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2025-03-21
The difference between battery capacity and energy
The core difference between battery capacity and energy① Definition and unitCapacity: measures the ability of a battery to store charge, in Ah or mAh. For example, a 100Ah battery can discharge for 10 hours at a current of 10A.Energy: represents the total electrical energy released by the battery, in Wh or kWh. The calculation formula is Wh = V × Ah. For example, the energy of a 3.2V, 100Ah battery is 320Wh.② Differences in application scenariosCapacity: directly affects the endurance. The larger the capacity, the longer the endurance.Energy: determines the total endurance of the vehicle. The higher the energy density, the longer the endurance at the same volume.③ The significance in actual car purchaseCapacity: pay attention to the endurance, and need to combine the battery capacity and energy density for comprehensive judgment.Energy: pay attention to the energy density of the battery system. High energy density can reduce vehicle weight and improve energy efficiency.When purchasing a EV, you need to make a comprehensive judgment based on the balance of capacity and energy, battery type adaptability, fast charging and low temperature scene requirements
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03-142025
Why lithium battery charging is first constant current and then constant voltage charging
The constant current followed by constant voltage strategy in the lithium battery charging process is designed based on the physical characteristics and safety of the battery. This charging method not only ensures the safety of the battery, but also maximizes its capacity and prolongs its service life.Constant Current Charging StageIn the initial stage of lithium battery charging, the Constant Current (CC) mode is usually used. In this stage, the charger will provide a relatively stable current, which is generally set according to the design parameters of the battery.For a battery with a nominal capacity of 100Ah, a charging rate of 0.5C means a charging current of 50A.The main purpose of constant current charging is to quickly increase the battery voltage to a threshold close to the full charge state. This stage is effective because when the battery power is low, the internal resistance is small and can accept a larger charging current without causing overheating or damage.In addition, since the polarization phenomenon is weak at this time, charging with a larger current will not significantly affect the performance of the battery.Transition from constant current to constant voltageWhen the battery voltage reaches the set cut-off voltage, the constant current charging phase ends and the system automatically switches to Constant Voltage, (CV) mode.Continuing to charge at a constant high current may cause the battery voltage to rise rapidly, exceeding the safety limit, thereby damaging the battery structure and shortening its service life.During the constant voltage charging phase, the charger keeps the output voltage unchanged, but the charging current naturally decreases as the battery is gradually filled. This is because as the number of lithium ions inside increases, it becomes more difficult to further embed into the negative electrode, causing the internal resistance of the battery to rise, thereby reducing the current even at the same external voltage.Constant Voltage Charging PhaseDuring the constant voltage charging phase, the main goal is to gradually reduce the charging current until it reaches a predetermined low level, at which point the battery is considered fully charged.Despite the reduced charging current, the battery terminal voltage remains constant, allowing the remaining energy to be charged efficiently into the battery while avoiding the risk of overcharging.It should be noted that although the constant current charging phase can quickly increase the battery charge, it cannot complete the entire charging process alone. At the end of the constant current charging, there may be some polarization inside the battery, and the actual battery voltage may be lower than the measured voltage. Without subsequent constant voltage charging, the battery may not reach its maximum capacity, and long-term battery health may deteriorate.Polarization and safety considerationsWhen choosing a constant current followed by a constant voltage charging method, the polarization effect inside the battery should also be considered. Polarization refers to the situation in which the actual voltage of the battery is higher than the equilibrium voltage under ideal conditions due to the limitation of the electrochemical reaction rate during the charging process.The degree of polarization increases with the increase of charging current, which may cause the battery voltage to increase abnormally, or even trigger the protection mechanism to terminate charging prematurely. Introducing a constant voltage stage helps to make the ion concentration distribution inside the battery more uniform, reduce the polarization effect, and ensure that the battery can be fully charged without overheating or damage.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack
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02-282025
Why do prismatic shell batteries need blue film?
