Project 1 Mechanical design of battery pack

Prepare a detailed battery pack drawing of [Battery pack capacity: 18 kWh, Cell: ANR26650M1-
B] along with its enclosure. State your assumptions.

Details of Cell: ANR26650M1-B:

ANR26650M1-B specification:
Nominal Rating:
 voltage :3.3 volts
 capacity:2.5Ah
 energy: 8.25Wh
 specific power: 2600W/kg
 impedence(1KHz AC typical) 6 mΩ
 cell type: 26650 lithium ion power cylindrical cell.
Discharging:
 max.continuous discharage: 50A
 max pulse discharge current > 50% SOC (10sec): 120A
 minumum voltage:2 volts
 temperature: -30 to 55 degree celcious
charging:

 recommended std.charge: 2.5A
 max charge rate:10A
 max pulse charge current<50% SOC (10sec) :25A
 float voltage: 3.45 volts
mechanical parameters:
 diameter: 25.96 +/- 0.5 mm
 length: 65.15+/- 0.5 mm
 mass : 76g

calculation as per assumptions: 18 KWh battery pack.
 calculation for designing an 18 KWh battery pack basically 18 KWh is energy require to achive the
vehicle it proper range.and its depend on the voltage(V) and amp-hr capacity(Ah)

1] single cell energy(Wh) [the value of a single cell energy is used to calculate the total energy of the
battery pack]:
single cell energy(Wh)= cell capacity(Ah)* cell voltage(V)
= 2.5Ah *3.3V
= 8.25 Wh
2] single cell volume calculation:
single cell volume = pi(r^2)*h
= 3.14(0.013^2)*0.065
= 0.03451 m^3
3] single cell energy density:
A] volumetric energy(Wh/m^3) = single cell energy / volume of each cell
= 8.25Wh / 0.03451 m^3
= 239.0611 Wh/m^3

B] gravimetric energy(Wh/kg) = single cell energy / single cell mass
= 8.25Wh / 0.076 kg
=108.5526 Wh/Kg

calculation of high voltage battery pack

for design and calculation of battery pack here,i assume a vehicle to achive 200km in 18 KWh battery pack
also i assume 145.2 nominal voltage for series connection.
sowe assume that,
vehicle range = 200 Km
battery pack capacity = 18.1210KWh
now,
4] we will calculate per Km average energy requirement = 18120.96 (Wh)/200 (Km)
= 90.60 Wh/Km
therefor,
battery pack total energy = average energy * km
= 90.60Wh * 200km
= 18120.96 Wh
lets assume nominal voltage for seres connection= 145.2 V basically this depends upon the motor
power,we can decide the value according to the motor.
5] number of cell connected in series = nominal voltage of seres connection/nominal voltage of a single
cell
= 145.2V/ 3.3V
= 44 cell
44 cell will be connected in a series connection to provide a proper voltage.

6] energy for battery pack(Wh) = number of cell connected in series * single cell energy
= 44* 8.25Wh
= 363 Wh
7]number of cell connected in parallel = battery pack total energy(Wh)/energy for battery pack(Wh)
= 18120.96 Wh/363 Wh
= 50 cell
50 cell will be connected in a parallel to provide a proper capacity power.

8] battery pack total energy(Wh) = no. of cell connected in parallel * energy for battery pack
= 50* 363 Wh

= 18.150 KWh
9] battery pack capacity(Ah) = no. of cell connected in parallel * single cell capacity(Ah)
= 50*2.5 Ah
= 125 Ah
the value of battery pack capacity is used for the total power required by the vehicle.
10] total number of cell for battery pack = no. of cell connected in parallel * number of cell connected in
series
= 50*44
=2200 cells
2200 cells will be used to make a complete battery pack.
11] mass of battery pack = total number of cell for battery pack * mass of single cell
= 2200 * 0.076 kg
= 167.2 kg
167.2 kg its the total weight of cell connected in parallel and series
12] total volume of the battery pack = total number of cell for battery pack * volume of single cell
= 2200 * 0.0345 m^3
= 75.9 m^3
75.9 m^3 its the volume occupied by total cell used in battey pack.

13] cell peak current(A) = C rate(max pulse charge current)* single cell capacity
= 20* 2.5
= 50A
14] battery pack peak current(A) = cell peak current(A) * no. of cell connected in parallel
=50*50
= 2500A
15] battery pack peak power(W) = battery pack peak current(A) * voltage of series connection
= 2500 A * 145.2
= 363 KW
16] cell continuous current(A) = C rate(max continuous charge current)* single cell capacity

= 10* 2.5
= 25A
17] battery pack continuous current(A) = cell continuous current(A) * no. of cell connected in parallel
= 25*50
= 1250 A
18] battery pack continuous power(W) = battery pack continuous current(A) * voltage of series
connection
= 1250 A * 145.2
= 181.5 KW

Details of Cell: ANR26650M1-B:

Battery holder:

Electric connection:

Battery pack with BMS[battery management system]: