Project 1 Mechanical design of battery pack

let's look at the datasheet of ANR26250M1-B

Fig1:-Physical dimension of battery 

Fig2:-Parameter of battery 

Fig3:-Charge and discharge curve of the battery.

The fig4:-Charging curve of li-ion battery 

so right now we had took the cell as anr 26650m1-b

so from their nomenclature, it's having a diameter of 26 mm and a height of 65 mm

and we need to make the cell pack from these cells.

so the voltage which we can extract from the data-sheet is V=3.3v

And the nominal current is 2.56Ah 

In the question, it's clearly given that we wanted a battery pack of 18,000 Wh

Battery Pack Design 

Now let's design the battery pack 

Number of cells in series (ns)=energy we required/(nominal Voltage* capacity)

N=18000/(3.3*2.5)

N=2181.23 cells 

N is approximate 2182 cells

Now a number of cells in series Ns=pack voltage/nominal voltage of cell

Ns=720/3.3

Ns=219

Number of cells in parallel=Number of cells/number of cells in parallel

Np=2181/219

Np=10

we wanted 

219Ns 10 NP

now we are getting 

Ns=3.3*219

Ns=722

Np=2.56*10

Np=25.6

C rate 

so this will be charged at 15 A and Discharge is possible at 50A for 2 seconds

so that both of the conditions will be staying  and we have over-designed the pack and it is an good practice to over-design by 5%

This will tell us how many the cells are in series and parallel.

So for a Battery pack, we need to consider some other consideration that is explained below 

Length of battery pack (L)=Ns*and the dia of each cells+(space*(n-1 of series cell)+(end space*2)

L=26*219+6*218+10*2

L=7022 mm

L=7.02m

Wdith of Battery Pack(W)=Dia od each cell*Np+(Space *(n-1of Np))+End space*2

W=26*10+6*9+10*2

W=334mm

W=0.334 m

Height of battery Pack=cell height+Nickle sheet height+cusion height

H=65+2*2+10*2

H=89 mm

H=0.089

Fig5:-Battery pack overall length and width

Fig6:In detail view of battery pack 

Fig 7:-Battery pack Height 

here is the cell holder by which we can able to have the cell holder in design 

Fig8:-Cell holder image 

but to hold the cells we need to make the spot welding so that it is shown in the below figure 

 

Fig 9:-Spot welding machine 

and it is  possible to make a single battery pack with having dimensions of 7m*0.33m*0.089m

so we need to spill or with help of a holder, we can obtain the entire battery pack.

Fig10:-Electrode used for spot welding machine

Fig11:-Different spot welding pattern 

Fig12:-Different types of nickel strips used in welding 

Fig13:-Different spot welding patterns on cells 

Fig 14:-Various cells configuration of storage application

Cooling of the battery pack

Fig 15:-Various technology for cooling the battery pack.

here we are going to cool the pack with Air cooling it won't require much space and it is one of the  in this case, we have space constrain.

We have designed a battery for the tractor which is used for aircraft movement