Lifepo4 battery pack assembly. 10 Cantilever crane mechanism

Assembling a Lithium Iron Phosphate Marine House Bank

This article is part of a series dealing with building best-in-class lithium battery systems from bare cells, primarily for marine use, but a lot of this material finds relevance for low-voltage off-grid systems as well.

Here, we detail the hands-on process of building a lithium battery bank from individual single prismatic cells. There is more to it than just arranging and connecting the cells, because those can only be assembled into a battery after they share a common state of charge. They also need to be protected before anything can be done with the battery, which is the object of another article.

Before that, preliminary decisions also need to be made: how much capacity to install and what cells to source? What is the most suitable interconnection scheme to adopt?

A 200Ah DIY lithium battery back for a yacht, balanced and instrumented for cell voltages and temperature. A standard 12-pin plug connector provides the interface to the battery protection module. Cell clamping arrangements can be very simple and effective.

Buying cells and assembling the bank is not the beginning. Learning about lithium cells and understanding their properties and their risks is, before committing to building anything.

As it is an extensive topic in itself, the integration of a lithium battery on board is also dealt with separately.

Disclaimer

A good understanding of DC electrical systems is needed to build and commission a lithium battery installation. This article is aimed at guiding the process, but it is not a simple blind recipe for anyone to follow.

The information provided here is hopefully thorough and extensive. It reflects the knowledge I have accumulated building some of these systems. There is no guarantee that it will not change or grow over time. It is certainly not sufficient or intended to turn a novice into an electrical engineer either. You are welcome to use it to build a system, but at your own risk and responsibility.

How Much Capacity?

Generally speaking, a LiFePO4 bank will offer about twice the usable capacity of equivalent deep-cycle lead-acid cells in good condition, and much more when such lead-acid cells have deteriorated. This can provide a rough guideline when considering the purchase of lithium cells. In practice, it only suggests the maximum capacity that should be considered as a starting point: no more than 50% of the lead-acid capacity.

In the traditional lead-acid way of thinking, more capacity meant smaller cycles and longer life and a justification was found there: the situation is almost the exact opposite with Li-ion batteries

Many lithium banks installed on yachts nowadays are in fact not only much larger than they need to be, but also much larger than they should be.

The oversize bank approach can in fact deliver less value: there is nothing suggesting that a bank twice as large will last twice as long: it will more than likely just result in twice as many old buggered cells at the same point down the track if not earlier. The first consequence of installing an oversize battery bank, especially when sustained charging is involved as with solar panels, is that the bank remains at a higher state of charge much longer, if not most of the time. This is very detrimental to its ageing for reasons that were developed earlier. Lithium cells like cycling because it means they don’t spend any amount of time near full; alternatively, they can sit happily half-discharged, or even lower, for years.

Invest in energy efficiency or charging capacity, not in unnecessary storage

The bank needs to be large enough to provide the capacity needed between recharges, but beyond that, all what comes out needs to go back in and the size of the battery makes no difference there. Money is best invested in energy efficiency on board and charging capacity than storage.

The question therefore revolves around the cycle duration that must be accommodated. A yacht spending all its time in the tropics with considerable solar supply available on a daily basis doesn’t technically need to store much more than its overnight consumption, strictly speaking. The ability to accommodate a 2-day or 3-day cycle may be valuable however, but this calls for adapting the management of the battery to suit. Consumption can also be reduced in adverse conditions, extending cycle duration and this is a sensible way of looking at the matter, compared to calculating everything on maxima and worst-cases.

In practice, lithium banks of about 200Ah are easily capable of supporting yachts with an electric refrigeration system and auxiliary loads in the mid-latitudes and it is very difficult to present a valid case for installing more than 300-400Ah on a sensibly outfitted pleasure craft. Some, however, are fitted out and operated as if they were permanently tied to the power grid.

