead-acid batteries also have some obvious disadvantages. Their energy density is relatively low, which means that under the same power, the battery has a large volume and weight, bringing inconvenience to installation and transportation. In addition, its charging speed is slow, and a full charge may take several hours, which will affect the continuous operation time of the crane. At the same time, its cycle life is relatively short. Generally, after 300 - 800 charge-discharge cycles, the performance will decline significantly.

(2) Lithium-ion Batteries - Emerging Force

With the continuous innovation of battery technology, lithium-ion batteries are gradually emerging in the crane field. Lithium-ion batteries, with their high energy density characteristics, can store more power in a smaller volume and weight. For example, in some indoor cranes or port container cranes with strict requirements for space and weight, the advantages of lithium-ion batteries are particularly obvious. Taking the lithium-ion battery pack used in a certain port container crane as an example, compared with traditional lead-acid batteries, its weight is reduced by about one-third, but it can provide the same or even more lasting power output, greatly improving the energy utilization efficiency of the crane. Lithium-ion batteries also have the advantage of fast charging speed. Some fast charging technologies can fully charge the battery within 1 - 2 hours, effectively shortening the downtime waiting time and improving the operating efficiency of the crane. In addition, the cycle life of lithium-ion batteries is relatively long, up to 1000 - 3000 charge-discharge cycles, reducing the long-term use cost. However, the disadvantage of lithium-ion batteries is that the cost is relatively high, the initial investment is large, and the battery management system is required to be more strict to ensure its safety and stability.

II. Working Principles of Crane Batteries

Whether it is a lead-acid battery or a lithium-ion battery, their working principles essentially achieve the mutual conversion of electrical energy and chemical energy through electrochemical reactions.

During the discharge process of a lead-acid battery, lead dioxide at the positive electrode and lead at the negative electrode react with the sulfuric acid electrolyte respectively to form lead sulfate. In this process, electrons flow from the negative electrode to the positive electrode through the external circuit, thus generating an electric current to supply power to the crane. During charging, under the action of an external power source, lead sulfate is reduced back to lead dioxide and lead respectively, completing the storage of electrical energy into chemical energy.

When a lithium-ion battery is working, during the discharge process, lithium ions at the negative electrode escape from the lattice of negative electrode materials such as graphite, pass through the electrolyte and embed into the positive electrode materials. At the same time, electrons flow from the negative electrode to the positive electrode through the external circuit to form an electric current to drive the crane to operate. During charging, the process is reversed, and lithium ions escape from the positive electrode, pass through the electrolyte and return to the negative electrode to embed into the lattice, realizing the storage of electrical energy.

III. Factors Affecting the Performance of Crane Batteries

(1) Working Environment

Cranes often operate in various complex environments, and temperature has a significant impact on battery performance. In high-temperature environments, the internal chemical reaction speed of lead-acid batteries accelerates, which will lead to increased water loss in the battery and accelerated corrosion of the plates, thus shortening the battery life; lithium-ion batteries may have a thermal runaway risk, affecting safety and performance. In low-temperature environments, the electrical conductivity of the battery electrolyte deteriorates, the internal resistance of the battery increases, resulting in a decrease in battery capacity and output power, making it difficult for the crane to start in cold weather and weakening its lifting capacity. In addition, a humid environment may cause corrosion of the lead-acid battery casing, affecting its sealing. In an industrial environment with dust and corrosive gases, the casings and electrodes of both lead-acid batteries and lithium-ion batteries may be eroded, thereby affecting battery performance.

(2) Charging and Discharging Methods

Unreasonable charging and discharging methods are important factors that damage the life of crane batteries. Over-discharging, that is, continuing to use the battery after the power is exhausted, will cause sulfation of the plates of lead-acid batteries and damage to the structure of the negative electrode materials of lithium-ion batteries, seriously affecting the battery capacity and life. Frequent fast charging can save time, but it will generate more heat inside the battery and accelerate battery aging. Especially for lithium-ion batteries, long-term fast charging may lead to accelerated attenuation of battery capacity. In addition, putting the battery into use without sufficient charging will also keep the battery in a state of undercharge for a long time, reducing battery performance.

IV. Crane Batteries in Typical Application Scenarios

(1) Construction Sites

At construction sites, cranes are used to lift building materials, with frequent work and complex working conditions. Small tower cranes mostly use lead-acid batteries because of their low cost and ability to meet the needs of frequent starts and stops and short-distance lifting. However, with the improvement of environmental protection and efficiency requirements in construction, some large construction sites have begun to introduce electric cranes equipped with lithium-ion batteries. These lithium-ion battery-driven cranes can not only reduce noise pollution but also complete long-time and high-intensity lifting tasks more efficiently, improving the construction progress.

(2) Port Terminals

The cranes at port terminals have extremely high operating intensities and extremely high requirements for the battery's endurance and stability. The application of lithium-ion batteries in port cranes is gradually increasing. Their high energy density and long cycle life characteristics can ensure that the cranes can operate continuously for a long time and reduce the number of charging stops. For example, for quay container cranes, after using lithium-ion batteries, not only the operating efficiency is improved, but also the maintenance cost is reduced, which is in line with the development trend of green and efficient operation of ports.

V. Future Development Trends

With the continuous progress of science and technology, crane battery technology is also constantly innovating and developing. On the one hand, progress has been made in the research and development of new battery materials. For example, solid-state batteries are expected to be applied in the crane field. Compared with traditional lithium-ion batteries, solid-state batteries have higher energy density, better safety and longer cycle life, which will bring more powerful and lasting power to cranes. On the other hand, the battery management system will become more intelligent, capable of real-time monitoring of the battery state and precise control of the charging and discharging process, further improving battery performance and safety. At the same time, with the increasingly strict global environmental protection requirements, green and sustainable battery technologies will become the mainstream, which will not only help reduce the operating costs of cranes but also promote the entire industrial field to develop in a more clean and efficient direction. Crane batteries, as the key to the power of cranes, every breakthrough in their technology will bring far-reaching changes to industrial production and play an increasingly important role in the future industrial development.