What Is a 21700 Battery Pack
Xiaowei New Energy A 21700 battery pack is a high-capacity, cylindrical lithium-ion battery pack designed for applications requiring high energy density and performance, such as electric vehicles and energy storage systems.
Introduction to 21700 Battery Packs by Xiaowei New Energy
Xiaowei New Energy specializes in the production of advanced 21700 battery packs, which are cylindrical lithium-ion batteries known for their high energy density and performance. These battery packs are widely used in electric vehicles and energy storage projects, offering significant advantages over traditional battery technologies.
Definition and Characteristics of a 21700 Battery Pack
A 21700 battery pack consists of multiple 21700 cells, each with a diameter of 21 mm and a height of 70 mm, arranged in series or parallel configurations to meet specific power and capacity requirements.
The 21700 cell is a type of cylindrical lithium-ion battery, similar to the 18650 but with a larger size, allowing for higher capacity and energy density. The 21700 battery pack is designed to provide reliable and efficient power solutions for various applications, including electric vehicles (EVs) and energy storage systems (ESS).
Key characteristics of 21700 battery packs include:
- High energy density: Up to 700 Wh/L
- Long cycle life: Over 1000 cycles
- High discharge rate: Suitable for high-power applications
- Compact design: Efficient use of space in EVs and ESS
| Item | Details |
|---|---|
| Definition | 21700 battery pack is an assembled power unit made of 21700 cylindrical lithium-ion cells. 21700 refers to cell dimension: 21mm diameter, 70mm height, widely adopted for mid-to-high power portable and stationary energy systems. |
| Cell Core Specs | Nominal voltage: 3.7V; Charge cut-off: 4.2V; Discharge cut-off: 2.75V; Single cell typical capacity: 4000mAh – 5000mAh |
| Pack Configuration | Available in single, parallel, series-parallel combinations. Equipped with BMS/PCM to manage cell balance, overcharge, overdischarge, overcurrent and short-circuit protection. |
| Key Advantages | Higher energy density vs 18650; larger capacity than 20700; stable discharge capability; mature manufacturing; reduced number of cells for same total energy |
| **Limitations | Larger physical size; higher weight than 18650; strict cell consistency requirement for series packs; proper thermal management required under high continuous discharge |
| Application Scenarios | E-bicycles, power tools, portable power stations, AGVs, energy storage systems, robot power supplies, light electric vehicles |
| Safety & Maintenance | Must use matching BMS; prevent piercing, impact and high-temperature working environment; regular check for cell voltage balance; use dedicated lithium battery chargers |
Energy Density and Performance of 21700 Battery Packs
The 21700 battery pack offers significantly higher energy density compared to other cylindrical lithium-ion battery packs, making it an ideal choice for applications that require both high capacity and compact size.
Energy density is a critical factor in determining the overall performance of a battery pack. The 21700 battery pack can achieve up to 700 Wh/L, which is a substantial improvement over the 18650 cells, typically offering around 250-300 Wh/L. This higher energy density translates to longer run times and more efficient use of space in applications such as electric vehicles and energy storage systems.
Performance characteristics of 21700 battery packs include:
- High discharge rates: Capable of delivering high power output
- Low self-discharge: Maintains charge over extended periods
- Wide operating temperature range: Suitable for various environmental conditions
Applications of 21700 Battery Packs in Electric Vehicles
21700 battery packs are widely used in electric vehicles due to their high energy density, long cycle life, and ability to deliver high power output, making them an ideal choice for EV manufacturers.
Electric vehicles (EVs) require high-capacity, high-performance battery packs to ensure long driving ranges and efficient power delivery. The 21700 battery pack meets these requirements by providing a balance of high energy density and high discharge rates. This makes it an excellent choice for EVs, where space and weight are critical factors.
Key benefits of 21700 battery packs in EVs include:
- Extended driving range: Higher energy density means more miles per charge
- Fast charging: High discharge rates enable rapid recharging
- Reliability: Long cycle life ensures consistent performance over time
Applications of 21700 Battery Packs in Energy Storage Systems
21700 battery packs are also extensively used in energy storage systems (ESS) due to their high energy density and long cycle life, making them suitable for both residential and commercial energy storage applications.
Energy storage systems (ESS) are essential for storing and managing electrical energy, particularly from renewable sources like solar and wind. The 21700 battery pack’s high energy density and long cycle life make it an ideal choice for ESS, providing efficient and reliable energy storage solutions.
Key benefits of 21700 battery packs in ESS include:
- High energy density: Stores more energy in a smaller footprint
- Long cycle life: Ensures the system remains operational for many years
- Scalability: Can be configured to meet various energy storage needs
21700 Battery Packs FAQS
| No. | Question & Answer |
|---|---|
| Q1 | Q: What is a 21700 battery pack?
