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Global demand for Li-ion batteries (LIBs) is increasing and expected to reach 4. 1 These goals are vital for climate change mitigation but introduce two challenges: battery material demand and future battery waste. 6 The US Inflation Reduction Act (IRA) provides investment tax credits for battery recycling projects and ofers tax credits for vehicles using materials extracted or processed in the US or a free trade partner,7,8 encouraging recycling to reduce materials imports.
The Tesla Megapack is a large-scale stationary product, intended for use at, manufactured by, the energy subsidiary of Launched in 2019, a Megapack can store up to 3.9 megawatt-hours (MWh) of electricity. Each Megapack is a container of similar size to an. They are designed to be depl.
Capacity, Specs & More A Tesla battery pack varies in size depending on the model. The Model S and Model X use a small pack measuring 68.5 x 30 x 75 cm. In contrast, the Model 3 features a large pack measuring 185.4 x 29.2 x 9 cm. Understanding these measurements helps when choosing the right pack for your needs.
The Model Y Battery Pack shares the architecture with the Model 3. Its approximate dimensions are 60 x 50 x 8 inches. It has similar variants in capacity ranging from 50 kWh to 75 kWh, designed for efficiency and range, catering to compact SUV markets.
Energy Requirements: Energy requirements directly impact the size of a Tesla battery pack. Larger battery packs provide more energy, allowing for longer driving ranges. For example, the Tesla Model S with a 100 kWh battery pack can travel approximately 370 miles on a single charge. Vehicle Type: The type of vehicle also influences battery size.
The entire pack weighs around 450kg, making it one of the most giant battery packs in any production car today. Despite its size, the Roadster's battery pack is quite efficient, powering the car for over 400 km on a single charge. See Also: Can An Electric Car Charge While Driving? What Batteries Does Tesla Use?
The battery pack dimensions approximately measure 72 x 36 x 7 inches. The pack is capable of delivering up to 100 kWh, providing a long range and exceptional performance. Tesla's advancements in battery technology allow for faster charging times. The Model 3 Battery Pack also utilizes the 2170 cell format.
The Model X Battery Pack has similar dimensions to the Model S but is uniquely designed to accommodate the vehicle's weight and size. Its dimensions are around 72 x 36 x 7 inches, with a capacity of up to 100 kWh. The pack's robust design supports the SUV's performance and safety features.
Each lithium battery has a positive (+) and a negative (-) terminal. Correctly identifying these terminals is key for safe and effective use. Interchanging them can result in serious device damage.
Maybe you have noticed that, for example, car lithium batteries always have cylinder shaped terminals, motorcycle batteries have square shaped terminals, some other terminals are simple tabs sticking straight out of the top of lithium batteries. How to Reduce Poor Connection Chances? What's the Difference between Terminals and Lugs?
Most consumer devices that have lithium single-cell batteries have 4 connections. I've noticed the following diverse types of devices, this is true: The 4-connection rule seems to hold even with devices that have multi-cell batteries like cordless drills.
Lead terminals are hence a stable, reliable choice for lithium batteries. The Significance of Terminal Material in Lithium Batteries! Lithium battery terminals are vital for battery efficiency.
When it comes to lithium batteries, there exists a diverse array of terminal configurations to suit different applications and devices. Two common types include button top and flat top terminals. Button top terminals feature a raised positive terminal that resembles a small button on top of the battery cell.
In lithium ion battery systems, there exist two such connectors – the battery terminals positive and negative. On one side, the positive terminal connects to the cathode of the battery. Then, the negative terminal connects to the battery's anode. A safe and secure connection is vital for a battery's efficient operation.
The electrical energy in batteries travels through their terminals the, cathode and the anode, or what we like to call positive and negative terminals. Lithium batteries come in many shapes and sizes, so do lithium battery terminals. The application range of lithium battery is quite wide from bracelet to car.
There are several options that can be used in to help mitigate the risk presented by lithium-ion battery charging, they include:Place the battery in an appropriately located fire compartment with access for maintenance and repair. Environmentally controlled environments, to prevent overheating of the space. Provide battery thermal management devices that automatically cut charging if issues detected.
Over the past four years, insurance companies have changed the status of Lithium-ion batteries and the devices which contain them, from being an emerging fire risk to a recognised risk, therefore those responsible for fire safety in workplaces and public spaces need a much better understanding of this risk, and how best to mitigate it.