The main reason for wrapping the blue film on the outside of square lithium-ion batteries involves functional requirements and process considerations in many aspects. The following is a detailed explanation:1. Insulation protection and anti-short circuit design:The outer shell of prismatic shell batteries is usually made of metal (such as aluminum alloy). Direct contact may cause short circuits between batteries or external components. The blue film acts as an insulating layer to effectively isolate the metal surface and prevent accidental conduction.Enhanced safety: In scenarios where battery packs are densely arranged, the blue film reduces the risk of short circuits caused by outer shell contact and improves overall safety.2. Anti-corrosion and sealed environmental protection:The blue film can isolate corrosive environmental factors such as moisture, salt spray, acidic and alkaline substances, delay oxidation and rust of the metal shell, and extend battery life.Sealing assistance: Some blue film materials have waterproof and dustproof properties, and cooperate with battery packaging technology to further improve the sealing.3. Mechanical protection against physical damage:During transportation, assembly or use, the blue film can reduce the damage to the battery shell caused by scratches and collisions, and avoid the exposure of the internal structure or electrolyte leakage due to shell damage.Buffering effect: Some blue films are elastic and can absorb slight impacts to protect the structural stability of the internal pole pieces and diaphragms of the battery.4. Thermal management and auxiliary heat dissipation optimization:Some blue film materials have added thermal conductive particles (such as ceramics and graphite) to help evenly distribute the surface temperature of the battery and avoid local overheating. At the same time, dark colors (such as blue) may be more conducive to heat radiation.Insulation function: In extremely high temperature environments, the blue film may serve as an insulation layer to reduce the impact of external heat on the battery.5. Identification and management model distinction:Blue is often used to identify specific battery models, capacities or voltage levels, which facilitates quick identification during sorting and maintenance of the production line.Brand recognition: Manufacturers use unified colors (such as CATL's iconic blue film) to strengthen their brand image and prevent counterfeiting.Traceability information: Some blue films are printed with QR codes or batch numbers, and the color can be combined to quickly trace production data.6. Process and cost optimization Automation adaptation:The blue film has high contrast in the visual inspection system, which is convenient for machine vision positioning, detection of coating integrity, and improved production efficiency.Material cost: Insulation film materials such as blue PET (polyester) are mature and low-cost, balancing performance and economic benefits.7. Special functional requirements Flame retardant performance:Some blue films are added with flame retardants to delay the spread of fire when exposed to high temperatures, meeting battery safety standards.Anti-ultraviolet: Blue pigments may have better UV resistance, delay film aging, and are suitable for outdoor energy storage scenarios.SummaryThe blue film of prismatic shell batteries is not just a simple packaging, but a key component that integrates insulation, protection, thermal management, and identification.Its color selection (blue) may be due to technical considerations (such as heat dissipation, detection adaptation), or it may be part of the manufacturer's brand strategy.In actual applications, the specific characteristics of the blue film will vary depending on the battery application (such as power battery, energy storage battery) and manufacturer design.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack
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02-142025
Lithium battery insulation resistance test standard and analysis of adverse causes
1. Commonly used lithium battery resistance (IR) insulation resistance test standards① IEC 62133IEC 62133 is a standard formulated by the International Electrotechnical Commission, which applies to the safety performance requirements and test methods of lithium batteries and lithium battery packs. This standard places clear requirements on the resistance (IR) insulation resistance test of lithium batteries to ensure the accuracy and reliability of the test results.② UL 2054UL 2054 is a standard formulated by the American Safety Laboratory and is applicable to the safety performance requirements and test methods of lithium batteries. This standard also specifies the requirements for resistance (IR) insulation resistance testing of lithium batteries to ensure the safe performance of the battery during use.③ GB/T 18287GB/T 18287 is a standard formulated by the China National Standardization Management Committee and is applicable to general specifications for mobile phone batteries and lithium-ion batteries. This standard puts forward corresponding requirements for the resistance (IR) insulation resistance test of lithium batteries to ensure the performance and quality of the battery.2. Analysis of the results and reasons for poor insulation resistance testIn the resistance (IR) insulation resistance test of lithium batteries, poor test results may occur. These adverse results may be caused by the following reasons:① Manufacturing process problems: Problems during the manufacturing process, such as material defects and poor process control, may lead to defects such as impurities or cracks inside the battery, thereby affecting the test results of the insulation resistance.②Temperature influence: Temperature is one of the important factors affecting the performance of lithium batteries. Too high or too low temperature may affect the chemical reaction and ion transport inside the battery, thereby affecting the test results of insulation resistance.③ Charge status: The charging status of the lithium battery will also affect the test results of its insulation resistance. Overcharging or discharging may lead to problems such as decomposition of the electrolyte inside the battery and structural changes of the positive and negative electrode active substances, which will affect the test results of the insulation resistance.④ External pressure: Changes in external pressure may also affect the insulation performance of lithium batteries. Excessive pressure may lead to problems such as leakage of electrolyte inside the battery, short circuit of the positive and negative electrodes, etc., which will affect the test results of the insulation resistance.⑤ Aging: As the use time increases, the aging degree of lithium batteries will also affect the test results of their insulation resistance. Aging may lead to problems such as evaporation of the electrolyte inside the battery and failure of the positive and negative electrode active substances, which will affect the test results of the insulation resistance. Therefore, for lithium batteries that have been used for a long time, the insulation resistance test should be carried out regularly.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 5GWh ESS in 2023. In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack
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