Project

ii.) Look for a relevant datasheet and note the cell nominal capacity, dimensions, weight, nominal voltage, internal resistance for the chosen cell.

Nominal capacity  = 2600 mAh

Nominal voltage = 3.7

Dimension  = diameter : 18.4mm, H =65.2mm

Weight = 46.5kg

Resistance = 70m ohm

 

iii.) Calculate the total battery pack voltage, current. Find the total number of cells for the battery pack. Also calculate the maximum power transfer from the battery.

Motor : 40kW, 110V, current = 363 A

Peak power = 23 kW

No of series connection = 110/3.7 = 29.7 `= 30

No of parallel connection = 36.3/2.6 = 13.9`= 14

Total number of cells = 30*14 = 420

 

iv.) Estimate the volume of the battery pack(BMS, conductors can be excluded).

Volume = Diameter * H

  = 18.4*65.2 = 1199

 

vi.) Define the cell-to-cell interconnection method to be used here.

Spot welding:

<!-- [if !supportLists]-->è <!--[endif]-->Short pulse of high current is passe through the 2 metal pieces and melt together to make a connection.

<!-- [if !supportLists]-->è <!--[endif]-->Nickel strips of bus bars are used

<!-- [if !supportLists]-->è <!--[endif]-->Bus bars coated with copper have better thermal conductivity.

vii.) What are the tests that you would perform for the battery mechanical stability and safety?

Various test that can be done to confirm the mechanical stability and safety are:

<!-- [if !supportLists]-->-       <!--[endif]-->Cell short circuit test

<!-- [if !supportLists]-->-       <!--[endif]-->Nail penetration tests

<!-- [if !supportLists]-->-       <!--[endif]-->Cell overcharge test

<!-- [if !supportLists]-->-       <!--[endif]-->Fire resistance test

<!-- [if !supportLists]-->-       <!--[endif]-->Shock test

<!-- [if !supportLists]-->-       <!--[endif]-->Vibration test

<!-- [if !supportLists]-->-       <!--[endif]-->Water proof test

 

viii.) Consider the battery pack ages after a period of time and cannot be used anymore, state the recycling process.

Types of recycling:

<!-- [if !supportLists]-->-       <!--[endif]-->Pyro process  : Sending the battery directly to refining company or mining field.

<!-- [if !supportLists]-->-       <!--[endif]-->Hydro process: Separating the components of the battery and send to the cathode or anode manufacturing company

<!-- [if !supportLists]-->-       <!--[endif]--> Direct recycling: Sending the battery pack to manufacturing company

 

ix.) State the reasons of thermal runaway and how can it be prevented.

As the battery heats up, the resistance to the charging current is decreased, due to which it allows more current to flow and creates more heat. This results in thermal runaway.

<!-- [if !supportLists]-->è <!--[endif]-->Always check for faults and short circuits

<!-- [if !supportLists]-->è <!--[endif]-->In case of overheating disconnect from charging.

<!-- [if !supportLists]-->è <!--[endif]-->Replace old batteries

<!-- [if !supportLists]-->è <!--[endif]-->Maintain proper air temperature.