Guidelines for Battery Pack Design and Selection

Designing a battery pack presents its fair share of challenges, particularly in understanding the technical aspects associated with batteries. In this discussion, we aim to simplify the concepts as much as possible, using straightforward formulas to gain a fundamental grasp of battery design and application.

To begin, it's crucial to recognize that a lithium-ion battery module system comprises various interconnected subsystems, each essential for sustaining the battery pack's longevity. The number of cells within the system may vary depending on the application,Battery recycling machine but all battery packs must connect these cells in different configurations to attain the required voltage and power. To secure and link the cells, a robust mechanical structure is necessary, enveloping them securely.

Contained within this encapsulated structure is the Battery Management System (BMS), a vital electronic controller responsible for detecting and overseeing all battery functions. The BMS can consist of separate electronic components mounted on individual cells or modules to monitor temperature and voltage, often incorporating a Voltage Temperature Tester (VTM). Additionally, a thermal management system, divided into passive and active solutions, is required.cylindrical battery pack mahcine Passive solutions typically rely on the encapsulated body shell to regulate temperature, while active solutions employ liquid or air as mediums to maintain optimal temperature within the battery pack. Of course, the system also comprises electronic components, such as switches controlling current flow and wires. All these elements work harmoniously to form a comprehensive battery pack system that ensures the battery's proper operation while enhancing electrical performance, safety, and lifespan.

Considering that extensive research has been conducted to estimate battery manufacturing costs,cell stacking machine we'll briefly address the percentage of the total cost allocated to each battery component.

In a battery pack for plug-in hybrid electric vehicles or pure electric vehicles, cells account for 60% to 70% of the total battery pack cost, in contrast to larger power packs found in electric vehicles or plug-in hybrid electric vehicles.

Smaller energy battery pack cells contribute a much smaller proportion to the overall battery pack cost. For large energy storage systems, the peripheral hardware portion of the cell represents a significant share of the total cost.

Now that we have an essential grasp of the cost breakdown in a battery pack system, the next step is understanding the application of various battery types in different scenarios.

Batteries, as energy storage and supply devices, are primarily categorized into two main types: power-type and energy-type batteries. Power-type batteries primarily serve to provide short-term power for accelerating automobiles, storing less energy, and are unsuitable for prolonged energy supply. They typically exhibit a lower discharge rate, designed for periods lasting at least an hour. Energy-based batteries, on the other hand, are commonly employed in pure electric vehicles to provide extended driving ranges. In grid applications, battery systems serve as backup power sources, necessitating the provision of continuous energy over several hours. There is also a third battery type, which, although less frequently discussed, is referred to as a "balanced battery." These batteries are used in plug-in hybrid electric vehicles and must fulfill both power and energy requirements, depending on their operational mode.

It's important to note that factors such as high temperature, low temperature, and others can lead to lithium-ion battery capacity degradation and increased internal resistance, consequently affecting the battery's actual service life. Although lithium-ion batteries do not exhibit memory effects like nickel-based batteries, sustained impedance growth can result in irreversible capacity degradation and eventual failure.

Lithium-ion batteries are also subject to self-discharge during storage, which can be categorized into two types: permanent self-discharge and temporary self-discharge. Permanent self-discharge results in a permanent loss of battery capacity, often due to an increase in internal impedance during storage. Temporary capacity loss involves capacity reduction during storage, but it can be restored after a discharge cycle. Different battery systems exhibit distinct self-discharge profiles.

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