Project

Ans i

To meet req of motor (40 kW, 110V) and average peak power from battery (23 kW) Lithium-ion (Li-ion) cells is to be chosen.
It has below Advantages-
1. high energy density
2. high voltage per cell
3. compact in size
4. low maintenance
5. available in different chemistries

List of thermal components used for the cells are:
1. CID - for protection during overcharging conditions
2. Fuse - for protection during over-current conditions
3. PTC - for protection during external shock conditions
4. PCB - for protection during over-discharging conditions

Ans ii

Info from datasheet-
1. nominal capacity = 4 Ah
2. dimensions - dia = 18 mm, height = 65 mm
3. weight = 45 gm
4. nominal voltage = 3.6 V
5. internal resistance = 0.2 Ohm 

Ans iii

As Power = voltage*current,
req motor current = 23000/110 = 209.09 ~ 210 A.
So, Number of cells in parallel = 210/4 = 52.5 --> 53

As motor voltage = 110 V and cell nominal voltage = 3.6 V
So, Number of cells in series = 110/3.6 = 110/3.6 = 30.55 --> 31

Total number of cells for the battery pack = Number of cells in parallel * Number of cells in series = 53*31 = 1643.

Ans iv

Volume of the battery pack = volume of 1 cell * total number of cells = [pi/4*(0.018)*(0.018)*(0.065)] * 1643 = 0.027 m3  

Ans v

weight of the battery pack = weight of 1 cell * total number of cells = 0.045 * 1643 = 73.935 kg

total energy of the battery pack = nominal Capacity per Cell * Nominal Voltage per Cell * Number of Cells = 4 * 3.6 * 1643 = 23.66 kWh

Ans vi

To establish cell-to-cell interconnection spot welding can be used

Ans vii

Tests for mechanical stability-
1. vibration test
2. shock test
3. waterproof test

Tests for safety-
1. fire resistance test
2. over-discharge test
3. short-circuit test
4. overcharge test

Ans viii

Recycling process-
1. Pryo Process- Recycling at the Refining Stage
2. Hydro Process- Recycling at the Production Stage
3. Direct Process- Recycling at the Assembly Stage

Ans ix

Reasons of thermal runaway-
1. manufacturing defect
2. high temperature
3. short circuit
4. overcharging

To prevent thermal runaway-
1. quality manufacturing
2. storage in hazard free area, good thermal management system, good BMS
3. use of fuse
4. avoid overcharging