6-Steps to Lithium Battery PACK Assembly

6-Steps to Lithium Battery PACK Assembly

For more information, please visit prismatic lithium battery laser welding machine.

Lithium Battery Capacity Grading

Lithium battery capacity grading refers to the process of determining the amount of energy a battery can store and deliver. This grading is essential for ensuring that batteries meet the specified performance standards and the requirements of various applications. The following steps are involved in battery capacity grading:

1. Design Specification: Determine the design specifications of the battery, including the required capacity, voltage, energy density, and discharge rate.
2. Testing Procedure: Establish a standardized testing procedure to evaluate the battery's performance, including setup of test equipment, measurement techniques, and data acquisition systems.
3. Sample Preparation: Prepare a representative sample of batteries for testing by selecting a random sample from the production line or testing a subset of a larger batch.
4. Capacity Testing: Perform capacity testing by discharging the battery at a specified rate and measuring the voltage and current during the discharge process. Calculate the capacity based on the amount of energy delivered during discharge.
5. Data Analysis: Analyze the data from capacity testing to determine the battery's performance, which may involve calculating average capacity, capacity distribution, and other relevant parameters.
6. Grading: Assign a grade to the battery based on its performance compared to the design specifications, which may include defining different grades, such as "A Grade," "B Grade," or "C Grade."

These steps are critical for ensuring that batteries are accurately and consistently graded based on their performance and that they meet the requirements of various applications.

Lithium Battery Laser Welding Process and Advantages

Lithium battery laser welding is a common method used in battery pack assembly for joining metal components together. Process:

1. Preparation: Clean and position the components to be welded accurately.
2. Alignment: Align the laser beam to the desired welding position using laser optics.
3. Welding: Focus the laser beam onto the surface of the components, generating heat that melts the metal and fuses the components. Control the laser power and duration to achieve the desired welding quality and strength.
4. Cooling: Allow the components to cool naturally or with forced cooling, depending on the desired final properties of the weld.

It's important to note that laser welding is a complex process requiring careful control of the laser beam and the components being welded. Skilled operators and proper equipment are essential for achieving consistent, high-quality results.

If you are considering implementing laser welding in your battery pack assembly process, it's recommended to seek the assistance of experts in the field to help choose the appropriate equipment and set up the process correctly.

Advantages:
Laser welding offers several advantages over traditional welding methods in battery pack assembly:

1. Precision: Allows for precise and accurate welding of small and intricate components, ideal for joining battery cells and other small components in battery packs.
2. Speed: A fast process that permits higher production rates compared to other welding methods.
3. Repeatability: Enables consistent and repeatable results, reducing the risk of defects and improving battery pack quality.
4. Minimal Heat-Affected Zone (HAZ): The small focused beam size results in a small heat-affected zone, reducing the risk of damaging sensitive battery components or altering their properties.
5. Cleanliness: Generates minimal fumes and spatter, reducing the need for cleaning and post-weld treatment, crucial in battery assembly where cleanliness is vital.
6. Flexibility: Can be used for a variety of materials, including metals and alloys, making it a versatile option for battery pack assembly.

In conclusion, laser welding can provide significant benefits in terms of precision, speed, repeatability, minimal heat-affected zone, cleanliness, and flexibility compared to traditional welding methods, making it a popular choice in battery pack assembly.

Lithium Battery Cell Detection

Lithium (LiFePO4 or LFP) batteries are a type of rechargeable battery commonly used in various applications, including electric vehicles and solar energy storage systems. To check the health of a LiFePO4 battery cell, use the following methods:

1. Voltage Measurement: Measure the voltage of each cell using a multimeter. A fully charged LiFePO4 cell should measure around 3.2-3.3 volts. Significantly lower voltage may indicate the cell is damaged or near the end of its life.
2. Load Test: Apply a load to the battery and measure its voltage and current output using a load tester or a specialized battery analyzer.
3. Visual Inspection: Inspect the battery for signs of damage, such as swelling, leaks, or corrosion, which may indicate the battery needs replacement.
4. Capacity Test: Measure the battery's ability to hold a charge by performing a capacity test with a specialized battery analyzer.

Lithium Battery PACK Assembly

The assembly process for a lithium-ion battery typically involves the following steps:

1. Cells Paper Pasting
2. Cells Laser Welding
3. High Precision BMS Testing
4. Battery Pack Assembly
5. Battery Pack Aging
6. Battery Pack Comprehensive Testing

Frey New Energy - 3 Reasons that Prismatic LFP LiFePo4 ...