Some of the installations I built and commissioned included a provision for expansion by adding an extra set of cells later if needed, in order to alleviate the owner’s concerns. None of them were expanded afterwards

While a lithium battery bank can easily be expanded by adding more cells later if needed, unneeded capacity cannot be returned for a refund. Best long-term value is achieved when both the installed capacity and the management of the installation are correct and adequate.

Sourcing Cells

Those are all common cells on the market today: the CALB SE-series in blue and CALB CA-series in grey (now identical other than for the casing). Sinopoly cells are black and Winston cells are yellow.

There are many manufacturers of LiFePO4 prismatic cells, mostly located in China, but the only well-known ones are those imported and available in the Western countries. Some smaller players like Hipower and Thundersky have disappeared. Some of the oldest names in the game today are Sinopoly, CALB (China Aviation Lithium Battery) and Winston, the latter having had a troubled history in recent years. Short of having a significant amount of time and access to a lab, it is very difficult to differentiate these products from a quality point of view.

Sinopoly and CALB operate their own research and development labs. CALB in particular has also established a very strong reputation for product quality control with each cell being measured and labelled with its actual capacity before being shipped. Yet, issues with CALB cells are not unknown to occur. Winston has been making reliable and long lasting cells for a very long time. In spite of being virtually unknown, Lishen also makes very good cells, which were selected by a large customer in Switzerland following lab tests, ahead of the better known brands.

While it is often possible to source unusually cheap cells with obscure brand names, such bargains might not represent long-term value. The ageing behaviour of the cells is extremely dependent on the quality of its manufacture and trade secrets associated with electrolyte composition and, in this regard, even the best known brands are not all equal.

The process begins with combining the raw materials of which the lithium cells are composed

Lithium cell composition

As is known, lithium ion cells have two electrodes, namely, a cathode (positively charged, consisting of cathode material such as NMC, LFP, etc.) and an anode (negatively charged, consisting of anode material such as graphite or carbon).

Added to these is a central separator. a layer of thin material composed, as a rule, of a plastic or ceramic polymer that acts as an insulator between the two electrodes. Finally, there is an electrolyte. an organic liquid containing lithium salts which fills the inner volume of the cell and wets the electrodes, thereby joining anode and cathode.

But how are the anode and cathode sheets made?

There are essentially three steps to follow:

First of all, the raw materials. in the form of powders that will be used in the lithium-ion cell, are combined in a large mixer using different methods: dry, in liquid form, with solvents or in water.

The resulting chemical compounds must then be added with components (binders or other substances) to obtain a uniform layer that will be applied on the metal electrodes through the coating process. This operation is very similar to the screen-printing process, where a sheet of aluminium or copper is passed under a roller press and the resulting mixture is spread out perfectly so that the cell is uniform and high-performing.

Once the coating process has been completed, the drying phase begins in an oven that can reach 150 °C. This phase includes maintaining a steady temperature and humidity level and is relatively comparable to other production processes, such as those used in the ceramics industry.

Example of mixing process

Example of coating process

Additional details on this phase?

Week 10 of Battery Weekly 2022, our weekly report on the lithium ion battery industry, featured a discussion on precisely this subject

Lithium cell assembly: the different methods used

Once the anode and cathode sheets have been prepared, they are ready to be joined by adding the separator. The real assembly phase of the cells (the backbone of a lithium battery) then commences, and can be executed using a variety of composition techniques:

Stacking of individual sheets

This solution involves cutting the anode, cathode and separator sheets individually, using a robotic arm for each, and then stacking them on top of each other until the entire lithium cell is created.

The other two construction techniques, however, result in a single sheet that may be rolled onto itself in a variety of ways.

Z-folding process

The folding method known as Z-folding sees the anodes and cathodes cut into sheets, while the separator remains continuous. In this case, the anode and cathode sheets are first cut and then inserted into the separator, a continuous roll which keeps the two electrodes separate by means of a Z-folding process.

Rolling process

The rolling process consists of rolling four sheets of material together, first stacked on top of each other (anode sheet separator cathode sheet separator), and then rolled onto a cylindrical or ovoid base to give the typical shape of the prismatic or cylindrical cell case.

