Project 1 Mechanical design of battery pack

Battery pack capacity: 18 kWh

Cell: ANR26650M1-B

Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.

Aim:-To develope a battery pack of 18KW using ANR26650M1-B cells along with there mechnical design.

Theory:-

General required value depending upon a single cell

• Diameter = Ø25.96 / 26 mm = 0.026 m
• Length = 15 / 65 mm = 0.065 m
• Mass = 76 g=0.076 kg
• Single-cell Voltage = 3.3 V
• Capacity = 2.5 Ah (at 0.5C rating)
• Max Continuous Charge Current (C – rate) = 10 A
• Max Pulse Charge Current (C-rate) = 20 A

Mathematical Battery Calculation:

Single Cell Calculation Volume calculation

= pi*(r^2)h

= pi * 0.013² * 0.065

= 0.03451 m³

Used to find out the total volume of the battery pack.

Single Cell Energy (Wh)

= Cell Capacity (Ah) * Cell Voltage (V)

= 2.5 * 3.3

= 8.25 Wh

Used to calculate the total energy of the battery pack.

Single Cell Energy Density

Volumetric energy (Wh/m³) = Single Cell Energy / Volume of each cell

= 8.25 Wh / 0.03451 m³

= 289.77 Wh/m³

Gravimetric energy (Wh/kg) = Single Cell Energy / Single Cell Mass

= 8.25 Wh / 0.076 kg

= 108.552 Wh/kg

Calculation of High Voltage Battery Pack for an EV :

Our car must conatin 18KWh battery in total ,So to make the desired capacity we need to arrage the cells in series and parallel combition to achive 18kwh as the final capacity of the battery pack.

Assuming the Nominal voltage for series connection = 140V

• Number of cells connected in series

= Nominal voltage of series connection / Nominal voltage of a single cell

= 140V / 3.3 V

= 42

45 Cells will be connected in a series connection to provide a proper voltage.

50 cells will be connected in parallel to provide a proper capacity power.

• Battery pack capacity

= No. of cells connected in parallel * Single cell capacity (Ah)

= 52 * 2.6 Ah

= 130 Ah

The battery pack final capacity:

=Total volatge x Total current

=140*130

=18.2KWh

The value of battery pack capacity is used for the total power required by the vehicle.

• Total number of cells for battery pack

= No. of cells connected in parallel * No. of cells connected in series

= 42 * 52

= 2184

2184 Cells will be used to make a complete battery pack.

• Volume of battery pack

= Total no. of cells for batter pack* Volume of single cell

=2184* 0.03451

=75 m³

• Mass of battery pack

= Total no. of cells for batter pack * Mass of single cell

= 2184 * 0.076 kg

= 165kg

It is the total weight of cells connected in parallel or series.

Structrual Design of the battery Pack:

While developing any battery pack multiple cells are used and by using cells they are connected by using the metaks strips in series or parallel combination depending on the required Volatge and current.

Connecting Plate:

This a nickel strip which is used to connect battery cells with each other to make the complete battery pack.

Generally the Nickel strips are pure to reduce the resistance and reduce the heat and the battery can give a long life,The pure nickel is not a corrisive material so the battery connection will not rust due to any mositure or water conatct which will iimprove the relaibilty of the battery pack.

Holder Case:

This type of holder cases are used to hold the battery cells with each other this will help in making connections and also the proper shape and size of the battery can be maintained.

This holders will give a uniform structure to the battery module.And this will also provide ventilation between the cells which will increase the life of thebattery module.Generaly made from plastic.

Final Battery module with Connection and holder :

BMS:

The BMS is an electronic system that manages a rechargeable battery to ensure it operates safely and efficiently. It is designed to monitor the paramaters associated with the battery packs and their individual cells, applying the collected data to eliminate safety risks and optimise the battery performance.

Thermal Managment:

To get the desired performance of the battery the battery must operate at the optimum temperature.TO do so the battery requires both cooling as well as heating.

Structural BUild For the Battery Pack:

The Steel Structure is used to protect the battery module.This Battery pack contain multiplr battery Cells and battery modules and BMS.

This will give the battery pack a good structural streangth and according to the space available this battery pack size can be modified .

In case of any accident this structure will not allow the cells to fall.

Conclusion:

Thus a battery pack has been designed using ANR26650M1-B cylindrical cells by calculating several cells, battery voltage and capacity. The required size of the battery pack have also been calculated.