Project 1 Mechanical design of battery pack
Aim- Project 1 Mechanical design of battery pack
Main Objective-
Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.
Battery pack capacity: 18 kWh
Cell: ANR26650M1-B
Here I took the ANR26650M1-B cell which is manufactured by LithiumWerks
ANR26650M1-B
Lithium Werks’ 26650 cells are best for Power.Safety.Life.™ applications. They deliver very high power due to their use of patented Nanophosphate® battery technology. Based on lithium iron phosphate chemistry (LiFePO4), the cells are inherently safe over a wide range of temperatures and conditions. Whether the application requires outstanding cycle life or stable float reliability, the Lithium Werks’ 26650 cells are suitable for a wide variety of power, pulse, or stand-by applications.
Nanophosphate® Technology 26650 Lithium Ion Power Cell Nanophosphate® battery technology offers thermal-stable chemistry, faster charging, consistent output, low capacity loss over time, and superior total cost of ownership (TCO). It provides the foundation for safe systems while meeting the most demanding customer requirements. Multiple layers of protection are employed at the chemistry, cell and system level to achieve an energy storage solution with superior safety and abuse tolerance compared to metal oxide lithium-ion chemisteries.
Applications
• Energy storage
• Frequency regulation
• Uninterruptible Power Supplies
• Communication technologies
• Aviation/Aerospace
• Electrified mobility devices
• Industrial equipment
• Medical devices
• Consumer Products
Required energy capacity of the battery pack 18 kWh
Cell used for the battery pack ANR26650M1-B
Cell Parameters used for the design process
Nominal cell voltage- 3.3V
Cell capacity- 2.5Ah
Individual Cell weight- 76g
Individual cell energy- 8.25Wh
Cell diameter- 26mm
Cell height- 65mm
Cost of each cell- 6.55$
Given capacity of battery pack- 18kWh (18000Wh)
Assuming the total voltage of the battery pack- 180V
Calculation for the design and contruction of battery pack.
pack capacity (Ah) = energy capacity(wh)/pack voltage
`Cp=18000/180=100Ah`
total no. of cells in parallel = pack capacity/individual cell capacity
`Np=100/2.5=40`
total no. of cells in series = pack voltage/individual cell voltage
`Ns=180/3.3=54.54=55`
total no. of cells = no. of series cells * no. of parallel cells
hence, total no. of cells`=40*55=2200`
total energy`=2200*8.25=18150Wh=18.15kWh`
Here if we want to get the voltage of 180V and capacity of 100Ah for this cell we have to connect the total cell of 2200 cells in 55s40p configuration
Thus the battery model is said to be 55s40p configuration (55 series and 40 parallel connections), which gives us 2200 cells. From this we can create overall capacity of battery pack as 18.15kWh which is slightly higher than 18kWh having total pack voltage of 180V and capacity of 100Ah. It means that this battery pack will provide 100A of current for 1 hour. Here connection are done were 55 cells are connected in series which makes a module and 40 number of that module is connected in parallel to make the full battery pack.
Enclosure Design
Calculation for enclosure dimension and volume of the above constructed battery pack
Cell diameter- 26mm
Cell height- 65mm
Individual Cell weight- 76g
Note- For the construction of the battery pack some space should be left vacant inside the inclosure for the BMS whereas space between each cell for connecting wires or connectors.
Length of enclosure = (No. of cells in series x cell diameter) + (some extra space)`=(26*55)+ 66=1496mm=1.496m`
Breadth of enclosure = (No. of cells in parallel x cell diameter) + (some extra space)`=(26*40)+ 40=1080mm=1.08m`
Hight of enclosure = Height of the battery + 4mm(extra space)`=69mm`
area of the pack `=1.496*1.08=1.615m^2`
volume of the pack`=1.496*1.08*0.069=0.11148m^3= 111.48`ltr
Mass of the total battery pack including the enclosure `=(76*2200)+20000 = 187200gms=187.2kg`
Specific energy density = pack energy capacity/weight of the battery pack `=18000/187.2=96.153`Wh/kg
Volumetric energy gensity = pack energy capacity/volume of battery pack`=18000/111.48=161.463`Wh/ltr
Reference - Datasheet for ANR26650M1-B (LithiumWerks)