Project 1 Mechanical design of battery pack

The above cell has the specifications of nominal voltage (V)=3.3V

Cell capacity (Ah) =2.5Ah

Cell energy (E)=3.3*2.5=8.25kwh.

We need to build 18kwh capacity battery pack.

let us assume the vehicle motor has the voltage rating of 120V.

Then the battery pack should have the same voltage rating to satisfy the load .ie, 120V.

The battery pack current rating (capacity )is given by Energy / voltage

capacity (ah) = 18000/120 = 150Ah capacity.

Let us assume from the modules level;

One module has 5S3P ie, 5 series and 3 parallel cells

5series cells voltage = 3.3*5= 16.5V

3parallel cells capcity=2.5*3=7.5Ah

so, 5S3P module can provide 16.5V and 7.5Ah.

5S3P provides 123.75 wh capacity.

So The no of 5S3P modules reiquire to provide 18000wh is given by

18000/123.75=145.45 similar to 146 modules.

Cells for 1 module is 5*3= 15 cells.

Total no cells required to form the battery pack are 15*146=2190 cells.

WE can get 18067.5wh from the 123.75 kwh *146 modules

The remaing we will consider as losses.

Another thing is we can't get exact 18kwh if we arrange them theritically calculations due to their internal connection resistance and losses also.

STEPS INVOLVED IN MECHANICAL DESIGN:

1] Cell seclection.

2]Cell Holders

3]Electrical connections

4]Module making.

5]BMS

6]Enclosing of battery pack