There are several options that can be used in to help mitigate the risk presented by lithium-ion battery charging, they include: Place the battery in an appropriately located fire compartment with access for maintenance and repair. Environmentally controlled environments, to prevent overheating of the space. Fire Detection. Fire Suppression.
With the advantages of high energy density, short response time and low economic cost, utility-scale lithium-ion battery energy storage systems are built and installed around the world. However, due to the thermal runaway characteristics of lithium-ion batteries, much more attention is attracted to the fire safety of battery energy storage systems.
A survey of more than 500 organisations carried out between September 2023 and February 2024 revealed that 71 per cent of respondents had not updated their fire risk assessments to cover the risk of Lithium-ion battery fires, with just 15 per cent having done so and a further 14 per cent unsure.
This guide focusses on fire hazards and good-practice risk control measures for the charging of EVs using lithium-ion batteries, driven on highways, (i.e. cars, motorcycles, bicycles, lorries, coaches/buses, etc.) Lithium-ion batteries are the predominant type of rechargeable battery used in EVs.
Specific risk control measures should be determined through site, task and activity risk assessments, with the handling of and work on batteries clearly changing the risk profile. Considerations include: Segregation of charging and any areas where work on or handling of lithium-ion batteries is undertaken.
A lead-acid battery consists of two lead plates separated by a liquid or gel containing sulfuric acid in water. The battery is rechargeable, with charging and discharging chemical reactions. When the battery is being used (discharged), electrons move from the negatively-charged lead plate to the positively-charged plate. The. When the battery is fully charged, the negative plate is lead, the electrolyte is concentrated sulfuric acid, and the positive plate is lead dioxide. If the battery is overcharged, electrolysis of water produces hydrogen gas. Calling sulfuric acid"battery acid" gives an indication of the acid concentration. There are, in fact, several different names for sulfuric acid that typically reflect its usage. 1. Concentration less than.
The battery acid is made of sulfuric acid (H2So4) diluted with purified water to get an overall concentration of around 29-32, a density of 1.25-1.28 kg/L, and a concentration of 4.2 mol/L. The pH value of electrolytes is about 0.8, so we need to take utmost care when handling battery acid. What Is Battery Acid?
Batteries contain acid because it's fundamental to the electrochemical reaction that takes place. Also referred to as battery electrolyte, battery acid is the medium that carries the electrical flow between positive and negative electrodes.
Car battery acid is around 35% sulfuric acid in water. Battery acid is a solution of sulfuric acid (H 2 SO 4) in water that serves as the conductive medium within batteries. It facilitates the exchange of ions between the battery's anode and cathode, allowing for energy storage and discharge.
Battery acid primarily refers to sulfuric acid, with the chemical formula H2SO4. Now, if we break that down, we get two hydrogen atoms, one sulfur atom, and four oxygen atoms working together in harmony to perform a critical role in the battery's operations. Think of it as the fuel that powers the entire battery system. Why Sulfuric Acid?
Battery acid (AKA sulfuric acid) is used in lead-acid batteries to help create and store electrical energy, which powers many devices and vehicles.
These batteries are highly corrosive, and react vigorously with the skin, causing burns and irritation. Battery acids have a high electrical conductivity. Usually, these acids are colorless. However, they can easily pick on impurities. The density of an acid battery is twice that of water.
Below is a detailed explanation of the primary technical parameters of lithium batteries, along with additional related knowledge, to assist you in better applying and managing energy storage systems.
Learn about the key technical parameters of lithium batteries, including capacity, voltage, discharge rate, and safety, to optimize performance and enhance the reliability of energy storage systems. Lithium batteries play a crucial role in energy storage systems, providing stable and reliable energy for the entire system.
Lithium batteries play a crucial role in energy storage systems, providing stable and reliable energy for the entire system. Understanding the key technical parameters of lithium batteries not only helps us grasp their performance characteristics but also enhances the overall efficiency of energy storage systems.
Specific capacity, energy density, power density, efficiency, and charge/discharge times are determined, with specific C-rates correlating to the inspection time. The test scheme must specify the working voltage window, C-rate, weight, and thickness of electrodes to accurately determine the lifespan of the LIBs. 3.4.2.
Energy density is often a more relevant indicator than capacity in practical applications. Current lithium-ion battery technology achieves energy densities of approximately 100 to 200 Wh/kg. This level is relatively low and poses challenges in various applications, particularly in electric vehicles where both weight and volume are restricted.
LIBs are prominent energy storage devices to meet the growing energy demands of the modern era. They offer high specific capacity, energy density, thermal stability, and long calendar life compared to other types of batteries. LIBs are used in a diverse range of applications, from powering household appliances to supporting electric vehicles.
