Project 1 Mechanical design of battery pack

                                                      Note-This is Live EV Batch 21.
Ans-

 Objective-Make a battery pack of 18kWh with cell specification of ANR26650M1-B.

Li-ion cell(ANR26650M1-B)-

There are many companies who makes Li-ion battries.Here taking the reference of LITHIUMWERKS.

Dimensions-

Cell Specification-

Various Characteristics from reference data sheet-

Assumptions-

We are assuming the required total voltage to run the EV and other acessories is 400V.

So we have to make battery pack of 18kWh for a 400V input voltage.

Battery Calculation-

Voltage=3.3V

Capacity=2.5Ah

• So total enegy stored in a cell =v*i(Ah)

                                            =3.3*2.5

                                            =8.25Wh

• As we have to give output energy as 18kWh.

        So No. of requird cell=Total energy of battery pack/total energy of a cell

                                      =(18*1000)/8.25

                                      =2182

• As we have assumed the output voltage =400V

       As we know that total output voltage from a battery pack is a combination of voltage from series and parallel                         connections.

      In series connection-Voltage gets added and current remains same.

      In parallel connection-Current gets added and voltage remains same.

      So series connection is responsible for voltage-

            No. of series connection=Total output voltage /individual cell voltage

                                              =400/3.3

                                              =122

      Total 122 cell be arranged in series.

      Total power from 122 cell in series=Total no. of cell connection in series*individual cell energy

                                                       =122*8.25

                                                       =1006.5Wh

      The above calculated power will not run the motor as required capacity is 18kWh.So we need more such connection                which will be added in parallel otherwise overall voltage label will increase.

      so no. of parallel connection=Totala capacity/one series combined capacity

                                               =18*1000/1006.5

                                               =18

       so no. of parallel connection is 18.

• So we have to make a arrangment of 122  in series and 18 parallel.that is 122S18p

        Total no. of cell=122*18

                              =2196

Total number of requird cell=2196.

Thus the battery model is said to be 122S18P configuration Which uses 2196 cell.

Total capacity =2196*8.25

                     =18117  which is slightly higher than required.

The overall capacity (Ah) of a battery pack is as=2.5*18

                                                                     =45Ah

Enclouser construction -

 Side clearence-

•    Cell in series-

• Cell in parallel-

• Cell holder-

Length of casing=No. of cell in a row*(cell dia. + margin of both side of cells)+clerence at side(2*(cell dia. +margin))

                       =122*(26+4)+60

                       =3720mm

Breath of casing=No. of cell in parallel*(cell dia. + margin of both side of cells)+clerence at side(2*(cell dia. +margin))

                       =18*(26+4)+60

                       =600mm

Height of casing=Height of cell + connecting strip thickness(assume 35mm)

                       =65+35

                       =100mm

So Volume required for battery pack=L*B*H

                                                    =3720*600*100

                                                    =223200000mm^3

                                            or   0.2232m^3

So total volume requird for battery pack=0.2232m^3.

Battery Pack Weight-

    Total weight of battery pack=Cell weight*total no. of cell + weight of accessories(assume 4.5kg)

                                            =0.076*2196+4.5

                                            =171.396kg

Joining tecnology of cell-

There are some methods of joining the cell listed below-

1. Ultrasonic metal welding
2. Resistance welding
3. Laser beam welding
4. Wire bounding
5. Mechanical joining

Building step of Battery Pack