Project 1 Mechanical design of battery pack

From the ANR26650M1-B cell Data Sheet specifications following observations made:-

Assumptions :

Energy ( capacity ) = 18 Kwh

Voltage required to run system = 300 V

From Specification Data

Cell Nominal voltage = 3.3 V

Capacity = 2.5 A

Weight of cell = 76gms

1) Cell in Series = voltage required/Nominal voltage

= 300/3.3

= 90.9

= Aprox. 91 cells

2) Cells in Parallel = Total no. of cells / Cell in series

Total no. of cells = Energy / (Nominal voltage * Capacity)

= 18000/(3.3*2.5)

= 2181.8

= Apprx. 2182 cells

Hence cell in Parallel = 2182/91

= 23.97

= Aprox. 24

Therefore cells are joined in series are 91 and in parallel are 24.

Weight of the Battery pack considering only cell = Total no.cells * Weight of cell

= 2182*76

=165832

= 165.832 Kg

Design Conclusion:-

Cells in Series = 91 cells

Cells in parallel = 24 cells

Total No. of cells in a Battery pack = 2182 cells

Battery pack weight (considering only cells) = 165.832 Kg

Depend upon the design process joining and module packing is considered.

EXPLANATION ON BATTERY PACK ASSEMBLY

Battery

A collection of two or more cells which are connected in series is called A Battery. A battery is an energy source that converts chemical energy to electrical energy. It is otherwise known as Electrochemical Cell. The energy is stored in the form of chemical energy inside a battery. Batteries give us a convenient source of energy for energizing devices without cables and wires. When it is connected to a circuit it produces electrical energy. A battery consists of two terminals – A Positive and Negative Terminal. The positive terminal is called Cathode and the negative terminal is called Anode. They are also called as Electrodes of a Cell. These electrodes will be dipped in a solution called Electrolyte. It is liquid which is ionic and conducts electricity.

A simple cell

A 6 series and 10 parallel Battery pack example

Example Samples

SUMMARY OF JOINING METHOS OF CELLS:-

Joining methods	Advantages	Disadvantages
Resistance welding	Low cost Efficient and fully automated No filler metals or gases Existing technology for weld quality control	Difficult to produce large nuggets Difficult for highly conductive materials Electrode sticking/ wear Possible expulsions
Laser welding	Non-contact process Less thermal input – less distortion Very high precision of welding High speed	Hard to produce a large joint area Needs good joint fit-up Material reflectivity Need of shielding gas High initial cost
Ultrasonic welding	Solid state process Excellent for highly conductive materials Good for thin sheets or wires Good for multi-layered sheets Gauge ratio insensitive Dissimilar materials No filler metals or gases	Restricted to lap joints Limited in joint thickness (< 3mm) Challenging on high strength, hardness materials Sensitive to surface conditions Possible audible noise Large weld indentation
Mechanical joining	Ease disassembly No use of heat source	Added parts and mass Labor-intensive

Module level Joining

A simple six steps for battery Joining