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2025-09-03
What are the common charging methods for lithium batteries?
There are many ways to charge lithium-ion batteries. The most commonly used methods are constant current charging, constant voltage charging, constant current-constant voltage charging and pulse charging.(1) Constant current charging Constant current charging refers to charging the battery with a constant current. When constant current charging is performed with a single current value, if the charging current is too small, the charging time at the beginning of the charging phase will be too long. If the charging current is too large, the charging voltage of the battery will be too large in the later stages of charging, causing a greater impact on the electrodes. (2) Constant voltage charging Constant voltage charging refers to charging the battery while keeping the charging voltage constant. Although this method can automatically adjust the charging current according to the change of the battery SOC during the charging process, its disadvantages are also very obvious: the charging speed is slow, and the charging current is too large due to the low battery voltage in the early stage of charging, which will damage the battery, affect the battery life, and even cause the battery to be scrapped. (3) Constant current-constant voltage charging Constant current-constant voltage charging is currently the most commonly used charging method for lithium batteries. This method refers to first charging with a constant current until the battery voltage reaches a certain voltage value, and then charging the battery at a constant voltage. During the constant voltage charging stage, the charging current value of the battery will gradually decrease. When the charging current decreases to near zero or 0.02C, the battery is considered fully charged. This method combines the advantages of constant current charging and constant voltage charging: during constant current charging, it ensures that the current in the early stage of charging does not exceed the rated current of the battery; during constant voltage charging, the charging efficiency is improved.(4) Pulse chargingThe pulse charging method refers to charging the battery with a constant pulse current. In the initial stage of charging, the battery is first charged with a small current at a constant current. When the battery voltage is charged to a certain set voltage value, the battery is charged with a pulse current. This method provides sufficient time for depolarization operation, allowing the battery to store more energy.The figure below illustrates a typical charging process for a potassium-ion battery under constant current/constant voltage charging mode. The charging process is divided into two phases: constant current charging (t0-t1) and constant voltage charging (t1-t2).
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08-282025
Lithium Battery Pack Process: More Than Just “Assembly”
Many people simply equate lithium battery packs with "battery assembly." However, this process is actually a highly integrated system engineering process that combines electrochemistry, mechanical design, electronics, and thermal management. Every step is crucial to the performance, safety, and lifespan of the battery system.1. Cell Selection: The "Foundation" of the Packing Process, Consistency is KeyBuilding a reliable battery system begins with cell selection. Core requirements include performance consistency screening and on-demand selection. Voltage, internal resistance, and capacity are the three core parameters of a cell, and rigorous screening is required to ensure that each cell's parameters are perfectly matched. If a cell's capacity is 10% lower than others, it will charge and discharge first during long-term charge-discharge cycles, accelerating aging and potentially causing uneven charging and discharging across the entire battery pack, potentially posing a safety risk.2. Structural Design: Balancing Safety and Practicality in SpaceBattery packs must adapt to the end product and withstand the rigors of complex environments. Structural design requires finding the optimal balance between space, weight, and strength. For example, battery packs for new energy vehicles must be designed to closely fit the vehicle's spatial layout while also possessing a high-strength structure to withstand vibrations, bumps, and even collisions during driving, protecting the battery cells from crushing. Energy storage battery packs must also consider cabinet installation dimensions and ensure stacking stability. To reduce energy consumption, especially for automotive applications, battery packs utilize lightweight materials such as aluminum alloy and carbon fiber. However, lightweighting does not mean cutting corners. Engineers utilize topological optimization to strengthen the structure at key stress points, reducing weight while increasing rigidity and protecting the battery cells from damage due to vibration and impact.3. Electrical Connection: A Precise Path for Current and Signals. Even a single error is essential. After the battery cells are assembled, reliable electrical connections are crucial for powering the battery pack and are also a high-risk area for safety hazards. The busbar shape has been optimized to further reduce heat generation. The high-voltage wiring harness in the battery pack, responsible for transmitting high currents, must be thickened and kept away from heat sources. Low-voltage signal lines, responsible for transmitting data, must be routed away from the high-voltage harness to prevent EMI from causing erroneous data and misinterpretation by the BMS. All connections are insulated to prevent electrical creepage and breakdown. The entire battery pack must also meet IP ratings to ensure safety in rainy, submerged, and other environments.4.Thermal Management: The Battery's "Thermostat," Temperature Determines LifespanExcessively high lithium battery temperatures accelerate aging and may even cause thermal runaway. Excessively low temperatures lead to a sudden drop in capacity and slower charging. The thermal management system acts as the battery pack's "thermostat," maintaining an optimal temperature range of 25-40°C. Regarding heat dissipation, new energy vehicle battery packs often use liquid cooling. Liquid cooling plates embedded within the battery pack circulate coolant to remove heat, ensuring more uniform temperature control. Air cooling is cost-effective and simple, making it suitable for applications like energy storage batteries, where heat generation is relatively low. In winter, the battery pack activates its heating function, preheating the battery cells using PTC heating plates or electric heating films to prevent reduced battery life in winter.5. BMS: The "Brain" of the Battery Pack, the Core of IntelligenceIf the battery cell is the "heart" of the battery pack, then the BMS is the "brain," responsible for monitoring, protecting, and optimizing battery performance. The BMS uses sensors to collect real-time data on each cell's voltage and temperature, as well as the current flowing through the entire battery pack. It then uses algorithms to estimate the SOC and SOH, providing the user and the vehicle's control system with constant visibility into the battery's condition. Even if the cell parameters initially match, variations can develop over time. The BMS uses passive balancing (using resistors to discharge high-voltage cells to level the voltage) or active balancing (using energy transfer for greater efficiency and power savings) to prevent overcharging and discharging of individual cells, thereby extending the life of the entire battery pack. The BMS also has a series of preset "safety red lines." If any of these parameters, such as voltage, temperature, and current, are exceeded, the circuit will be immediately disconnected to prevent further damage. This serves as the battery pack's "last line of defense."In addition to the BMS, battery packs must also incorporate multiple safety features from other perspectives, such as electrical and mechanical safety. Before leaving the factory, battery packs must undergo three major tests: electrical performance, safety, and environmental adaptability. This ensures they can function properly in diverse environments and regions.
