Project 1 Mechanical design of battery pack
Pack Capacity = 18KWh
Battery Specification:
Battery Pack Calculation:
Architecture:
Battery pack can be arranged in series-parallel or parallel-series configuration in order to obtain the maximum capacity.
Series : Voltage adds up
parallel : current adds up
Assumption:
Here, the pack is assumed to have 400V in order to proceed with the calculations.
Calculations:
No of cells
cell voltage = 3.3V
Total Pack Voltage = No.of cells in series * voltage of individual cells
No. of cells in series = Total Voltage / individual cell voltage
No. of cells in series = 400 / 3.3 = 122 cells
Result: 122 cells needs to be assembled in series
Total Capacity = Total Voltage * Total Ah
18Kwh = 400V * Total Ah
Total Ah = 18KWh / 400v
Total Ah = 45 Ah
battery pack Ah = No. of cells in parallel * Individual cell Ah
No. of cells in parallel = 45Ah / 2.5Ah
No. of cells in parallel = 18
So, the final configuration of the battery pack is 122S18P.
Battery pack Enclosure design and calculations:
Cell Specifications:
Enclosure calculations:
Total Length = individual cell dia * Total No.of cells
Total Length = 26 * 122
Total length = 3127mm
Total width = individual cell length * Total No.of cells
Total width = 65 * 18 = 1170mm
Total Area = Total Length * Total Width
Total Area Needed = 3127mm * 1170mm = 3.66 m2
Total Volume = Total Area * Total height
Total Volume = 3.66m * 3.127 = 11.4 m3
Mechanical connection:
connections such as connection plates and seperators for each cells need to be provided which in turn requires additional of 20-30 mm space around each cells which can increase the total volume.
Colling circuits can be assmbled in the outer periphery of the casing.
Supporting mechanical members are provided around the casing in order to provide mechanical safety for different loadings of vehicle.
Suggestions:
If the vehicle cannot accomodate this pack directly, the pack can be divided into 2 or 3 packs seperatley and can be placed in accordance with the available space.
Sample Designs:
