ABSTRACT: In this project, we are going to calculate the all parameters which are required for the build EV battery pack. We are going to use the Cell: ANR26650M1-B for our battery pack. In parameters, we will consider all electrical aspects like temperature, Depth of discharge, Operation current, Energy density, , Battery capacity, , Ampere-hour (Ah) Capacity. We also calculate all geometrical considerations like size, weight, volume, area, etc. In the end, we consider some enclosures model for our battery pack.

OBJECTIVE:

1) Collecting the data of Cell: ANR26650M1-B from Nanophosphate High Power LithiumIon Cell PDF.

2) Calculating all Electrical parameters for 18 kWh Battery Pack.

3) Calculating all Physical dimensions for Battery Pack.

METHODOLOGY:

1) To build the Battery pack for any Electric Vehicle, we have to calculate the first proportion of power then motor power, and depend on that we will model the battery pack so we know how much power we required which is 18kWh.

2) For the 18kWh battery Pack we have to calculate how many cells are parallel and how many cells are in series.

3) After calculation of series and parallel combination we have to calculate the proper Geometry and topology consideration for assembling batteries.

PROCEDURE:

1) first we have to start with Cell calculation.

2) Then we will do Battery Pack assumptions.

3) After assumptions, we have to do Battery pack calculations.

4) from Cell Dimensions we calculate the surface required for a battery pack.

5) Depending upon the above calculations we build Battery Pack construction.

Followings are the all cell (Cell: ANR26650M1-B) parameters for battery pack:

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

Cell dimensions:

Cell calculation:

1) Volume of the cell: For the calculation of the volume of the cell we use the formula of Volume of cylinder.

From Datasheet of Cell, we have 'r' and 'h' values

r=0.013m and h=0.065m = Volume of the cell: Pi*r^2*h

: 3.14⋅0.0132⋅0.0653.14⋅0.0132⋅0.065

:0.0000344929m^3

The volume of the cell is 0.0000344929m^3

Basically, the value of the volume of the cell is used to find out the total volume of the battery pack.

Cell Energy= Cell Capacity (Ah) × Cell Voltage (V)

= 2.5 × 3.3

= 8.25 Wh

Cell Energy is 8.25 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/m³) = Single Cell Energy / Volume of each cell

= 8.25 Wh / 0.0000344929m³

=2,39,179.6572 Wh/m³

Gravimetric energy (Wh/kg) = Single Cell Energy / Single Cell Mass

= 8.25 Wh/ 0.076kg

= 108.553 Wh/kg

^{Single Cell Energy Density is 2,39,179.6572 Wh/m3}

Battery pack calculation

Assumption

1. The range from 18 kWh battery pack =100 km

2. Battery pack voltage = 72 volts

So number of cells in Series= Total voltage / nominal cell voltage

= 72 / 3.3 =21.81

^{Rounding off to 22}

For calculating number of parallel cells we need the Total charge(Ah) of battery pack

Charge = 18000/ 72= 250 Ah

so number of cells in parallel = charge / nominal cell capacity

= 250/2.5

= 100

So the configuration is 22S100P

Total number of cells = 22*100

=2200

Actual Voltage of battery pack = 22*3.3= 72.6 V

Actual Battery pack capacity= 72.6*250= 18150kWh

Total volume = no of cells * Volume of single cell

= 2200 * 0.0000344929

=0.07588438m³

Total volume required for battery pack is 0.07588438m³

^{Weight of battery pack}

We also have single cell weight from that we can calculate the total weight of battery pack without other mechanical and electrical connections.

Weight = No of cells * weight of single cell.

= 2200 * 0.076kg

= 167.2kg

Weight of battery pack is 167.2kg

Energy density

Energy density= Battery pack energy / Volume of the battery pack

= 18150 kWh / 0.07588438

= 239179.65726279

=239.18kWh/m^3

Energy consumption /km = 18150 Wh/100km

= 181.5Wh

Cell peak current (A)

Cell peak current = C rate (Max Pulse Charge Current) x Single cell capacity
= 20 x 2.5
= 50 A

Battery pack peak current (A)

Battery pack peak current = Cell peak current x No. of cells connected in parallel
=50X100
= 5000 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
= 5000 A x 72.6
= 3.63 kW

Detailed battery pack drawing along with its enclosure.

SERIES AND PARALLEL ARRANGEMENT OF CELL

Battery holder

Nickel Strips

To make the battery pack, you have to connect the many cells together by means of Nickel strips or thick wire. Generally, Nickel strips are widely used for this. In general two types of nickel, strips are available in the market: nickel-plated steel strips and pure nickel strips. I will suggest buying a pure nickel. It is a little bit costlier than nickel-plated steel, but it has much lower resistance. Low resistance means, less heat generation during the charging and discharging, which leads to longer useful battery life.Nickel strips come with different dimensions and lengths.

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

RESULT:

NO	Calculated Parameters	Value Get
1	Cell Volume	0.0000344929m^2
2	Cell Energy	8.25Wh
3	Cell Energy Density	239.18kWh/m^3
4	Pack Configuration	22s 100p
5	Total no of cells	2200
6	Voltage	72.6V
7	Capacity	250Ah
8	Energy	18150WAh
9	Total volume	0.07588m^2
10	Battery pack peak power (W)	3.63 kW
11	Weight	167.2kg