Project 1 Mechanical design of battery pack
Aim: Battery pack capacity: 18 kWh Cell: ANR26650M1-B Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.
Introduction
With the increasing demand for energy storage solutions, lithium-ion battery packs play a crucial role in various applications, including electric vehicles (EVs) and renewable energy storage. This project focuses on designing an 18 kWh battery pack using ANR26650M1-B cells, detailing its structure, performance, and safety features.
Battery Pack Specifications
Total Energy Capacity: 18 kWh
Cell Model: ANR26650M1-B (A123 Systems LiFePO₄)
Nominal Cell Voltage: 3.3V
Cell Capacity: 2.5 Ah
Pack Configuration: 29S75P (29 cells in series, 75 in parallel)
Nominal Pack Voltage: 95.7V
Max Pack Voltage: 104.4V
Min Pack Voltage: 81.2V
Total Pack Capacity: 187.5 Ah
ANR26650M1-B Technical data:
Cell Dimensions | 26 x 65 mm |
Cell Weight | 76 g |
Cell Capacity (nominal/minimum) (0.5C Rate) | 2.5/2.4 Ah |
Voltage (nominal) | 3.3 V |
Internal Impedance (1kHz AC typical) | 6mΩ |
| Power | 2600 W/kg |
Recommended Standard Charge Method | 2.5A to 3.6V CCCV, 60 min |
Recommended Fast Charge Method to 80% SOC | 10A to 3.6V CC, 12 min |
Maximum Continuous Discharge | 50 A |
Maximum Pulse Discharge (10 seconds) | 120 A |
Cycle Life at 20A Discharge, 100% DOD | >1,000 cycles |
Operating Temperature | -30°C to 55°C |
| Storage Temperature | -40°C to 60°C |
Cell Arrangement and Configuration
The pack is designed in a 29S75P topology, meaning:
29 cells in series to achieve the required voltage.
75 cells in parallel to increase the overall capacity.
The cells are arranged in a modular format with individual groups being monitored for thermal and electrical safety.
Enclosure Design & Thermal Management
Material: Aluminum alloy (lightweight, high strength, good heat dissipation)
Cooling System: Passive air cooling with heat sinks
Ventilation: Proper air vents to dissipate excess heat
Structural Integrity: Shock-resistant casing to protect against vibrations and impacts
Battery Management System (BMS) and Safety Features
A BMS is integrated to ensure:
Cell Balancing: Equalizing charge among all cells.
Overvoltage/Undervoltage Protection: Prevents overcharging and deep discharge.
Temperature Monitoring: Sensors placed for real-time heat analysis.
Short-Circuit & Overcurrent Protection: Fuses and circuit breakers included.
A Battery Management System (BMS) is an electronic system that monitors and manages rechargeable batteries to ensure their safe and efficient operation. It performs critical functions such as monitoring battery parameters (voltage, temperature, current), protecting against unsafe conditions (overcharging, over-discharging, overheating), balancing charge among cells to maintain uniform performance, and managing thermal conditions to prevent overheating or freezing. These features collectively enhance battery safety, performance, and longevity.
Applications of the Battery Pack
Electric Vehicles (EVs) : In EVs, battery packs serve as the primary energy source, powering the electric motors that drive the vehicle. They are designed to deliver high energy density and efficiency, ensuring sufficient range and performance. Advanced Battery Management Systems (BMS) within these packs monitor parameters like voltage, temperature, and state of charge to maintain safety and optimize battery lifespan.
Renewable Energy Storage (Solar/Wind Backup) : Battery packs store energy generated from renewable sources such as solar and wind. This stored energy can be utilized during periods when generation is low or demand is high, ensuring a consistent power supply. Energy storage systems help in smoothing the variability of renewable energy and can shift energy usage to peak demand times, enhancing grid stability and efficiency.
Uninterruptible Power Supplies (UPS) : In UPS systems, battery packs provide immediate backup power during electrical outages, protecting critical equipment and data from power interruptions. They are essential in settings like data centers, hospitals, and industrial operations where continuous power is crucial. Modern UPS solutions often incorporate advanced battery technologies to offer reliable and efficient power backup.
Industrial Energy Storage Systems : Battery packs in industrial settings support large-scale energy storage needs, aiding in load leveling, peak shaving, and providing backup power. They enhance operational efficiency by managing energy demand and supply, reducing costs, and ensuring reliability. These systems are pivotal in integrating renewable energy sources and maintaining power quality in industrial applications.
Conclusion
The designed 18 kWh battery pack with ANR26650M1-B cells provides a safe, efficient, and scalable energy storage solution. Its robust BMS, thermal management, and enclosure design ensure longevity and reliability for various applications.
Future Scope
Integration of active cooling for enhanced performance.
Implementation of AI-based predictive maintenance for battery health monitoring.
Development of higher energy-density versions using next-generation lithium-ion cells.