As has already been illustrated, the assembly methods may be different, but the battery cell composition remains the same. In the images of the various assembly processes can be seen how the anode has a basic brown colour, as the coating is deposited on a thin layer of copper. Then comes the plastic or ceramic separator, and finally, the cathode, which is grey in colour, since it is deposited on a layer of aluminium.

What are the pros and cons of the different cell assembly methods?

At the time of writing, no one technology prevails over the others in lithium ion cell production. Each manufacturer has a favoured methodology and each will argue the merits of its choice according to the end use of the lithium battery taken as a whole.

What can be said, however, is that the stacking method makes good use of the space on a rectangular cell (pouch or prismatic). This is because, positioned in this way, the sheets manage to fill all spaces perfectly, thus increasing the active area. Nevertheless, the stacking method carries two types of risk:

  • if the sheets are slightly out of alignment, the separator in particular may be unable to avoid contact at the edges of the two electrodes, leading to short circuits;
  • even if a laser is used, sheet cutting might still result in imperfections or could damage the edges, all of which leads to yet another difficult-to-control factor in cell quality.

In contrast, rolling or folding systems give a better guarantee of separation between components. since there are no gaps in the separator. The disadvantage, in this case, lies at the bending or curving point, which is subjected to greater mechanical stress and thus runs a greater risk of rupture, causing the two electrodes to short-circuit.

Furthermore, in the rolling method, the end result is a more or less oval-shaped roll, meaning that the corners of the rectangular cell contain no material and hence that less use will be made of the inner volume. For this very reason, even large cells are often made by placing several smaller rolls parallel to each other inside the cell.

What does the structure of a lithium cell look like after assembly?

The above image gives a clear example of the internal lithium battery cell composition, before it is placed into its containment case and used in modules to create the complete lithium battery pack. In this specific case, one is dealing with a prismatic cell, where two “small packs” are held in place by a central ribbon (yellow).

In the centre can be seen the separator (white), while to the right and left are the cathode (copper) and anode (aluminium), which will then be connected to the external terminals of the cell by means of ultrasonic welding.

Once assembled, the cell is placed in a case and filled with the electrolyte

Once assembled, the various materials of lithium cell composition are placed in a containment case. with the two outer positive and negative electrodes welded to the inner tabs and a central filler hole where the electrolyte will be injected. It will be recalled that the electrolyte has the basic function of passing the lithium ions from cathode to anode.

The animation shows the various stages of cell filling. an operation that at first glance seems simple, but which in fact is a particularly delicate and costly process requiring numerous steps. A liquid containing lithium salts is inserted into the central hole. The stack gradually absorbs it by means of capillary action. Where liquid is actually needed is in the middle of the cell, between the two electrodes and the separator.

Filling is an extremely slow process. since, in order to allow the liquid to be absorbed without leaking, the cell needs to be filled at various times. Suffice to say that the final filling is done after an aging period of several days. Prior to the final sealing, a filling level control phase is carried out by weighing the cell. This step is essential and absolutely necessary, as once the cell is completely sealed the hole will be closed and no longer accessible.

Lithium cell assembly is only one piece of the puzzle

Correct assembly of the cells that make up a lithium battery, whether such cells are prismatic, cylindrical or of the pouch type, is therefore an extremely complex operation. requiring long machinery set-ups as well as the utmost precision at every stage, an essential element to ensure safety, quality and reliability over time. Because of the regular and stringent inspections for contaminants and the need for uninterrupted operations in cleanrooms, this process requires huge investments as well as expansive facilities.

After the choice of the most suitable lithium chemistry, correct cell assembly is without doubt the first step (of a long series) required to achieve complete efficiency of a lithium battery. It is a complex chain of actions that ranges from the creation of the module to the implementation of state-of-the-art control electronics with advanced BMS, and culminating in the development of battery packs with increasingly advanced architectures.

