Project 1 Mechanical design of battery pack
PROJECT 1
aim:
to Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.
software used::
matlab R2020a
required::
the datasheet of the below battery is attached in the files.
from the data sheet,
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 mΩ
Cycle Life at 1C/1C, 100% DOD: > 4000 cycles
Cell Type: 26650 Lithium Ion Power Cylindrical Cell
Discharging
Max Continuous Discharage: 50 A
Max Pulse Discharge Current >50% SOC (10s): 120 A
Minimum Voltage: 2 Volts
Temperature: -30ºC to 55ºC
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 250mA when under 0ºC): 0ºC to 55ºC
Mechanical
Diameter: Ø25.96 +/- 0.5 mm (1.0")
Length: 65.15 +/- 0.5 mm (2.6")
Mass: 76 g
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Calculation as per assumptions:- 18kWh Battery Pack::
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/m^3) = Single Cell Energy / Volume of each cell
= 8.58 Wh / 0.03451 m^3
= 248.62 Wh/m^3
Gravimetric energy (Wh/kg) = Single Cell Energy / Single Cell Mass
= 8.58 Wh / 0.076 kg
= 112.89 Wh/kg
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Calculation as per assumptions:- 18kWh Battery Pack(assumption)::
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 150 km. For this calculation, I assumed 158.4 V a nominal voltage for series connection.
Vehicle Range = 150 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 / 150
= 120.8064 Wh/km
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Let’s assume Nominal voltage for series connection = 158.4 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
=158.4 V / 3.3 V
= 48
48 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
= 48 x 8.58 wh
= 411.84 wh
-Number of cells connected in parallel
= Battery pack total energy (wh) / Energy for battery pack (wh)
=18120.96/411.84
= 44
44 cells will be connected in parallel to provide a proper capacity power.
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- Battery pack total energy (wh)
= No. of cells connected in parallel x Energy for battery pack (wh)
= 44 x 411.84
= 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
=48x44
= 2112
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from the above it is clear that totally 2112 batteries needed and the configuration of 48s44p.
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 m^3
This is the volume of2112 cells which are used in the battery pack system.
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-Cell peak current (A)
= C rate (Max Pulse Charge Current) x Single cell capacity
= 20 x 2.6
= 52 A
-Battery pack peak current (A)
= Cell peak current x No. of cells connected in parallel
=52X44
= 2288 A
It is used for the operation of the battery pack. By this way, a vehicle will decide how much power is required to move.
-Battery pack peak power (W)
= Battery pack peak current x Voltage of series connection
= 2288 A x 158.4
= 3624192 or 362.42 W
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-Cell continuous current (A)
= Crate (Max Continuous Charge Current) x Single cell capacity
= 10 x 2.6
= 26 A
-Battery pack continuous current (A)
= Cell continuous current x No. of cells connected in parallel
= 26 x 44
= 1144 A
This is the power which is supply continue to the whole battery pack system.
-- Battery pack continuous power (W)
= Battery pack continuous current x Voltage of series connection
=1144 x158.4
= 18120.96 or 18.120 Kwh
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detailed battery pack drawing along with its enclosure.
BATTERY HOLDER ,SPACER For CELL CYLINDRICAL LI-ION
A battery holder or a battery mount is an integrated or separate cavity to hold cells. If it is a separate compartment, it can be attached to a cell-powered device. It is used to hold the cells securely and power the device it is attached to.
A battery holder clip is a simple, economical choice for mounting batteries securely within a holder. They tend to consist of two metal arms, arranged in a loop with a small gap at the apex, through which the cells are pushed and subsequently held in place.
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.
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 pull through the busbars. The benefits are nearly limitless!
battery enclosure:
A battery enclosure is a box designed to protect batteries from potential weather and battery mishaps. They can be designed for indoor or outdoor use, and may include room for electronics. Specific designs allow for pole, wall, or ground mounted systems.Battery enclosures are essential components of off-grid solar systems for a number of reasons including: physical protection from outside elements including people and weather patterns, maintaining consistent temperatures, and meeting the requirements of the National Electric Manufacturer’s Association (NEMA)
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.
https://www.novelis.com/automotive/electric-vehicle-battery-enclosure/
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as we know now
Power (p)= Voltage (v) * Current (i) kw
3.3 *2.5 =8.25 kw
To get 18kwh ,we are assuming 48s 48p
i.e; 48*48 =2304 cells
series connection 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 wth battery spacers to hold cells and for their connection nickel strip is used
when cells are connected by nickel strip spot welding should be used so that cell not get damage.
final form
the final form of battery pack is shown below.
cell---module----pack
collection of cell is module.
collection of module is battery pack.
here we see a four module on right side and four on left.
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referance::
1. https://www.sunwize.com/tech-notes/what-to-look-for-in-a-battery-enclosure-for-solar-systems/
2. https://www.thomsonreuters.com/en/reports/electric-vehicles/electric-vehicle-methodology.html
------------------------thank you---------------------------------------------------------------------