Battery storage is a technology that enables power system operators and utilities to store energy for later use.
The liquid-filled lead acid batteries used in automobiles and a range of other products have many great qualities, but are also known to “go bad” with little warning. Fortunately, you can easily do a basic health checkup on any.
Lead acid batteries recharge in various manners based on their function and manner of installation. For a lead acid vehicle battery, drive the vehicle around for at least 20 minutes. For a lead acid battery connected to solar panels, let the battery charge fully on a sunny day.
Fortunately, you can easily do a basic health checkup on any type of lead acid battery by hooking it up to a simple-to-use digital voltmeter. If you have an open-cell battery that lets you access the liquid inside, you can do a more rigorous checkup with a battery hydrometer. Charge the battery fully, then let it rest for 4 hours.
The liquid-filled lead acid batteries used in automobiles and a range of other products have many great qualities, but are also known to “go bad” with little warning. Fortunately, you can easily do a basic health checkup on any type of lead acid battery by hooking it up to a simple-to-use digital voltmeter.
Lead-acid batteries are a type of rechargeable battery that uses lead and lead oxide electrodes submerged in an electrolyte solution of sulfuric acid and water. They are commonly used in vehicles, backup power supplies, and other applications that require a reliable and long-lasting source of energy.
To get a more accurate reading of a lead-acid battery's health, you can use a hydrometer. This tool measures the specific gravity of the electrolyte solution within the battery, which can give you a better idea of its state of charge and overall condition. Before using a hydrometer, it's important to make sure the battery is fully charged.
Checking an open-cell lead acid battery—that is, a lead acid battery with caps that can be opened to access the liquid inside—with a battery hydrometer is most accurate when the battery is fully charged. Closed-cell lead acid batteries without the access caps cannot be tested this way.
These include:Ensuring batteries are separated from habitable rooms and escape routes by appropriate fire compartmentation. Providing fire detection for the battery location, linked to a fire alarm system to alert inhabitants of a fire.
To minimise the risk of batteries becoming a fire hazard, a new British Standard covering fire safety for home battery storage installations came into force on 31 March 2024. The standard is – PAS 63100:2024: Electrical installations. Protection against fire of battery energy storage systems (BESS) for use in dwellings.
With this in mind, it's reasonable to question the fire risks posed by home battery storage systems. As we explain below, home battery fire risk is not something you need to lose sleep over. Read on to find out more. Why do batteries catch fire? Li-on batteries are essential in modern society.
It should be noted that fires from domestic home energy storage batteries are extremely rare. Most Home energy batteries use Lithium Iron Phosphate technology (LiFePO4). Whilst this technology makes for a heavier battery, it is known to be very safe and does not catch fire under any normal circumstances.
In September 2020, the UK government published a review of safety risks related to domestic battery energy storage systems. In the document, it acknowledges that 'few incidents with domestic battery energy storage systems are known in the public domain'. At the same time, the report recognises that relevant safety measures need to be implemented.
Even though few incidents with domestic battery energy storage systems (BESSs) are known in the public domain, the use of large batteries in the domestic environment represents a safety hazard.
Battery energy storage systems (BESS), also known as Electrical Energy (Battery) Storage systems or solar batteries, are becoming increasingly popular for residential units with PV solar installations, and (although much less frequently) small wind-turbines¹.
Before the 2000s, lithium-ion battery production was dominated by Japan with its superior technologies, by companies like. Japan alone made 88% of the world's battery supply. In the following two decades, China invested heavily in its sourcing and manufacturing processes. Since 2015, China surpassed Japan, Korea, and the rest of the world and became the largest exporter of lithium batteries. Combined with Japan and Korea, the countries account for 95% of.
China produced more than 15 billion units of lithium-ion batteries in 2019, which accounts for 73% of the world's 316 gigawatt-hours capacity. China is a significant producer of lithium batteries and electric vehicles, supported by government policies.
Bali, November 12, 2022 – China continues to dominate BloombergNEF's (BNEF) global lithium-ion battery supply chain ranking, for the third time in a row, for both 2022 and its projection for 2027, thanks to continued support for the electric vehicle demand and raw materials investments.
Source: The General Administration of Customs of China China's crucial role in the development of lithium batteries can be highlighted by its lithium cell manufacturing capacity which accounts for 73% of the world's 316 gigawatt-hours capacity.