Each electrical application has its own unique specifications, and in order to ensure proper operation it is crucial to strike the right balance between all of these components which, like pieces of a jigsaw puzzle, must be expertly positioned to create the product’s identity, something that can only be ensured by a skilled and consolidated manufacturer.

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Notes:

Source Video 1-2-3: Video “Cell stacking processes for lithium-ion cells” from TUM School of Engineering and Design YouTube Channel https://youtu.be/ESvVLEwXYwM Source Video 4: Video “Electrolyte filling of a lithium-ion cell” from TUM School of Engineering and Design YouTube Channel https://youtu.be/ceUSPNzxwls Source Fig. 1: image taken from video “How is made a lithium-ion battery” from Lithium Battery Company YouTube Channel https://youtu.be/UHZg5-uk1-k

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Equivalent Circuit Model and Mathematical Model Based on 3D Geometry

According to the case that nickel plates are widely used in the assembly of battery packs, the 3D geometry model of the parallel module is constructed. Figure 1A shows a common type of 4p parallel module connected by nickel plates. The parallel module is composed of positive and negative nickel plates and four cylindrical cells. The positive and negative collectors of the cell are connected to the positive and negative nickel plates, respectively, achieving a parallel configuration instead of connecting the positive collectors or negative collectors of adjacent cells sequentially through wires. As shown in Figure 1A, the positive and negative nickel plates of the parallel module are cuboids, and different surfaces of nickel plates can be selected as the contact surface for series assembly. Therefore, there are two typical series assembly methods for parallel modules: for simplicity, the series assembly method that parallel modules connected through the short surface is named S-Assembly (i.e., Figure 1B), and the series assembly method that parallel modules connected through the long surface is named L-Assembly (i.e., Figure 1C).

FIGURE 1. (A) 3D geometry model of the 4p parallel module. (B) 3D geometry model of S-Assembly. (C) 3D geometry model of L-Assembly. (D) 3D geometry model of the 5s4p battery pack.

First, the performance difference between S-Assembly and L-Assembly is analyzed based on the ECM. The Thevenin model (Saxena et al., 2019; Zhou et al., 2019; Feng et al., 2021), shown in Figure 2A, is selected as the ECM of the cell due to its relative simplicity, ease of parameterization, and real-time feasibility. The charging and discharging processes of a cell model can be expressed as

where U, OCV, R0, RP, CP, I, and τ are the terminal voltage, open-circuit voltage, Ohmic internal resistance, polarization resistance, polarization capacitance, charge and discharge current, and time constant of the cell, respectively. The series resistance R0 is used to represent the sum of the resistances of various battery components and model the ohm polarization process for fast dynamics (Zhu et al., 2019). The parallel resistor–capacitor network RPCP is used to describe the charge-transfer process and diffusion process during the charging/discharging duration. In the view of the electrochemical mechanism, the 1s impedance in the time domain is usually considered as the R0, which includes the pure Ohmic resistance and partial inductance resistance, partial film resistance, partial charge-transfer resistance, and partial diffusion resistance (Ruan et al., 2021). When the cell is charged or discharged at constant current, the internal resistance R can be expressed as

FIGURE 2. (A) Equivalent circuit model of the cell. (B) Equivalent circuit model of S-Assembly. (C) Equivalent circuit model of L-Assembly. (D) Equivalent circuit model of the 5s4p battery pack.

Then, the ECMs with S-Assembly and L-Assembly are established based on the ECM of the cell, as shown in Figure 2B and Figure 2C, respectively. Rlink is the connector resistance between adjacent cells in the parallel module, and Rinter is the connector resistance between adjacent parallel modules. The current path divides the nickel plate into several “small nickel plates”, which are the connector resistances. The current of each cell of the parallel module for S-Assembly can be expressed by the following equations:

