Project 1 Mechanical design of battery pack

• ANR26650M1-B is the battery model used here

• high power and energy density combined with excellsent safety performance and extensive life cycling in a lighter weight
• cellss have low-capacity loss and impedance growth over time as well as high usable energy over a wide state of charge (SOC) range

• ANR26650M1-B Specifications Nominal Ratings Voltage:
• 3 Volts Capacity
• 5 Ah Energy
• 25 Wh Specific Power
• 2600 W/kg Impedance (1KHz AC Typical) 6 mΩ Cycle Life at 1C/1C, 100% DOD: > 4000 cycle
• Cells Type: 26650 Lithium Ion Power Cylindrical Cells
• Discharging Max Continuous Discharge: 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 Certifications Transportation: UN 3480 (UN38.3), CIQ Safety: UL 1642, IEC 62133
• The Lithium ion ANR26650M1-B is the next generation of A123 Systems’ pioneering 26650 cylindrical cellss, now with greater power and energy density and lower impedance.
• This versatile lithium ion cells is suitable for a wide variety of applications and system designs. Proven performance in the toughest conditions, combining durability, reliability, and safety, the ANR26650 cells offers an excellsent combination of price-performance.
• Cylindrical Cells Primary Applications:
• Portable high-power devices
• Stationary battery backup systems
• Grid stabilization energy storage systems
• Commercial truck and bus hybrid electric vehicles (HEVs)
• Lithium Ion Cells Benefits:
• Power: Over 2,600 W/kg and 5,800 W/L
• Safety: Excellsent abuse tolerance and environmentally friendly
• Life: Excellsent calendar life, 10X cycle life vs. conventional lithium ion
• calculation 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 it proper range and its depend on the voltage(V) and amp-hr capacity (Ah)
• single cells energy (Wh) [the value of a single cells energy is used to calculate the total energy of the battery pack]:
• single cells energy (Wh)= cells capacity(Ah)* cells voltage(V)
• = 2.5Ah *3.3V
• = 8.25 Wh
• single cells volume calculation:
• single cells volume = pi(r^2) *h
• = 3.14(0.013^2) *0.065
• = 0.03451 m^3
• single cells energy density:
• volumetric energy (Wh/m^3) = single cells energy / volume of each cells
• = 8.25Wh / 0.03451 m^3
• = 239.0611 Wh/m^3
• gravimetric energy (Wh/kg) = single cells energy / single cells mass
• = 8.25Wh / 0.076 kg
• =108.5526 Wh/Kg
• calculation of high voltage battery packfor design and calculation of battery pack here, i assume a vehicle to achieve 200km in 18 KWh battery pack also i assume 145.2nominal voltage for series connection.
• so, we assume that,vehicle range = 200 Km
• battery pack capacity = 18.1210KWh now,
• we will calculate per Km average energy requirement = 18120.96 (Wh)/200 (Km)
• = 90.60 Wh/Km
• therefore, battery pack total energy = average energy * km
• = 90.60Wh * 200km
• = 18120.96 Wh
• 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 cells = 145.2V/ 3.3V
• = 44 cells
• 44 cells will be connected in a series connection to provide a proper voltage.
• energy for battery pack (Wh) = number of cellss connected in series * single cells energy
• = 44* 8.25Wh
• = 363 Wh
• number of cells connected in parallel = battery pack total energy (Wh)/energy for battery pack (Wh)
• = 18120.96 Wh/363 Wh
• = 50 cells
• 50 cells will be connected in a parallel to provide a proper capacity power.
• battery pack total energy (Wh) = no. of cells connected in parallel * energy for battery pack
• = 50* 363 Wh
• = 18.150 KWh
• battery pack capacity (Ah) = no. of cells connected in parallel * single cells capacity (Ah)
• = 50*2.5 Ah
• = 125 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 * number of cells connected in series
• = 50*44
• =2200 cellss
• 2200 cells will be used to make a complete battery pack.
• mass of battery pack = total number of cells for battery pack * mass of single cells
• = 2200 * 0.076 kg
• = 167.2 kg
• 2 kg is the total weight of cells connected in parallel and series
• total volume of the battery pack = total number of cells for battery pack * volume of single cells
• = 2200 * 0.0345 m^3
• = 75.9 m^3
• 9 m^3 is the volume occupied by total cells used in battey pack.
• cells peak current(A) = C rate (max pulse charge current) * single cells capacity
• = 20* 2.5
• = 50A
• battery pack peak current(A) = cells peak current(A) * no. of cells connected in parallel
• =50*50
• = 2500A
• battery pack peak power(W) = battery pack peak current(A) * voltage of series connection
• = 2500 A * 145.2
• = 363 KW
• cells continuous current(A) = C rate (max continuous charge current) * single cells capacity
• = 10* 2.5
• = 25A
• battery pack continuous current(A) = cells continuous current(A) * no. of cells connected in parallel
• = 25*50
• = 1250 A
• battery pack continuous power(W) = battery pack continuous current(A) * voltage of series connection
• = 1250 A * 145.2
• = 181.5 KW
• The process outlined in this article will begin with taking the battery cells out of packaging.
• This article will discuss the fabrication process using the battery cells as the “raw material” in the battery pack fabrication process.
• These small individual cells are typically manufactured at other, specialized facilities and arrive at the automobile fabrication plant as completed products.
• This workflow is the vision for the vaulted Tesla Gigafactory in Nevada which will produce all the battery cells required for the Tesla’s automotive assembly facilities.
• The individual battery cells are simply metallic cartridges that contain an anode, cathode, and separator immersed in an electrolyte fluid.
• Before the cells can be assembled into modules, each cells undergoes checks within a specialized fixture.
• This process is essentially a “leak check” process to ensure that the electrolyte isn’t leaking from the cells and to ensure that no moisture intrusion occurs over the entire operational life of the battery
• While most people know what components comprise a traditional gasoline-powered automobile engine, they likely know little about the components or parts of an Electric Vehicle (EV) battery pack.
• This is understandable because EVs are still relatively new in the automotive marketplace, and the conception of how exactly a battery works is more difficult to understand when compared with the myriad of moving components that comprise internal combustion engines.

• These battery cells are assembled together in frames to form Battery Modules.
• These modules are then linked together via a myriad of electrical connections and enclosed in the Battery Pack which is assembled directly to the automobile frame.
• Initially it is required to know the energy requirement.
• Then with that information, number of cells required to be calculated.
• Then configure the cells in series and parallel according to desired voltage and capacity.
• Calculate the pack dimensions and weight for preparing the casing pr cells holder to the pack.
• Then Battery pack assembly by placing them in cells holder according to the configuration.
• And then connecting the cells in series and parallel with the help of nickel strips by spot welding.

• Connect the BMS to the pack.
• Set a suitable thermal management technique to the battery pack.
• Placing in a enclosure for protection

Conclusion:

The necessary details are explained