Since 2015, China surpassed Japan, Korea, and the rest of the world and became the largest exporter of lithium batteries. Combined with Japan and Korea, the countries account for 95% of lithium battery production in the world. China has the fourth-largest known lithium reserve with 1 million tons, behind Chile, Australia, and Argentina.
In the 1990s, China had its first breakthrough with its state enterprise China Electronics Corporation successfully developing its own Model 18650 lithium battery which was ready for mass production.
The market capitalization for lithium batteries in China is estimated at 190 billion yuan (approximately 30 billion dollars) and is projected to reach 268 billion yuan (42 billion dollars) by 2026.
LiFePO4 batteries are generally considered to be safe. They do have some potential safety risks to be aware of. For example, they can still catch fire if damaged or subjected to extreme conditions, such as high temperatures or physical impact. It is important to handle LiFePO4 batteries with care and follow proper. To ensure the safety of LiFePO4 batteries, it is important to handle and maintain them properly. This includes charging them using a compatible. Compared to other lithium-ion battery chemistries, such as lithium cobalt oxide and lithium manganese oxide, LiFePO4 batteries are generally. Overall, LiFePO4 batteries are considered to be a safe choice for a variety of applications due to their high level of stability and built-in protection features.
Other lithium-ion battery chemistries, such as lithium cobalt oxide (LiCoO2) and lithium manganese oxide (LiMn2O4), have a high level of safety. Still, they have a higher risk of thermal runaway and overheating than LiFePO4 batteries.
Many still swear by this simple, flooded lead-acid technology, where you can top them up with distilled water every month or so and regularly test the capacity of each cell using a hydrometer. Lead-acid batteries remain cheaper than lithium iron phosphate batteries but they are heavier and take up more room on board.
LiFePO4 batteries are known for their high level of safety compared to other lithium-ion battery chemistries. They have a lower risk of overheating and catching fire due to their more stable cathode material and lower operating temperature. We have also mentioned this in our best LiFePO4 battery list.
One of the most attractive features of Lithium-ion batteries is their quick charging time compared to traditional lead acid batteries, making them an attractive option for those who work and live aboard. Credit: Cultura Creative RF/Alamy Credit: Cultura Creative RF/Alamy Lithium iron phosphate batteries: myths BUSTED!
Rechargeable lithium batteries have become an essential part of modern life, powering everything from portable electronics to solar energy systems. However, they are often surrounded by safety concerns—one of the most persistent myths being that these batteries pose a significant fire hazard.
A Comprehensive Guide LiFePO4 batteries, also known as lithium iron phosphate batteries, are rechargeable batteries that use a cathode made of lithium iron phosphate and a lithium cobalt oxide anode. They are commonly used in a variety of applications, including electric vehicles, solar systems, and portable electronics.
Cycle life can be negatively impacted when batteries from different manufacturers are charged in the same manner. Even the same types of batteries, such as Li-lon and NiMH, may require separate charging considerations. Inspection of the manufacturer's data sheet revealed that some types of NiMH batteries can take a. Insufficient run time is caused by undercharging the battery, which can happen by misapplying technology. For example, charging of a 4.2. By ensuring proper Li-Ion and NiCd battery charging, your result is improved time-to-market, reduced development costs, and a finely tuned battery and charger system. Avoiding all of these overarching concerns. The "one stop shop" approach to custom battery packsand chargers is extremely beneficial to the person purchasing the batteries and chargers. If the battery pack and charger are ordered.
[PDF Version]The blue wire W1 must be connected to the opposite end of the battery pack as the black wire at the top of the battery pack. When batteries are connected in parallel, only use one charger. Do not connect a charger to each battery, unless you break the electrical connection between the batteries.
To charge the battery, set the charger to the appropriate settings as indicated in the user manual. Turn on the charger and monitor for any unusual signs such as overheating or fumes. The charging time will vary based on the battery size and charger type.
Do not mix and match different battery voltages in the same battery pack. In this example the battery pack voltage is 12 volts which is exactly the same as each of the individual 12-volt batteries. The capacity of the battery pack is the sum of the capacities of the individual batteries.
Batteries connected in series strings can also be recharged by a single charger having the same nominal charging voltage output as the nominal battery pack voltage. In Figure 8, a single 24-volt charger is connected to a 24-volt battery pack. In Figure 9 we see a pair of 12-volt batteries connected in parallel.
How to use a battery charger and the battery type should be determined first—lead-acid, lithium-ion, or any other—as each requires a different charger. To ensure a smooth connection, match the charger and battery voltage and amperage specifications.
