Project 1 Mechanical design of battery pack
AIM: Mechanical design of battery pack
Objective:-
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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Solutions:-
Nanophasphate high power lithium ion cell ANR26650ml-B
A123's high -performance Nanophosphate lithium ion phosphate [LiFep04] battery technology delivers gigh 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 charge (SOC) range,allowing our systems to meet end-of-life power and energy requirements with minimal pack oversizing.
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 m ohm
cycle life at 1C/1C,100% DOD:>4000 cycles
cell Type :26650 Lithium ion power cylindrical cell
Discharging
Max countinuos Discharge:50 A
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 curent :3.6 volts,taper to 125 mA temperature
(reduce charging current to 250mA when under 0 C): 0 C to 55 C
Mechanical
Diameter :Pai 25.96+/-0.5 mm (1.0)
Length : 65.15 +/-0.5 mm (2.6 )
mass :76 g
calculations as per assumptions:- 18 kwh battery pack
calculation for designing an 18 kwh battery pack,basically 18 kwh 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 pcak for an electric vehicle to achieve its range upto 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)
=2.6x3.3
=8.58 wh
The value of a single cell is used to calculate the total energy of the battery pack.
single cell energy density
Volumentric energy (wh/m^3)=single cell energy / volume of each cell
= 8.58 wh/0.03451 M^3
=248.62 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 181210.96 wh (for better and accurate calculation here i change kwh)
now, we wil calculate per km average energy=18120.96/250
=72.483 wh/km
Therefore, battery pack total energy=average energy x Km
=72.483 x 250
=18120.96 wh or 18.120 Kwh
Lets assume nominal voltage for series conncetion=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 conncected 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 Ah
The 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 =48 x 44
=2112
2112 cells will be used to make a complete battery pack.
Mass of battery pack
=total no.of cells for battery 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 battery pack x volume of single cell
=2112 x 0.0345
72.89 m^3
this is the volume of 2112 cells which are used in the battery pack system.
Cell pack peak current (A)
=cell peak current x No.of cells connected in parallel
=52 x 48
=2496 A
it is used for the operation of the battery pack.by this way, a vehicle will decide how ,uch power is required to move.
Battery pack peak power (w)
=battery pack peak power (w)
= battery pack peak current x voltage of series connection
=2496 A x 145.2
=3624192 or 362.42 W
cell continuos current (A)
=crate (Max continuos charge current ) x single cell capacity
=10 x 2.6
26 A
battery pack continuos power (W)
=battery pack continuos current x voltage of series connection
=1248 x 145.2
=18120.96 or 18.120 kwh
Detailed battery pack drawing along with its enclosure.
Battery Holder ,spacer for Cell Cylindrical Li-ion:-
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 wont 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.
100% pure nickel strip.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 pill through the bus bars.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-efficient aluminium solution for mass production electric vehicles when compared to aluminium extrusion and casting-intense designs.
* Low price premium on $/kg saved compared to equivalent steel designs at substabtially lower weight.
as we know now
power (p)=voltage (V) * current (i) Kw
3.3 * 2.5 =8.25 Kw
to get 18 kwh,we are assuming 48s 48p
i..e; 48*48=2304 cells
series coonection gives 48 *3.3=158.4 v
parallel connection gives 48 * 2.5=120 A
from this we can get
158.4 *120=19.008 kwh energy or capacity.
we design battery pack for 48s and 48p cell along with battery spacers to hold cells and for their connection nickel strip used
when cells are connected by nickel strip spot welding should be used so that cell not get damage.
Final form:-
