Project 1 Mechanical design of battery pack
Battery pack capacity: 18 kWh
Cell: ANR26650M1-B
Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.
Ans:-
The features of the Cell:ANR26650M1-B are mentioned below :
ANR 26650 M1-B Specifications :
Nominal Ratings
Voltage: 3.3V
Capacity: 2.5Ah
Energy: 3.3*2.5=8.25Wh
Specific Power: 2600W/kg
Impedance (1KHz AC Typical): 6mΩΩ
Cycle Life at 20A Discharge, 100% DOD: >1000 cycles
Cell Type: 26650 Lithium ion Power Cylindrical Cell
Discharging
Maximum Continuous Discharge: 50A
Maximum Pulse Discharge (10 seconds): 120A
Minimum Voltage: 2V
Operating Temperature: -30°C to 55°C
Charging
Recommended Standard Charge Method: 2.5A to 3.6V CCCV, 60 min
Recommended Fast Charge Method to 80% SOC: 10A to 3.6V CC, 12 min
Mechanical
Diameter: 25.96 +/-0.5 mm
Height(max): 65.15 +/-0.5 mm
Mass: 76g
Calculation as per assumptions:- 18kWh battery pack
Calculation for designing an 18kWh battery pack,basically 18kWh is the energy required to achieve the vehicle its proper range.It is depending upon the voltage parameter(V) and ampere-hour or capacity (Ah).
Here we design a high voltage battery pack for an electric vehicle to achieve its range upto 320Km.For this calculation, we assume 171.6V a nominal voltage for series connection.
Basically, the volume of the cell is used to find out the total volume of the battery pack.
Single cell energy (Wh)
=Cell Capacity (Ah)*Cell Voltage (V)
=2.6*3.3
=8.58Wh
The value of a single cell is used to calculate the energy of the battery pack
Single cell energy density
Volumetric Energy (Wh/m^3)=Single cell energy/Volume of each cell
= 8.58 Wh/0.03451m^3
= 248.62 Wh/m^3
Gravimetric Energy (Wh/kg)=Single cell Energy/Single cell mass
= 8.58 Wh/0.076kg
=112.89 Wh/kg
Calculation of High Voltage Battery pack :
For design and calculation of battery pack here, we assume a vehicle to achieve 350 Km in 18 KWh battery pack.Also, we assume 171.6 V nominal voltage for series connection.
So,
Vehicle range = 350 KM (assumed)
Battery Pack Capacity= 18.121 KWh or 18121 Wh (For better and accurate calculation here we change KWh)
Now, per Km average energy=18121/350
=51.774 Wh/Km
Let's assume nominal voltage for series connection = 171.6V.Basically, this depends on 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)
= 171.6/3.3
=52
52 cells will be connected in series connection to provide a proper voltage.
-Energy for battery pack (Wh)
=No. of cells connected in series * Energy for battery pack (Wh)
=52*8.58 Wh
=446.16 Wh
--No. of cells connected in parallel
=Battery pack total energy (Wh)/Energy for battery pack (Wh)
=18121/446.16
=41
41 cells will be connected in parallel to provide for capacity power.
--Battery pack total energy (Wh)
=No. of cells connected in parallel*Energy for battery pack (Wh)
=41*446.16
=18292.56 Wh or 18.292kWh
--Battery Pack Capacity
=No. of cells connected in parallel*Single cell Capacity(Ah)
=41*2.5 Ah
=102.5 Ah
The value of Battery capacity is used for the Total Power required by the vehicle.
--Total number of cells for battery pack
=Number of cells connected in parallel*Number of cells connected in series
=41*52
=2132
2132 cells will be used to make a complete battery pack.
--Mass of battery pack
=Total number of cells for battery pack*Mass of single cell
=2132*0.076kg
=162.032kg
It is the total weight of the vehicles connected in series and parallel.
--Total volume of the battery pack
=Total number of cells for battery pack*Volume of single cell.
=2132*0.0345m^3
=73.554 m^3
This is the volume of 2132 battery packs connected in the battery pack system.
--Cell Peak Current (A)
=C rate (Max pulse charge current)*Single cell Capacity
= 20*2.5
= 50 A
--Battery pack peak Current (A)
=Cell Peak Current*No. of cells connected in parallel
=50*41
= 2050 A
It is used for the operation of Battery pack.By this way, a vehicle will decide how much power os requirede to move.
--Battery pack Peak Power (W)
= Battery pack peak Current*Voltage of Series Connection
=2050 A*171.6 V
= 351780 W or 351.78 kW
--Cell continous current (A)
=C rate(Maximum Continous charge current)* Single Cell capacity
=10*2.5
=25 A
--Battery Pack Continous Current (A)
= Cell continous current*No. of cells connected in parallel
= 25*41
= 1025 A
This is the Current which is supplied continously to the whole Battery pack system.
--Battery Pack Continous Power(W)
= Battery Pack Continous Current * Voltage of Series connection
= 1025 A*171.6 V
= 175890 Wh or 175.89 kWH
Detailed Battery Pack drawing along with its Enclosure :
BATTERY SPACER AND HOLDER FOR CYLINDRICAL NETWORK :
NICKEL STRIPS :
Nickel strip is generally used in battery building. Its due to its efficiency of usage in spot welding and soldering as well its high corrosion resistance over time. It has good properties and excellent resistance to many corrosive environments. The pure nickel will never get rust after it applied to battery packs. It won’t affect the current transfer between batteries.
Pure nickel strips are the material you want, but many vendors swap out it for nickel-plated steel strips, which are poorer and have greater resistance – not suitable for most battery projects.
we give 100% pure nickel strip. We verify all of our strips to assure that you are getting the high-quality pure nickel. It also solder incredibly quickly, so you can weld them onto your existing busbar connections to raise the supply of current you can pull through the busbars. The benefits are nearly limitless!
BATTERY ENCLOSURE :
Design Benefits :
• Up to 50 percent lighter than an equivalent steel design
• Best-in-class mass energy density at more than 160 watt-hours per kilogram, an extremely efficient design for OEMs and Tier 1 battery pack manufacturers.
• Accommodates all battery cell types and is designed particularly for battery electric vehicles with larger power packs such as pick-up trucks, sport utility vehicles and crossovers.
• Most cost-effective aluminum solution for mass production electric vehicles when compared to aluminum extrusion and casting-intense designs.
• Low price premium on $/kg saved compared to equivalent steel designs at substantially
lower weight.
Performance Benefits
• Provides automakers the ability to achieve deep
drawn, complex shapes tailored to specific vehicle
design requirements
• Extends range, allowing vehicles to go 6-10 percent
further on a single charge
• Protects batteries from road debris and vehicle crashes
AS we know, Power*(p)=Current(i)*Voltage(v) kW
3.3*2.5=8.25 kW
To get 18 kWh we are assuming 48s48p pack
i.e, 48*48=2304 cells.
Series connection gives 48*3.3=158.4V
Parallel connection gives 48*2.5=120A
From this we can get
158.4*120=19.008 kWh energy or capacity.
We design battery pack for 48s and 48p cells along with battery spacers to hold cells and for their connection nickel strip is used.
When cells are connected by nickel strips spot welding is used so that cell not damage.
FINAL APPEARANCE :