Frey New Energy – 3 reasons that Prismatic LFP lifepo4 lithium battery cell is the winning cell for battery packs of modern underground mine equipment.

Mining vehicle manufacturers are developing new, game-changing BEVS (Battery powered Electric Vehicles) powered by lithium-ion batteries as an alternative to diesel power. Given the high energy density of Li-ion batteries, they’re currently the most common and convenient battery for new BEV applications.

The quiet, low heat, and zero-emission of Li-ion battery quickly improves underground work environments and eliminates health hazards to workers. Not to mention they’re responsive, have fewer moving parts, and require less maintenance.

The Lithium-ion battery industry has expanded rapidly in the last 10 years. Because of this, we also see many accidents of lithium-ion battery explosions and issues associated with fighting big battery fires. According to OSHA/CPSC, 25,000 overheating or fire incidents involving more than 400 types of lithium battery-powered consumer products occurred over a five-year period.

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As the concern of safety becomes more obvious, some lithium-ion battery cells are claimed to be explosion-proof and fire resistant. It can be confusing and misleading if we don’t understand the different chemistries and types of lithium batteries.

This article will uncover the myth of their differences and provide a deep analysis from the aspects of safety, lifespan, and commercial maturity, so you will understand why we think Prismatic LFP LifePO4 Lithium battery is the winning chemistry for modern underground mine equipment.

What is a Lithium Ion Battery?

In a Li-ion battery, lithium ions travel back and forth between the anode and cathode during charge and discharge (negative electrode being anode, positive electrode being cathode). The ions move in an electrolyte and across a separator that sits between the two electrodes (Figure 1).

The sequence involves reduction/oxidation (redox) reactions specific to the particular chemistry of the cathode, and the chemical energy of these reactions is harnessed to store and discharge electrical energy from the positive and negative terminals of the battery.

Anode materials include:

Graphite (the most common type)

Hard Carbon

LTO (Lithium Titanate Oxide)

Cathode materials include:

LCO-Lithium Cobalt Oxide

NMC-Lithium Nickel Manganese Cobalt Oxide

LFP- Lithium Iron Phosphate

The choice of the cathode material will affect greatly the end battery properties such as safety, energy, life cycle, and cost.

The electrolytes include:

Liquid organic solvents

Gels

Polymers

Ionic liquids

Below, we made a comparison between the most common cathode materials that could be used in mine BEVs.

LCO-Lithium Cobalt Oxide

NMC-Lithium Nickel Manganese Cobalt Oxide

LFP- Lithium Iron Phosphate （LiFePO4）

LTO- Lithium Titanate LTO is anode, which can be combined with any cathode.

From the prospects of safety, life span, and cost, LFP battery is not doubt the winner among them all. It does have relatively low energy density. However, in the industrial application, the weight and space are not equally as demanding as, say, a passenger car. In reality, low energy density can turn to an advantage, it will require less counter weight in applications where counterweight is required.

Contact us to discuss your requirements of high-output lithium ion battery assembly line. Our experienced sales team can help you identify the options that best suit your needs.

Safety

Safety is always the #1 priority in the mine industry. One accident happens, it can cost businesses millions of dollars. The primary hazard from Li-ion batteries is a catastrophic event called thermal runaway in which the battery quickly and sometimes violently releases its stored electrochemical energy.

We’ve seen several severe incidents of car and airplane explosions due to li-ion battery thermal runaways. This is why the mining industry must use the battery that has the highest thermal stability and tested explosion proof; both the battery pack and the cell itself.

The key advantage of LFP as a cathode material lies in its chemical stability and the ability to withstand relatively high temperatures. The molecular structure absorbs and releases lithium ions without a large change in volume, and it’s resistant to the growth of defects from daily charge and discharge cycles.

The P-O bond in the lithium iron phosphate crystal is stable and difficult to decompose. Even at high temperature or overcharge, it will not collapse and heat up like lithium cobalt oxide nor form strong oxidizing substances.

In China, for lithium-ion battery to be able used in mine equipment in coal mining, it has to be approved by Mining Products Safety Approval and Certification Center (MA Center) in Beijing, a stress test of the li-ion battery cell and modules needs to be done. There are 23 test items for lithium-ion batteries.

Some of the extreme stress tests that can be related to real life battery abuse includes: nail penetration, baking with flame, external short circuit and over-charge.

