Like primary batteries, Keheng’s rechargeable lithium-ion batteries work by discharging to power devices and can be recharged for repeated use. Please refer to this blog for a comprehensive understanding of the differences between SLA (Sealed Lead Acid) batteries and lithium batteries. We will delve into lithium batteries’ types, configurations, and practical applications and how to optimize battery design to suit specific use cases.
Lithium Battery Form Factors
You will first encounter individual cells and circuit boards when examining lithium battery packs. Lithium batteries commonly come in three types of cells: cylindrical, prismatic, and pouch cells. The cells discussed in this article are all Lithium Iron Phosphate (LiFePO4) cells with a nominal voltage of 3.2 volts (V).
Cylindrical Lithium Batteries
Inspired by traditional household batteries like AA batteries, cylindrical cells have been used since the mid-1990s. These cells come in varying widths and lengths, offering different amp-hour ratings, and can be categorized as either energy-type or power-type cells. Cylindrical cells are particularly well-suited for applications requiring compact Ah batteries, including power tools, drones, children’s toys, and medical devices, where space and weight are critical factors influencing overall performance.
Prismatic Lithium Batteries
Considering that most battery compartments are designed to be square, prismatic cells are a natural choice. You’ll often find prismatic cells in laptops, where they can provide greater capacity in a compact footprint. Prismatic cells come in both power and energy types and can be sized to match sealed lead-acid batteries. While they are more significant than cylindrical cells, prismatic cells can store more amp-hours due to the increased volume of lithium, making them ideal for larger battery pack configurations and single-cell setups. Consequently, they are often chosen for energy storage solutions.
Lithium Polymer Pouch Batteries
Keheng’s Hyper Sport Pro series of powersports batteries use pouch cells. As the name implies, pouch cells are packaged in aluminum foil and contain lithium iron phosphate polymer internally, with tabs extending from both ends. This design maximizes volumetric energy density and can be directly integrated into devices without additional cell casing protection. Due to their unique construction and dimensions, lithium polymer pouch cells offer a higher power density than other battery types.
Types of Lithium Batteries
In addition to the form factor of lithium batteries, it is crucial to determine whether you need a lithium power-type battery or a lithium energy-type battery. Power-type batteries are specifically designed for high power output, while energy-type batteries focus on providing high energy. But what is the difference between power-type batteries and energy-type batteries?
What is the Difference Between Power Cells and Energy Cells?
It is important to note that all types of batteries undergo charge and discharge cycles, but the depth of discharge and rate vary (refer to battery C-rate (a measure of charge/discharge rate)). Power-type batteries can deliver high currents intermittently for short periods and are suitable for high-rate applications, starting scenarios, or power tools requiring high loads and torque. In contrast, energy-type batteries are designed to provide a stable, continuous current over a more extended period.
Understanding Lithium Battery Configuration for Electric Applications
Due to their excellent cycle life, lithium batteries are particularly well-suited for cycling applications, such as scooters and e-bikes. While all lithium batteries are suitable for cycling, the duration of these cycles can vary significantly. For example, power tools typically run for about an hour before needing a recharge, whereas scooters must provide longer run times to meet user needs.
Configuring Lithium Battery Packs
The first step in building a lithium battery is selecting the type that best suits your needs. Next, determine the Ampere-hours (AH) and voltage required for your specific application. It is also crucial to evaluate the current needs for optimal performance.
For example, if you choose a 25 AH 3.2 V prismatic cell and aim to create a 125 AH 12.8 V battery, the configuration would be a 4S5P setup. This means you would organize four main battery packs, each containing five cells arranged in parallel (5P), and then connect these four packs in series (4S), totaling 20 cells. Parallel connections are used to increase amp-hour capacity, while series connections are used to improve the overall voltage. Understanding how to connect batteries in series or parallel to achieve the desired performance is essential.
The diversity of lithium battery form factors arises from two primary considerations. First, different battery designs necessitate varying size, shape, and flexibility levels. Second, for flexibility in terms of capacity and voltage, one might opt to use multiple cylindrical cells to configure a 24 AH battery instead of fewer prismatic cells. Conversely, one might choose prismatic cells over cylindrical cells.
Moreover, the intended application plays a crucial role in the selection process. For example, while lithium energy cells can be used to make starter batteries, it would be wiser to select power cells for this application as they offer superior power delivery. Like traditional lead-acid batteries, lithium’s lifespan will be reduced if not used for its designated application—cycling, starting, or high discharge rate.
Keheng’s PSL-FP series of lithium batteries offers both power and energy options, allowing you to customize your battery pack to meet the demands of high-capacity, high-discharge rate, or deep-cycle applications. Additionally, we offer both prismatic and cylindrical cells for further customization possibilities.
Therefore, thoroughly understanding lithium battery configuration options is crucial before assembling a battery pack, ensuring you obtain the battery solution that best suits your needs.