Cell:

An electric cell is a device, which converts chemical energy into electrical energy. It has two terminals, which are made up of metal: one terminal is positive ( ), while the other one is negative ( ). When the two terminals are connected to an electrical device, electric current flows through it.

cell : ANR26650M1-B specifications

calculations are made with some assumptions

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

Calculation as per assumptions:- 18kWh Battery Pack

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 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)

= 2.6 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

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 18120.96 Wh (For better and accurate calculation here I change kWh)
Now,
We will calculate per km average energy = 18120.96 / 250
= 72.483 Wh/km

Therefor,
Battery Pack total energy = Average energy x km
= 72.483 x 250
= 18120.96 Wh or 18.120 kwh

Let’s assume Nominal voltage for series connection = 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 connected in series x Single-cell energy

= 44 x 8.58 wh

= 377.52 wh

-- Number of cells connected 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

=48x44

= 2112

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.

-- 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
=52X48
= 2496 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
= 2496 A x 145.2
= 3624192 or 362.42 W

-- 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 48

= 1248 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

=1248 x145.2

= 18120.96 or 18.120 Kwh

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.

Detailed battery pack drawing along with its enclosure.

Different types of cells:

Prismatic cell:

Prismatic cells are made up of many positive and negative electrodes sandwiched together leaving more possibility for short circuit and inconsistency. The higher capacity makes it difficult for the BMS to protect each cell from over charging and dissipating heat.

Cylindrical cell:

A cylindrical cell is a cell enclosed in a rigid cylinder can. Cylindrical cells are small and round, making it possible to stack them in devices of all sizes. Unlike other battery formats, their shape prevents swelling, an undesired phenomenon in batteries where gasses accumulate in the casing.

Cylindrical cells are commonly found in medical instruments, laptops, e-bikes, and power tools. These batteries are also used in Tesla vehicles. Other EV manufacturers employ prismatic cells

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 t

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

The most common battery enclosures are made from plastic materials that are resistant to alkaline solutions and have a high impact strength. Metal housings are sometimes used, but metal requires careful design and assembly to avoid shorting of the cells in the battery pack.

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.

Thermal management:

Battery Module:

Battery Module means a combination of components of a Battery System that includes at least the following components: a Battery Cell, battery management electronics for Battery Cell balancing, voltage and temperature measurement, and connectors

Cooling System:

Liquid cooling is the most popular cooling technology. It uses a liquid coolant such as water, a refrigerant, or ethylene glycol to cool the battery. The liquid goes through tubes, cold plates, or other components that surround the cells and carry heat to another location, such as a radiator or a heat exchanger

Battery Management System(BMS):

A Battery Management System (BMS), which manages the electronics of a rechargeable battery, whether a cell or a battery pack, thus becomes a crucial factor in ensuring electric vehicle safety. It safeguards both the user and the battery by ensuring that the cell operates within its safe operating parameters