When batteries are connected in parallel, only use one charger. Do not connect a charger to each battery, unless you break the electrical connection between the batteries. The reason is that the chargers will very likely complete one or more their charging subroutines (charge modes or stages) at different times.
The increase in battery demand drives the demand for critical materials. In 2022, lithium demand exceeded supply (as in 2021) despite the 180% increase in production since 2017. In 2022, about 60% of lithium, 30% of cobalt and 10% of nickel demand was for EV batteries. Just five years earlier, in 2017, these shares were. In 2022, lithium nickel manganese cobalt oxide (NMC) remained the dominant battery chemistry with a market share of 60%, followed by lithium iron phosphate (LFP) with a share of just under 30%, and nickel cobalt aluminium. With regards to anodes, a number of chemistry changes have the potential to improve energy density (watt-hour per kilogram, or Wh/kg). For example, silicon can be used to replace all or some of the graphite in the anode in.
The global sodium-ion battery market size was estimated at USD 321.75 million in 2023 and is expected to grow at a CAGR of 16.3% from 2024 to 2030. The global market is experiencing significant growth and is poised for further expansion in the coming years.
The market for sodium-ion batteries was estimated to be worth roughly USD 1120 million in 2021, and it is anticipated to grow to USD 2899 million by 2030. The market is expected to grow significantly over the coming years as a result of a number of driving factors.
Sodium-ion batteries play a crucial role in the transition towards cleaner and more abundant energy storage technologies and drive the Sodium-Ion Battery Market. The sodium-ion battery market demand is driven by the growing integration of renewable energy sources.
The sodium ion battery market in the U.S. is expected to grow at a CAGR of 18.9% from 2024 to 2030. Increasing demand for sodium-ion batteries from sectors like electric utilities, transportation (potentially for low-range EVs or commercial fleets), and industrial applications requiring reliable and cost-effective energy storage.
The sample report only takes 30 secs to download, no need to wait longer. The global sodium-ion battery market size was valued at USD 1025 million in 2021 and is estimated to reach an expected value of USD 2665 million by 2030, growing at a CAGR of 11.2% during the forecast period (2022 - 2030).
The Sodium-ion Battery market is divided into types and end-users for the purposes of our study. The sodium-Sulfur batteries category is predicted to rule the sodium-ion battery market in 2021 based on type. In sodium-sulfur (NAS) batteries, a type of sodium-ion battery, there is a lithium sulphide cathode and a sodium anode.
A lithium battery pack immersion cooling module for energy storage containers that provides 100% heat dissipation coverage for the battery pack by fully immersing it in a cooling liquid.
Based on our comprehensive review, we have outlined the prospective applications of optimized liquid-cooled Battery Thermal Management Systems (BTMS) in future lithium-ion batteries. This encompasses advancements in cooling liquid selection, system design, and integration of novel materials and technologies.
Immersed liquid-cooled battery system that provides higher cooling efficiency and simplifies battery manufacturing compared to conventional liquid cooling methods. The system involves enclosing multiple battery cells in a sealed box and immersing them directly in a cooling medium.
To ensure the safety and service life of the lithium-ion battery system, it is necessary to develop a high-efficiency liquid cooling system that maintains the battery's temperature within an appropriate range. 2. Why do lithium-ion batteries fear low and high temperatures?
However, lithium-ion batteries are temperature-sensitive, and a battery thermal management system (BTMS) is an essential component of commercial lithium-ion battery energy storage systems. Liquid cooling, due to its high thermal conductivity, is widely used in battery thermal management systems.
Under this trend, lithium-ion batteries, as a new type of energy storage device, are attracting more and more attention and are widely used due to their many significant advantages.
An immersion cooling system for lithium-ion battery packs that uses glycol-based coolant and a sealed case to cool the batteries uniformly and efficiently. The battery pack has cells held by cell holders inside a sealed case filled with coolant. The coolant surrounds the cells and circulates to extract heat.
This article summarizes top 10 manufacturers of global energy storage batteries. They are CATL, BYD, EVE, REPT,HTHIUM, Great Power, Envision Energy, CALB, GOTION HIGH-TECH, Ganfeng Lithium.
This article will mainly explore the top 10 energy storage manufacturers in the world including BYD, Tesla, Fluence, LG energy solution, CATL, SAFT, Invinity Energy Systems, Wartsila, NHOA energy, CSIQ. In recent years, the global energy storage market has shown rapid growth.