U p m = U 1 − ( 3 I 1 2 I 2 I 3 ) R l i n k U p m = U 2 − ( 2 I 1 3 I 2 2 I 3 I 4 ) R l i n k U p m = U 3 − ( I 1 2 I 2 3 I 3 2 I 4 ) R l i n k U p m = U 4 − ( I 2 2 I 3 3 I 4 ) R l i n k U i = O C V i − I i R i I = ∑ i = 1.4 I i ( 3 )

where Upm is the terminal voltage of the parallel module; I is the discharge current of the battery pack; and Ui, OCVi, Ii, and Ri are the terminal voltage, open-circuit voltage, current, and internal resistance of the ith cell, respectively. The connector resistance can be obtained by the following equation:

where ρ, L, and S are the conductor material resistivity, conductor length, and conductor cross-sectional area, respectively. Since the Ohmic polarization occurs instantaneously, the cell current distribution at the beginning of discharge is affected by the terminal voltage of the battery pack, the connector resistance, and the Ohmic internal resistance of the cell. When the parameters between cells are consistent, the matrix equation of the initial cell current distribution of the parallel module for S-Assembly is obtained according to Eq. 3, that is,

Modeling, Verification, and Simulation

Based on the above mathematical model, the COMSOL simulation is carried out to discuss the cell current distribution of packs with S-Assembly and L-Assembly and further study the influence of connector resistance and MCP on the performance of series–parallel battery packs assembled by nickel plates.

Cell Modeling and Verification

The cell ECM built into COMSOL is consistent with that shown in Figure 2A. In this paper, the new lithium-ion 21700-format cell LGM505000mAh is ideally suited owing to their very-high-volume production recently. The detailed parameters are shown in Table 1. The nominal capacity of the cell is measured via a constant current discharge with a constant C/3 until the cut-off voltage (2.7 V).

TABLE 1. Detailed parameters of LGM505000mAh.

The critical parameters (OCV, R0, RP, CP) are related to SOC. To obtain the parameters, pulse power tests are carried out with 21700-format battery cells on a test bench. In a pulse test, there are three pairs of 60 s charging and discharging pulses at increasing magnitudes and scaled relative to the different maximum cell current rates (0.2, 0.5, 1C), followed by a 30 min rest at the ambient temperature of 25°C. Then, according to Eq. 1, the parameters are adjusted with the pattern search optimization algorithm in the program Matlab, such as the Recursive Least Squares algorithm. over, the identified model parameters at different SOCs are shown in Figure 3A. It is obvious that the R0, RP, and CP change little with SoC, except for extremely low SoC levels. Therefore, for the above theoretical calculation, the assumptions that the parameters can be seen as constant values are validated. The cell parameters are listed in Table 2. In addition, the OCV-SoC curve of the cell ECM is fitted by the dataset obtained from the discharging and charging at approximately C/25. The dataset contains 768 sets of data, as shown in Figure 3B.

FIGURE 3. (A) Identified model parameters at different SOCs. (B) OCV-SoC curve measured by experiments.

TABLE 2. Parameters of the cell ECM.

The performance of the cell ECM is verified with a constant-current (CC) discharge. The CC discharge test is performed on the fully charged cell with 0.3 and 1C at an ambient temperature of 25°C, as shown in Figure 4. It can be seen that the simulated results are in good agreement with the experimental data. Finally, the ECM of the battery pack is built by setting the nodes to determine the connection relationship of the cells.

FIGURE 4. (A) Simulated and experimental results of cell terminal voltage and simulation errors at 0.3C. (B) Simulated and experimental results of cell terminal voltage and simulation errors at 1C.

COMSOL Model and Simulation Procedures

First, the 3D geometry models of the battery pack shown in Figure 1B, Figure 1C, and Figure 1D are established by using COMSOL Multiphysics, respectively. The geometry parameters of the cell, positive and negative collectors, adopt the geometry size of the 21700 lithium battery. The distance between adjacent cells in the battery pack is 0.1 d, where d is the diameter of a cylindrical cell. The thickness of a nickel plate is 0.1 mm. The specific parameters of the 3D geometry model are shown in Table 3. Meanwhile, the positive and negative collector materials of the cell are set to aluminum and copper, respectively.

