Project 1 Mechanical design of battery pack

Aim

Battery pack capacity: 18 kWh

Cell: ANR26650M1-B 

Prepare a detailed battery pack drawing along with its enclosure. State your assumptions.

Nanophosphate® High Power LithiumIon Cell
ANR26650M1-B

A123’s high-performance Nanophosphate® lithium iron phosphate (LiFePO4) battery technology delivers high power and energy density combined with excellent safety performance and extensive life cycling in a lighter weight, more compact package. Our cells have low capacity loss and impedance growth over time as well as high usable energy over a wide state of charge (SOC) range, allowing our systems to meet end-of-life power and energy requirements with minimal pack oversizing.

Stages of assembling

Overview of lithium ion battery pack assembly storage

COMMERCIAL SOLUTIONS
Advanced lead acid replacement batteries for:
. Datacenter UPS
. Telecom backup
. IT backup
. Autonomously guided vehicles (AGVs)
. Industrial robotics and material handling equipment

GOVERNMENT SOLUTIONS

.  Military vehicles
.  Military power grids
. Soldier power
. Directed energy

GRID SOLUTIONS
. Frequency regulation
. Renewables integration
. Reserve capacity
. Transmission and distribution

TRANSPORTATION SOLUTIONS
Hybrid, plug-in hybrid and electric vehicle battery systems for:
.Commercial vehicles
. Off-highway vehicles
.Passenger vehicle

Constant power Discharge Characteristics

2.5C Constant Current Discharge
at Various Temperatures

Cycle Life Performance, 100% DOD, Various Temperatures and Discharge Rates

cell

Module

BMS allows protecting the batteries from outsides of its safe operating area, monitoring state, calculating secondary data.

Mechanical Design of Battery pack

The high voltage battery is one of the very important  component of battery electric vehicle.Tha parameters  have significant influence on the other component like

maximum traction motor torque

Maximum regeneration brake torque

Vehicle range

vehicle total weight

Four important parameters i am considered for electric vehicle battery design

1. chemical nature

2. voltage 

3. energy consumption on driving cycle

4. Range

Battery consist of 5 major parts

Anode

Cathode

Seperator

Terminals

Electrolyte

Different Form factor of cell are

Battery Calculation

Energy given- 18kwh

Voltage assumed= 400v

From the given reference voltage no of cells to be calculated

No of cells = Battery Energy/ ( Nominal voltage * Current Capacity)

No of cells= 18000w/(3.3*2.5)= 2182

Hence 2182 cells are needed to make a battery pack which compute the energy of 18000watt hour.

Next step is to configure the series parallel configuration. As in the series connection voltage gets added up.And in parallel configuration voltage remains same and capacity gets inceased.

Here we have assumed total of 400volts  to design a complete battery pack.

Rating of per cell is

Volatge =3.3v

current= 2.5A

No of series cell required= Total battery voltage/ voltage of each cell

No of cell= 400/3.3=121.21=122

122 cells are needed to connect in series which will give 400v.

Now the no of cell to connected in parallel= Total no of cell / No of cell in series

 parallel no cell= 2182/122=17.8= 18 cells

So now the battery configuration is 122 series cell *18 parallel cell

2. Battery Capacity

= No of cell * current rating of each cell

= 18*2.5A= 45Ah

3.Current supplied by the battery

45Ah means 45 ampere can be withdrawn  for one hour with one C rating

4. Range

Assuming that powertrain is 70% energy efficient = 100wh/km

Range= Total capacity/ energy consumed per km

range= 18000/100= 180 km

with the given current parameters assumed the range of the electric vehicle is 180km.

5. Battery Dimension

 Mechanical design

length of casing= no of cell in series * (cell diameter+margin both side + clearance)

= 122*(30+60)

=3720mm

Breadth of the casing is given by

= no of cells in parallel *(cell diameter + margin both side +clearances)

= 18*(30+60)

= 600mm

Height of the casing is given by

= 65+ 35( height of cell +margin for wiring)

=100mm

Weight of batterypack

per cell weight= 76g

no of cells= 2182

Total Weight= weight of each cell * no of cells + weight of accessories

= 76*2182+4.5= 170.3 kg

Battery pack construction

Voltage and capacity

series string

Parallel string

Cells combined parallel  can give rise to ampere capacity by connecting like polarity terminals.

Detailed flowchart for Li-ion battery pack assembling with Cylindrical cells:

 Conclusion

THe  cylindrical cell has high specific energy, good mechanical stability, and lends itself to automated manufacturing. Cell design allows added safety features that are not possible with other formats. it cycles well, offers a long calendar life, and is low cost, but it has less than ideal packaging density. The cylindrical cell is commonly used for portable applications.