As the top battery energy storage system manufacturer, The company is renowned for its comprehensive energy solutions, supported by advanced industrial facilities in Shenzhen, Heyuan, and Hefei. Grevault, a subsidiary of Huntkey, is a leader in the battery energy storage sector.
First, we'll take a look at the top 10 quoted batteries on the EnergySage Marketplace: Enphase takes the top place with its IQ 10 Battery, which includes 10.08 kilowatt-hours (kWh) of usable capacity.
On the EnergySage Marketplace, the most popular battery brands include Enphase and Tesla. In the first quarter of 2022, the most commonly quoted and selected battery on the Marketplace nationwide was the Enphase IQ 10 Battery.
LG Chem, a branch of the LG conglomerate, boasts a rich lineup of lithium-ion batteries. Their RESU series, known for its compactness and efficiency, is popular among homeowners seeking solar energy storage solutions. 4.3. Panasonic Once Tesla's primary battery cell provider, Panasonic is an industry veteran with over a century of experience.
LG Energy Solution, coming in at third, has the most battery models in the top 10 spots: the RESU 10H, RESU Prime 16H, and RESU Prime 10H are among the most quoted batteries on the EnergySage Marketplace.
When the electrolyte in a lithium-ion battery freezes, it can cause the formation of lithium metal on the surface of the electrodes inside the battery. This can create a physical barrier that prevents the flow of ions between the. To maximize the efficiency of a lithium-ion battery at low temperatures, there are several strategies that can be used: 1.Keep the battery warm: One of the most effective ways to maintain. The runtime of a lithium-ion battery depends on several factors, including the capacity of the battery, the power requirements of the device.
Low-temperature batteries are designed to maintain performance in cold environments. In contrast, standard batteries often experience reduced capacity and efficiency in low temperatures.
Battery certification plays a crucial role in ensuring the safety and performance of battery products across various industries. In this guide, we'll break down the essential certifications you need to know, including the types of certifications, the costs involved, expected timeframes, and the standards that govern them.
Low-temperature batteries may sacrifice some capacity or energy density to maintain performance in cold environments. In contrast, standard batteries typically offer higher capacity and energy density under normal operating conditions. Standard batteries may perform better in moderate temperatures but struggle in colder climates.
The lowest temperature at which most batteries can operate without damage is typically around -20 °C to -40 °C (- 4°F to 40°F). However, this can vary depending on the type of battery and its chemistry. What is the low temperature for a LiPo battery? LiPo batteries perform best at temperatures above 0°C (32°F).
LiFePO4 batteries can generally operate safely down to around -20°C. Beyond this temperature, their performance may decline, potentially damaging them. The low temperature li-ion battery solves energy storage in extreme conditions. This article covers its definition, benefits, limitations, and key uses.
In Europe, lithium-ion batteries must meet CE Marking requirements for safety, health, and environmental standards. Additional certifications like IEC 62133 or UN38.3 may be needed for transport and use. What to consider when choosing a certification body?
In this article, we will examine a circuit that allows charging Li-ion cells connected in series while also balancing them during the charging process.
The following graph suggests the ideal charging procedure of a standard 3.7 V Li-Ion Cell, rated with 4.2 V as the full charge level. Stage#1: At the initial stage#1 we see that the battery voltage rises from 0.25 V to 4.0 V level in around one hour at 1 amp constant current charging rate. This is indicated by the BLUE line.
If the cells are protected and one cell charges faster than the other it's protection will cut it off and current will not flow the other battery in series. That is the function of battery management circuits. Lithium ion batteries are fully charged at 4.2V, and discharged at about 3 V.
Although Li-Ion batteries are vulnerable devices, these can be charged through simpler circuits if the charging rate does not cause significant warming of the battery., and if the user does not mind a slight delay in the charging period of the cell.
It is possible to charge the cells individually, but limit the current and don't exceed 4.2V, and monitor the battery temperature. Many lithium batteries have built in protection for overdischarge.
The charging also different than the lead-acid batteries. The 3.9v Lithium-ion batteries need 4.2 v of charging voltage and 1A charging current. The charging time is about 2-3 hours. if the optimized charging is not done, the battery will be damaged or reduces the battery capacity.
You can also view the Lithium battery Charger PCB, how it will look after fabrication using the Photo View button in EasyEDA: After completing the design of this Lithium battery Charger PCB, you can order the PCB through JLCPCB.com. To order the PCB from JLCPCB, you need Gerber File.