During the some of the toughest tests, the LFP cell was smoking, no fire or burning occurred. In the baking with flame and external short circuit tests, LFP cell remains explosion-proof and fire-free.

In the overcharge stress test, high charging voltage several times higher than the rated discharge voltage was used, and it was found that there was still no explosion on the LFP battery. The safety of overcharge is extremely important, as it is one of the most common thermal runaways.

LFP batteries can be used safely in ambient temperatures up to 55°C (131°F). Even if it catches fire, it shoulders like coal, and needs oxygen to burn. On the other hand, the popular NCM battery burns violently like gunpowder, and requires no oxygen to be set aflame.

There are also differences in putting out the fire when your battery is burning. For LFP, normally water or foam can kill the fire. However, for NCM, it can get very complicated.

Frey New Energy shared some details of the nail penetration test they conducted to a 3.2V100Ah Cell. After the battery was fully charged, a steel nail was directly penetrating the center of the cell. With a speed of 40mm/S, the nail remained inside the cell. There was no fire or explosion.

Battery Life

Mine trucks and equipment are durable, built to last. They consume high power compared to passenger EVs. They need an equally durable and reliable power pack to match the nature of the equipment. That’s why it is wise to choose a battery pack that lasts long term and require few replacements in a very long period of time.

Current expectations on the lifetime for a battery in heavy‐duty vehicles is 6 years. However, for future generation batteries, the expectation is that they would last the lifetime of the vehicle. A defining factor in determining battery life is the particular cell chemistry used in the battery pack.

According the table, LTO has the best life span. However, due to its high cost and low energy density, it has not been widely used and hasn’t reached commercial maturity in mining industry. The cycle life of Lifepo4 is over 3,000 with 80% depth of discharge, while NCM only reaches 800. When the LFP battery is used with 50% depth of discharge, the cycle life can reach 4,000 times, and with 20% depth discharge, it can reach even 6,000 times.

In the mining industry, the cycle life can be up to 3,000 times. If the machines run 365 days a year, then it has a life span of 8.2 years. Most lithium-ion manufacturers give a material handling warranty of 5 years or 10,000 hours uptime. Some are giving an energy Amp hour of 2,000 x nominal capacity, for example, if a battery is rated 200ah, then it gives a warranty of 200×2000 =400KWH total power output for the entire life span. This is 4 times the lifespan of a traditional lead-acid battery. LFP chemistry is the winner again in lifespan.

Production Efficiency

The electric passenger cars take 67% of global EV li-ion battery market, with a small fraction of 16% for commercial vehicles. The mine equipment takes a small part among the 16%. Small quantity, customized mine equipment is built in small batches, unlike passenger EVs. Massive production of one battery model to fit thousands of vehicles? That doesn’t work for mine equipment.

Lithium batteries for mine equipment need to be custom-built. In the battery pack building process, it’s critical to choose the most ideal cell for the best efficiency, and we’ve concluded that the LFP chemistry is most ideal. There are many different shapes of LFP battery cells, most common being prismatic and cylindrical. It’s important to choose the right shape. Below is a comparison of advantages and drawbacks.

The prismatic battery has a large capacity from 3.2V50Ah to 3.2V200Ah. The cylindrical cell has a small capacity from 3.2V1.5Ah to 3.2V6Ah. Among the most common type of cylindrical cells is the 18650. The term 18650 comes from the IEC naming scheme for round cells based on their physical dimensions. The first two digits are its diameter in millimeters, while the last three digits are for its height in 1/10th millimeters.

But the question remains: why is it important to use large capacity cells?

Better consistency

We can explain this better with the “barrel theory”. Just like the capacity of a barrel is determined by the shortest wooden bars, the performance of the whole battery pack is determined not by the best performing cell, but by the worst. In lithium battery pack assembling, it is critical to choose the most consistent level cells.

The consistency of the battery pack is also related to the number of cells. The more cells, the worse the consistency and the worse the performance of the battery pack will be.

Easy Assembly

For example, to make an 80V500Ah lithium battery pack, using a lithium iron phosphate LFP 3.2V100Ah prismatic battery cell will only require 125 battery cells. Use 25 of 3.2V100Ah to make 80V100Ah, and then serial connect 5 of the 80V100Ah to make 80V500Ah. If you use LFP cylindrical battery 32650-6Ah batteries, you’re looking at 2,075 battery cells.

If you want to maintain the battery pack by checking each battery cell’s performance