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
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The various design elements to be considered while developing a battery pack are as follows
1. Electrical Design.
* Determination of capacity voltage and current
* High Voltage isolation
* Short Ckt prevention
* Efficient power delivery
2. Thermal Design
* Improve pack efficiency
* Mitigate thermal accidents
* Increase pack life
3. Mechanical Design
* Safe Structure for extreme conditions
* Cost productivity and reliability
* Ease of assembly and service
* Aeshetics compactness and light weight
4. Battery Management System (BMS) Design
* Maintain Cell/pack operating limits
* Prevent events compromising safety
* Control thermal systems
* Communication and logistics
Nanophosphate High power Lithium ion Cell
A123's high performance Nanophosphate lithium ion phosphate battery techmology delivers high power and energy density combined with excellent safety performance and extensive life cycling in a lighter weight more compact package our cells have low capacity loss and impedance growth over time as well as high usable energy over a wide state of a charge range allowing our systems to meet end of life power and energy requirements with minimal pack oversizing.
About Cell:
The Lithium works ANR26650M1-B is the next generation of A123 systems pioneering 26650 cyclindrical cell now with greater power and enegry density and lower impedance This versatile lithium ion cell is suitable for a wide variety of applications and system designs.
About Module:
A battery management system (BMS) is any electronic system that manages a recharagble battery such as by protecting the battery from operating outside its safe operating area, monitoring its state calculating secondary data, reporting that data controlling its environment
EV Design Battery Calculation:
Assumptions:
Battery energy= 18Kwh
Voltage (to run the vehicle)= 400V
* Energy= 18Kwh
* Number of cells (N)= energy / nominal voltage * capacity
N= 18000/ (3.3* 2.5)
N= 2182
We need a minimum of 2182 cells to get 18Kwh energy now based on that we need to decide configuration series and parallel
In series configuration capacity remains the same and voltage will be the sum of individual cell voltage
In a Parallel configuration the volatage remains the same and capacity accumulates
And we assume 400 Volts are need to run the vehicle
The nominal Voltage of one cell is 3.3V
Number of series cell required to produce 400V (Ns)= Voltage required/ nominal voltage of one cell
Ns= 400/3.3
Ns=121.21 = 122
122 Cells are connected in series will generate 400 voltage and capacity of the whole module will be 2.5Ah
Now we need to find the number of cells which will be connected in a parallel configuration
Np = total cell/Ns
Np= 2182/122
Np= 17.8 = 18\
Hence we take 18 cells for each parallel row, although it is exceeding the required capacity that is negligble
Cell Architecture = 122 Series and 18 Parallel = 122S18P
Battery Capacity:
We know parallel configured cell multiples individual cell capacity so
Capacity= Parallel cell row* Individual Cell capacity
Capacity= 18*25
Capacity = 45Ah
Current Supplied by the battery:
We have already calculated battery capacity which is 45Ah means it is going to supply 45A current per hour which can be considered as C- rate
Range
Let's powertrain energy consumpiton 100 Wh/Km at 70% powertrain efficiency
Range = Capacity/ energy consumed per kilometre
Range= 18000/100
Range = 180 Km
So our vehicle will be able to cover around 180 Km with current parameters
ANR26650 cell has 26mm diameter and 65mm height on the basis of that we need to decide battery size of battery casing
Length of casing (L)= Number of cells at series * Cell diamter (26)+ margin at both side of cell (4)+ clearance at side (diamter of edged cell + margin)
B= 18*30+60
B= 600mm
Height of casing (H)= 65+35 (Height of cell + margin for wiring Cell, Holders and metal strips)
H= 100 mm
Weight of battery pack:
Cel Weight= 76g
Number of the cells= 2182
Battery pack weight (W)= Cell weight* number of cells + weight of accessories
W= 76*2182+45
= 165.8+4.5
= 170.3 Kg
Conculsion:
Lithium ion and Lithium Ion Polymer batteries are a great power source for some applications but they require preventive protection during discharging and charging