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08-202025
Types and key technologies of EV
Types of EV01Single battery as power sourceEV that uses a single battery as a power source only has a battery pack installed.02 Equipped with auxiliary power sourceAuxiliary power sources such as supercapacitors, generator sets, and solar energy are added to some EV to improve the starting performance of the EV and increase the driving range.How EV workIn EV, the electric motor drives the wheels using energy from the battery. The energy flow path is: battery → power conditioner → electric motor → drivetrain → drive wheels. The battery provides current, which passes through the power conditioner and is then output to the electric motor. The electric motor then provides torque, which, after passing through the transmission, drives the wheels, enabling the vehicle to move.Key technologies of pure electric vehicles01 Battery and Management TechnologyBatteries are the power source of electric vehicles and have long been a key factor restricting their development. Battery pack performance directly impacts the vehicle's acceleration, driving range, and brake energy regeneration efficiency. Battery cost and cycle life directly impact vehicle cost and reliability, and all parameters influencing battery performance must be optimized. Electric vehicle batteries generate significant heat during use, and battery temperature impacts the operation of the electrochemical system, cycle life, charge acceptability, power and energy, safety, and reliability. Therefore, to achieve optimal performance and life, battery pack temperature must be controlled within a certain range to minimize uneven temperature distribution within the pack and avoid imbalances between modules. This prevents battery performance degradation and mitigates potential hazards.02 Vehicle Control TechnologyThe control system for new EV utilizes a two-bus network structure: the high-speed CAN bus for the drive system and the low-speed bus for the body system. Each node on the high-speed CAN bus represents the ECU for each subsystem, while nodes on the low-speed bus are arranged according to physical location, based on the principle of regional autonomy based on spatial location. Implementing networked vehicle control not only addresses the complex wiring and increased wiring harnesses associated with automotive electronics, but also provides the communication and resource sharing capabilities enabled by networking, which form the foundation for the application of new electronic and computer technologies in automobiles and provides strong support for X-by-Wire technology.03 Vehicle Lightweighting TechnologyVehicle lightweighting technology has always been a key research topic in automotive technology. EV significantly increase vehicle weight due to the battery pack, making lightweighting a more significant issue. The following measures can be used to reduce vehicle weight:① By analyzing the vehicle's actual operating conditions and requirements, comprehensively optimize vehicle parameters such as battery voltage, capacity, drive motor power, speed, torque, and overall vehicle performance, and rationally select battery and motor parameters.② Reduce the weight of the powertrain and onboard energy system through structural optimization and integrated, modularized design. This includes integrating and modularizing the motor and drive, transmission system, cooling system, air conditioning, and brake vacuum system to optimize the system. System optimization is achieved through the rational integration and distribution of the onboard energy system, which includes the battery, battery pack, battery management system, and onboard charger.③ Actively select lightweight materials.④ Utilize CAD technology to conduct finite element analysis of the vehicle's load-bearing structural components (such as the front and rear axles, newly added side sills, and cross members), achieving structural optimization through a combination of calculation and testing.
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08-082025
China's first pure electric sea tourism passenger ship makes its maiden voyage in Xiamen!
Recently, China's first all-electric passenger ship, the "Yujian 77," officially launched in Xiamen Bay. This vessel not only offers tourists a zero-emission, low-noise, and high-quality marine tourism experience, but also demonstrates the feasibility of applying pure electric technology in offshore waters. This breakthrough marks the acceleration of the green transformation of the maritime tourism industry.The ship's battery system, equipped with the Yujian 77, innovatively utilizes CTP technology and an integrated CCS (high-voltage charging system) to achieve a battery pack energy density exceeding 140Wh/kg. This system provides the vessel with 3,918kWh of power, enabling a pure electric range of up to 100km, sufficient to support four consecutive Xiamen Bay night cruises."Yujian77"Furthermore, after its commissioning, the "Yujian 77" is expected to reduce fuel consumption by nearly 250 tons and CO2 emissions by over 400 tons annually, equivalent to the carbon sequestration capacity of planting over 20,000 trees.The application of pure electric propulsion technology in ships provides a new technological paradigm for the green development of maritime tourism and passenger transport.As an expert in marine batteries, Bosa offers not only 24V and 48V lithium-ion battery systems for small yachts, but also lithium-ion battery systems for large cruise ships, including design complete solutions for you. Welcome to contact us to discuss more possibilities.We are always on the road to promote green energy and reduce carbon emissions!