A: A 21700 battery pack is an assembled power unit made from 21700 cylindrical lithium-ion cells. Cells are connected in series and parallel, integrated with BMS, nickel busbars, cell holders, insulation materials and outer casing to achieve target voltage, capacity and discharge performance. |
| Q2 | Q: What does 21700 mean?
A: 21700 refers to cell dimensions: 21 mm diameter and 70 mm length. It is a larger cylindrical format compared to 18650, designed for higher single-cell capacity and energy. |
| Q3 | Q: What is the nominal voltage of a single 21700 cell?
A: NMC 21700 cells have a nominal voltage of 3.7V, fully charged at 4.2V. LFP 21700 cells feature 3.2V nominal voltage and full charge voltage of 3.65V. |
| Q4 | Q: What are typical capacity ranges for 21700 cells?
A: Common capacities are 4000mAh to 5000mAh. Premium high-energy versions can reach above 5000mAh, while power-focused 21700 cells trade capacity for higher discharge rates. |
| Q5 | Q: What is the main difference between 21700 and 18650 cells?
A: 21700 has bigger volume and higher single-cell capacity. Fewer cells are needed to reach the same total energy, cutting welding points and assembly workload. 18650 has wider supply availability and lower unit cost. |
| Q6 | Q: What are energy-type and power-type 21700 cells?
A: Energy-type 21700 cells maximize capacity for long runtime with moderate continuous current. Power-type variants support high-rate discharge for heavy loads with slightly lower capacity. |
| Q7 | Q: What components make up a complete 21700 battery pack?
A: 21700 cells, plastic cell holders, nickel strips / busbars, BMS protection board, sampling wires, insulation paper, thermal pads, sealant and plastic or metal housing. |
| Q8 | Q: Why is BMS required for 21700 battery packs?
A: BMS monitors cell voltage, current and temperature. It protects the pack against overcharge, overdischarge, overcurrent and short circuit, and performs cell balancing to extend service life and improve safety. |
| Q9 | Q: What welding methods are used for 21700 pack assembly?
A: Resistance spot welding is standard for nickel strip interconnection. Ultrasonic metal welding is used for high-current packs with thicker conductive busbars. |
| Q10 | Q: What are common series-parallel configurations for 21700 packs?
A: 1S (3.7V) for portable electronics; 10S (36V), 13S (48V) for e-bikes and light EVs. Parallel groups increase total capacity and continuous discharge current. |
| Q11 | Q: What are typical applications of 21700 battery packs?
A: E-bikes, electric scooters, portable power stations, power tools, drones, garden equipment and light mobility devices. |
| Q12 | Q: What are the advantages of 21700 battery packs?
A: Higher per-cell energy, fewer cells in pack design, reduced welding joints, lower assembly labor, better pack energy density and compact system layout. |
| Q13 | Q: What are the disadvantages of 21700 battery packs?
A: Higher cell cost than 18650, smaller global supply base. Larger cell size limits use in ultra-small compact devices. Single cell failure releases more thermal energy. |
| Q14 | Q: What safety hazards should be considered for 21700 packs?
A: Overcharging, short circuit, mechanical puncture and thermal runaway. Since each 21700 cell stores more energy than 18650, cell failure can trigger more severe heat release. |
| Q15 | Q: What certifications are needed for exported 21700 battery packs?
A: UN38.3 transport test, IEC62619, CE. For EU market sales, battery passport and ESG material traceability records are mandatory. |
| Q16 | Q: What is the typical cycle life of a 21700 NMC battery pack?
A: Generally 500–900 full cycles to 80% capacity retention. LFP 21700 packs can achieve 2000+ cycles under proper temperature and load conditions. |
| Q17 | Q: What quality tests are performed on finished 21700 packs?
A: OCV and internal resistance test, capacity calibration, insulation resistance test, hipot test, charge-discharge aging test, short-circuit protection test and weld visual inspection. |
| Q18 | Q: Is cell sorting necessary before assembling 21700 packs?
A: Yes. Cells must be grouped with matched OCV, internal resistance and capacity. Mismatched cells cause voltage imbalance, accelerated degradation and reduced pack safety. |
| Q19 | Q: Can 21700 battery packs be produced on semi-auto or fully automatic assembly lines?
A: Yes. Semi-automatic lines fit small and medium custom batches. Fully automatic production lines are deployed for mass manufacturing of standardized 21700 packs. |
| Q20 | Q: What warning signs mean a 21700 battery pack must stop using?
A: Cell swelling, abnormal heating during charge or discharge, sudden voltage drop, strange odour or smoke. Stop usage immediately and isolate the battery safely. |
Conclusion
A 21700 battery pack is a high-capacity, cylindrical lithium-ion battery pack that offers superior energy density and performance, making it a preferred choice for electric vehicles and energy storage systems.
Xiaowei New Energy’s 21700 Battery packs are designed to meet the demanding requirements of modern applications, providing reliable and efficient power solutions. Whether for electric vehicles or energy storage systems, the 21700 battery pack is a versatile and high-performing option that delivers on both capacity and performance.
