Project 1 Mechanical design of battery pack
SOLUTION
ANR26650M1-B Specifications
Nominal Ratings Voltage: 3.3 Volts
Capacity: 2.5 Ah Energy: 8.25 Wh
Specific Power: 2600 W/kg
Impedance (1KHz AC Typical) 6 mU
Cycle Life at 1C/1C, 100%
DOD: > 4000 cycles
Cell Type: 26650 Lithium Ion Power Cylindrical Cell
Discharging
Max Continuous Discharage: 50 AH
Max Pulse Discharge Current >50% SOC (10s): 120 A
Minimum Voltage: 2 Volts
Temperature: -30°C to 55°C
Charging
Recommended Standard Charge: 2.5 Amps
Max Charge Rate: 10 Amps
Max Pulse Charge Current <50% SOC (10s): 25 A
Float Voltage: 3.45 Volts
Recommended charge V & Cut-off Current: 3.6 Volts, taper to 125mA
Temperature (reduce charging current to 250m4 when under 0°C): 0°C to 55°C
Mechanical Diameter: 025.96 +/- 0.5 mm (1.0-)
Length: 65.15 +/- 0.5 mm (2.6") Mass: 76 g
Calculation as per assumptions:- 18kWh
Battery Pack calculation for designing an 18kWh battery pack, basically 18kWh is energy require to achieve the vehicle its proper range. It is depending upon the voltage (V) parameter and ampere-hour or capacity (Ah). Here we design a high voltage battery pack for an electric vehicle to achieve its range up to 220 km. For this calculation, I assumed 145.2 V a nominal voltage for series connection.
Basically, the value of the volume of the cell is used to find out the total volume of the battery pack. - Single Cell Energy (Wh) = Cell Capacity (Ah) x Cell Voltage (V) = 2.6 x 3.3 = 8.58 Wh The value of a single cell is used to calculate the total energy of the battery pack. -Single Cell Energy Density
Basically, the value of the volume of the cell is used to find out the total volume of the battery pack. - Single Cell Energy (Wh) = Cell Capacity (Ah) x Cell Voltage (V)
= 2.6 x 3.3
= 8.58 Wh
The value of a single cell is used to calculate the total energy of the battery pack. -Single Cell Energy Density Volumetric energy (Wh/mA3) = Single Cell Energy / Volume of each cell = 8.58 Wh / 0.03451 mA3 = 248.62 Wh/mA3 Gravimetric energy (Wh/kg) = Single Cell Energy / Single Cell Mass = 8.58 Wh / 0.076 kg = U2.89 Wh/kg Calculation of High Voltage Battery Pack For design and calculation of battery pack here, I assume a vehicle to achieve 250 km in 18 kWh battery pack. Also, I assume 145.2 nominal voltage for series connection.
So, Vehicle Range = 250 KM (assumed) Battery Pack capacity = 18.121 kWh or 18120.96 Wh (For better and accurate calculation here I change kWh)
Now, We will calculate per km average energy = 18120.96 / 250
Therefor, Battery Pack total energy = Average energy x km = 72.483 x 250 = 18120.96 Wh or 18.120 kwh
Let's assume Nominal voltage for series connection = 145.2 V, Basically, this depends upon the motor power, We can decide the value according to the motor. - Number of cells connected in series = Nominal voltage of series connection / Nominal voltage of a single cell =145.2 V / 3.3 V = 44
44 Cells will be connected in a series connection to provide a proper voltage.
- Energy for battery pack (wh) = No. of cells connected in series x Single-cell energy
= 44 x 8.58 wh = 377.52 wh
-- Number of cells connected in parallel
= Battery pack total energy (wh) / Energy for battery pack (wh) =18120.96/377.52 = 48 48 cells will be connected in parallel to provide a proper capacity power.
-- Battery pack total energy (wh) = No. of cells connected in parallel x Energy for battery pack (wh) = 48 x 377.52 = 18120.96 wh or 18.120 kWh
-- Battery pack capacity = No. of cells connected in parallel x Single cell capacity (Ah) = 48 x 2.6 Ah = 124.8 AhThe value of battery pack capacity is used for the total power required by the vehicle. -- Total number of cells for battery pack = No. of cells connected in parallel x No. of cells connected in series
=48x44
-- Battery pack capacity = No. of cells connected in parallel x Single cell capacity (Ah) = 48 x 2.6 Ah = 124.8 AhThe value of battery pack capacity is used for the total power required by the vehicle. -- Total number of cells for battery pack = No. of cells connected in parallel x No. of cells connected in series =48x44 = 2112
2112 Cells will be used to make a complete battery pack. -- Mass of battery pack = Total no. of cells for batter pack x Mass of single cell = 2112 x 0.076 kg = 160.512 kg it is the total weight of cells connected in parallel and series.
-- Total volume of the battery pack = Total no. of cells for batter pack x Volume of single cell = 2112 x 0.0345 = 72.89 mA3
This is the volume of2112 cells which are used in the battery pack system.
Cell peak current (A) = C rate (Max Pulse Charge Current) x Single cell capacity = 20 x 2.6
Battery pack continuous power (w) = Battery pack continuous current x Voltage of series connection =1248 x145.2 = 18120.96 or 18.120 Kwh