TABLE 3. Geometry parameters of the 3D model.

Second, based on the above cell ECM, some battery circuit modules of COMSOL are used to build the ECMs of the battery pack shown in Figure 1B, Figure 1C, and Figure 1D, such as the current source module and nickel plates. All nickel plates are set as domains for the current module, and they are used to simulate the current distribution and flow in the nickel plates. Meanwhile, all the circular contact surfaces of the nickel plate and cell electrode collector are set as circuit terminals to realize the electrical connection of the battery pack.

Results and Discussion

Based on the above results, we analyze the causes of the performance differences between S-Assembly and L-Assembly and obtain the guidelines for the series assembly of parallel modules in this section. Then, we discuss the influences of MCP, connector resistance, and current rate on the performance of a series–parallel battery pack assembled by nickel plates.

The Influence of Two Typical Series Assembly Methods

The 1°C discharge simulation results of S-Assembly and L-Assembly are shown in Figure 6. There are differences in the cell current distribution between different assembly methods, and the cell current consistency of L-Assembly is obviously better than that of S-Assembly. The current of each cell in L-Assembly tends to be equal, which is the same as the mathematical model (Eq. 9) in the Equivalent Circuit Model and the Mathematical Model Based on 3D Geometry. It can be seen from the 3D geometry model of L-Assembly that the distance between each cell and the assembly contact surface is equal, which means that the equivalent resistance of each parallel branch is the same. However, there are differences in the current of cells in S-Assembly. The discharge currents of cells 1, 4, 5, and 8 are larger than those of other cells. The phenomenon is consistent with the conclusions of other publications; that is, the cell closer to the module collector has the higher current. According to the 3D geometry model of S-Assembly shown in Figure 1B, the positions of the assembly contact surfaces can be regarded as the Z-configuration. The cell closer to the assembly contact surface has the higher current, which is due to the equivalent resistance of the parallel branch the cell located in is smaller. In order to prove the validity of the mathematical model for S-Assembly, the calculation results obtained by Eq. 6 are compared with the simulation results. According to Eq. 4, the value of connector resistance is 2.63 mΩ; since the resistivity of nickel is 6.84 × 10 − 8 Ω ⋅ m. the length, width, and thickness are 23.1, 6, 0.1 mm, respectively. The cell’s Ohmic internal resistance is 20 mΩ, so the value of θ in Eq. 6 is 0.1315. Table 4 shows the simulation and calculation results of the initial current rate of cells of the parallel module for S-Assembly. It can be seen that the calculated values are relatively consistent with the simulated values, which proves the validity of Eq. 5 and Eq. 6.

FIGURE 6. (A) Cell current distribution of two assembly methods. (B) Cell voltage distribution of two assembly methods. (C) Pack voltage distribution of two assembly methods.

TABLE 4. Simulation and calculation values of initial cell current rate of the parallel module for S-Assembly.

lifepo4, battery, pack, assembly, cantilever, crane

As shown in Figure 6B, the cell current consistency does not cause a significant difference in the cell terminal voltage. This means that the uneven cell current distribution is difficult to be reflected by the cell terminal voltage in practical applications. However, differences in the assembly method can lead to the different terminal voltage of the battery pack, and the terminal voltage of the battery pack of L-Assembly is significantly higher than that of S-Assembly. It is related to the geometry of the nickel plate in the series–parallel battery pack and the current path in the nickel plate. Obviously, the slender nickel plate in S-Assembly has a longer distance for the current path and a smaller cross-sectional area perpendicular to the current direction, which means that the equivalent resistance of S-Assembly is larger than that of L-Assembly. Therefore, the increase of voltage loss results in a low terminal voltage.

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Therefore, whether in terms of cell current consistency or pack terminal voltage, the series assembly method that parallel modules connected through the long surface (L-Assembly) performs better. In summary, the distance between each cell and the assembly contact surface should be equal when the parallel modules connected by nickel plates are assembled in series so that the equivalent resistance of each parallel branch is the same. Meanwhile, the equivalent resistance of parallel modules should be reduced as much as possible to reduce the voltage loss of the battery pack.

Influence of Module Collector Position

The 1°C discharge simulation results of the 5s4p battery pack are shown in Figure 7. The left part is the simulation result of the Z-configuration, and the right part is that of the ladder configuration. Obviously, the ladder and Z-configuration have the same effect on the distributions of cell current, voltage, and SoC and the terminal voltage of the battery pack. There is a new discovery in this paper that the cell currents of the non-edge parallel module of the series–parallel battery pack are consistent, which means that the non-edge parallel module part can be replaced with the SCM connection topology.

Function Module Introduction

3.1 Cleaning Gluing Station

3.1.1 Equipment description:

Introduction of cleaning and gluing station: 1. After the worker places the battery cell on the feeding conveyor belt, the equipment can automatically complete the cleaning and gluing; 2. Equipment beat: 12PPM;

3.1.2 Equipment parameters:

0.02g,The error ratio does not exceed ±5%

point-to-point/continuous line segment

Fangtong welding mechanism、countertop soldering

Sheet metal fully enclosed structure,

3.2 Stacking Rotary Tables

3.2.1 Description of the Action Flow:

Action process: The stacking robot unloads and unloads materials from the gluing equipment conveyor line, and performs stacking operations in the serial-parallel sequence of the module recipes. This stacking method can flexibly accommodate module combinations with different recipes in series-parallel sequences. The stacking sequence is from bottom to top, and the cells and insulating plates are alternated, from the 1st hand cell to the 1st hand insulating plate, and then to the last hand 1 cell. During the stacking process, a downward pressing and beating mechanism is simultaneously pre-pressed and fixed.

The gripper is controlled by the robot to control the gripping mechanism, and the gripper is designed with photoelectric induction cells in place. The module stacking platform adopts a fixed-slope dual-station design. Each station contains dual clamps, which can place two cells at the same time. When the A station is stacking, the B station synchronously performs the moving work before extrusion, and the double station alternates, so as to improve the efficiency of stacking and moving.

3.2.2 Changeover Strategy Explained:

Change the cell gripper: choose a long-stroke clamping cylinder, which can be automatically compatible with different types of cells when changing;

Changing the gripper of the insulating plate: the vacuum suction cup assembly is installed on the aluminum profile, and the distance between the suction cups can be adjusted manually according to the width of the insulating plate when changing the model.

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Electrical program: According to the serial-parallel stacking sequence of compatible modules, the robot performs the stacking operation according to the preset robot stacking sequence program. Before changing the model, the stacking program of the model-changing product is transferred.

3.2.3 Changeover Strategy Explained:

3.3 Function module introduction

3.3.1 Extrusion station: Double-row module process

The handling robot transports the single-row stacks 1 and 2 respectively from the stacking turntable to the extrusion table sliding table, and the sliding table slides to the manual extrusion position; 2. Manually install the middle partition board (manual cleaning and gluing), end insulation board (manual cleaning and gluing), and end plates (manual cleaning and gluing), and then press the button to install the steel cable ties.

3.3.2 Extrusion station:

3.3.3 Extrusion station: Equipment flow description:

Place the glued cells by the handling robot to the discharge position of the sliding table, and the sliding table automatically slides to the manual extrusion position;

Manually attach both ends to the end plate, install the side rails, first press the width direction extrusion button to make the length direction of the module horizontal; then press the extrusion start button, the cylinder drives the top plate to extrude the cell, When it reaches the set length, it stops, inserts the steel belt, punches the plastic steel belt, and rives the screw;

After the installation is completed, press the open button, squeeze the cylinder to retract, and then press the slide button, the installed module slides to the discharge position again, and the robot grabs it to the stationary trolley.

