Project 1 Mechanical design of battery pack

AIM - To Prepare a Mechanical Design Of Battery Pack . 

Given - Battery pack capacity: 18 kWh , Cell: ANR26650M1-B . 

Theory - 

                                 

Lithium Werks’ 26650 cells are capable of delivering very high power due to its 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 battery technology offers  stable chemistry, faster charging, consistent output, excellent cycle life and superior cost performance. 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 chemistries.

                      

Applications - 

• Energy storage
• Uninterruptible Power Supplies
• Communication technologies
• Aerospace
• Electrified mobility devices
• Industrial equipment
• Medical devices
• Toys

DATASHEET - Cell: ANR26650M1-B

              

Assumption - 

Assuming battery pack voltage  = 120V 

From the above DATASHEET - 

Single Cell Voltage Capacity = 3.3 V 

Cell Capacity =   2.5 Ah  

also , it is given that we have to take,  Energy Capacity = 18kwh 

                                                                                 = 18000 wh

1). Finding the number of series cell - 

No. of Series Cell = Battery Pack Voltage /  Single Cell Voltage Capacity

                          = 120 / 3.3 

                          = 37 cells

2). Finding the number of cells in parallel - 

We Know That , 

Pack capacity = Energy capacity / Pack Voltage 

                    = 18000 V*A*h/120 V      [Since  , Watt(W) = Voltage (V) * Amphere (A) ] 

                    = 150 Ah 

So , No. of Parallel cell = Pack Capacity / Cell Capacity

                                 = 150 Ah / 2.5 Ah 

                                 = 60 cells 

3). Finding the total no. Of Cells - 

Total cells = No. of cells in series * No. of cells in parallel 

               = 37 * 60 

               = 2220 cells 

Mechanical Design Of Battery Pack - 

              

    

Given - : 

Length of each cell    = 26 mm 

Diameter of each cell = 25.96 mm 

Assuming,  Thickness of cell strips = 2 mm 

Width of battery pack (B) - 

B = no. of cells in series * diameter of each cell + (no. of cells -1)* thickness of strip 

B = 37 * 25.96 + (37-1)* (2 mm +2 mm ) = 1104.52 mm 

Length Of Battery Pack (L) - 

L = no. of cells in parallel *dia of each cell + (no. of cells in parallel-1)* thickness of strip 

L = 60 * 25.96 + (60 - 1) * (4) =  1793.6 mm

Weight Of Battery Pack - 

weight of one cell = 76 g

weight of battery pack = 2220 * 76 = 168720 g

                                 = 168.720 kg 

Area Of  Battery Pack (A) - 

A = Length of battery pack * Width Of battery pack 

A =  1793.60 *1104.52  mm^2  = 1.981 m ^2 

Volume of Battery Pack (V) - 

V = Area Of Battery pack * Height of battery pack 

V = 1.981 * 0.06515 = 0.129 m^3 

Specific Energy(s) - Specific energy or massic energy is energy per unit mass.

Specific Energy (s) = Battery Pack Energy/ Weight Of Battery Pack 

                        s = 18000 / 168.720 

                        s = 106.68 Wh/kg 

Battery Pack - 

                   

Module Circuit Diagram - 

 

 Graphs Related To Cell Data - 

   

Conclusion - 

• Mechanical design of battery pack has been done . 
• Battery Pack drawing has been made . 
• Circuit diagram of battery pack module also have been made. 
• Assumption taken also been highlited .