Project 1 Mechanical design of battery pack

Objective- To design a battery pack of capacity 18 kWh using ANR26650M1-B cell.

Answer-

The Lithium-ion datasheet used for this project is-

https://www.batteryspace.com/prod-specs/6610.pdf

The reference data of ANR26650m1-B battery from A123 systems is used.

Cell Dimensions-

Cell Calculations-

Battery Pack-

A battery pack is a set of any number of (preferably) identical batteries or individual battery cells. They may be configured in a series, parallel or a mixture of both to deliver the desired voltage, capacity, or power density. The term battery pack is often used in reference to cordless tools, radio controlled hobby toys, and battery electric vehicles.

Components of battery packs include the individual batteries or cells, and the interconnects which provide electrical conductivity between them. Rechargeable battery packs often contain a temperature sensor, which the battery charger uses to detect the end of charging. Interconnects are also found in batteries as they are the part which connects each cell, though batteries are most often only arranged in series strings.

When a pack contains groups of cells in parallel there are differing wiring configurations which take into consideration the electrical balance of the circuit. Battery regulators are sometimes used to keep the voltage of each individual cell below its maximum value during charging so as to allow the weaker batteries to become fully charged, bringing the whole pack back into balance. Active balancing can also be performed by battery balancers devices which can shuttle energy from strong cells to weaker ones in real time for better balance. A well-balanced pack lasts longer and delivers better performance.

For an inline package, cells are selected and stacked with solder in between them. The cells are pressed together and a current pulse generates heat to solder them together and to weld all connections internal to the cell.

Battery Pack calculations-

Materials are required to construct a battery pack are-

• Battery cell
• Nickel tabbing
• PCB/PCM/BMS
• PVC shrink wrap
• Insulating paper
• Insulating foam
• Connectors and wires

There are two types of connectors-

1)Square type

2)Hexagonal type

Steps-

1)Insert the cells inside the connectors with +ve and -ve poles kept alternately in adjacent rows.

2)Spot welding with nickel strips to make series connection between the cells.

3)After making series connections, string are connected parallel, which constitutes a module.

4)More such modules are connected in series or parallel as per the requirement.

5)Battery pack with BMS installed.   

Body enclosure-

Complete enclosure of a battery pack-

Conclusion- The mechanical aspects of designing a battery pack is explained in steps and calculations for series and parallel configurations also discussed in detail.