3.3.4 Extrusion station: Changeover Strategy Explained:

Extrusion Tooling Changeover Instructions

Change of handling gripper: Servo screw clamping mechanism is adopted, and the electrical program can be switched with one key during model change;

Extrusion table change: choose a long-stroke clamping cylinder, which can be automatically compatible with different types of batteries when changing;

Robot program: According to the size of the compatible module, the robot will follow the preset robot handling program. Before changing the model, transfer the handling program of the replacement product.

3.4 Introduction of safety fence:

The design, manufacture and control of the safety fence comply with the relevant national regulations on production safety to ensure the safety of the production process.

Protective fences, fences, safety nets and other facilities are set up in places where human or machine damage may occur, and necessary interlocking protection is carried out. The safety door lock should be interlocked with the system. The safety door is self-locking and cannot be opened when the production line is working.

Entering the security door operation process: apply for entry. the robot and other equipment are parked in a safe position. the security door is opened. enter the security door.

Operation process for resuming production: go out of the security door – confirm that there is no one in the equipment area – close the security door, enter the recovery password, and the security door is self-locking – the equipment is operating normally.

3.5 Insulation withstand voltage test station:

The insulation test before welding is conducted by pressing all probes through the overall test mechanism, and then switching between the cell and the cell through the relay. Insulation test between shell and shell; Test procedure: all positive poles in series, all negative poles in series after the insulation test between the two, and then all positive. Insulation test between pole series and housing, insulation test between all negative pole series and housing.

3.6 Insulation withstand voltage test station:detailed description of the equipment:

Operation process: the tray is lifted and positioned, the shell probe is pressed to the end plate or the side plate, and the positive probe relays of all cells are closed, so there is insulation between the positive electrode of the cell and the shell; the positive electrode of all cells is Divide into two groups, an odd-numbered group and an even-numbered group, and test the insulation between the positive electrodes.

Model replacement strategy: According to the arrangement of the cells corresponding to the pallet arrangement, establish a coordinate system for the coordinates of the formula skipping step. Before changing the model, call up the test jump coordinate program, carry out the first piece test OK, and proceed to the production mode after the model changing.

.10.2 Cantilever crane mechanism:

3.11 Tray introduction

3.11.1 Pallet Introduction: Changeover Strategy Explained

Pallet replacement strategy description:

Width direction type change: manually change the position of the side stop (the bottom plate of the tray will be prefabricated with different types of holes);

Change in length direction: manually replace the position of the card slot of the front block directly.

3.12 FPC welding workstation:

The equipment is mainly composed of five parts: three-dimensional table, galvanometer, CCD and light source, rack hood, and rangefinder;

This equipment is used for offline manual welding of FPC boards. FPC and bar positioning tooling are provided by customers.

Industry Application

Lithium battery module fully automatic assembly line is mainly used in the production of new energy lithium battery modules, Prismatic battery modules, energy storage battery modules, power battery modules and pack welding assembly, etc.

Unlock Efficiency and Boost Productivity

Are you tired of the time-consuming and labor-intensive process of assembling battery packs? Look no further than our cutting-edge Battery Pack Assembly Line. Designed to revolutionize your production process, this fully automatic assembly line will streamline your operations, saving you valuable time and resources.

With our Battery Pack Assembly Line, you can say goodbye to tedious manual labor and hello to increased efficiency. By automating the assembly process, our state-of-the-art machinery eliminates human error, ensuring consistent and precise results. Experience a significant reduction in production time while maintaining the highest standards of quality.

Shipping and Returns

We ship the majority of our orders by the next business day. Lithium batteries may take up to two business days to process to accommodate inspection and logging into our system.

Our shipping rates are based on the weight of all ordered products plus estimated weight of packaging. We make every effort to forecast an accurate shipping cost, but cannot be 100% certain in all cases. Please contact us at sales@higherwire.com with any questions prior to purchase.

We have a 30-day return policy, which means you have 30 days after receiving your item to request a return.

To be eligible for a return, your item must be in the same condition that you received it, unused, and in its original packaging. You’ll also need the receipt or proof of purchase.

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