Project 1 Mechanical design of battery pack

Battery pack capacity: 18 kWh

Cell: ANR26650M1-B

Prepare a detailed battery pack drawing along with its enclosure.

Here we have to prepare detail of battery pack of having 18 kwh capacity

Here ANR26650M1-B cell is given which is rechargeable cell

So 1^st we download the data sheet of ANR26650M1-B cell

From above datasheet we understand cell specification which is are as follow

ANR26650M1-B Specifications

Nominal Ratings

• Voltage: 3.3 Volts
• Capacity: 2.5 Ah
• Energy: 8.25 Wh
• Specific Power: 2600 W/kg
• Impedance (1KHz AC Typical) 6 mº
• Cycle Life at 1C/1C, 100% DOD: > 4000 cycles
• Cell Type: 26650 Lithium Ion Power Cylindrical Cell

Discharging

• Max Continuous Discharage: 50 A
• Max Pulse Discharge Current >50% SOC (10s): 120 A
• Minimum Voltage: 2 Volts
• Temperature: -30°C to 55°C

Charging

• Recommended Standard Charge: 2.5 Amps
• Max Charge Rate: 10 Amps
• Max Pulse Charge Current <50% SOC (10s): 25 A
• Float Voltage: 3.45 Volts
• Recommended charge V & Cut-off Current: 3.6 Volts, taper to 125mA
• Temperature (reduce charging current to 250mA when under 0°C): 0°C to 55°C

Mechanical

• Diameter: Ø25.96 +/- 0.5 mm (1.0") Length: 65.15 +/- 0.5 mm (2.6")
• Mass: 76 g

For design the battery here we have to find mechanical and electrical parameter of cell with the help of above given parameter

Solution:-

Required battery pack capacity=18kwh

here the mentioned cell data

Nominal voltage 3.3V

capacity is 2.5Ah

We assume its 120 V battery pack

So we have to find capacity of battery pack

Capacity in Ah= power/ volt

capacity in Ah=(18*1000)/120

capacity in Ah=150 Ah

Now calculating series and parallel combination of battery pack arrangement

So for series combination = Total voltage / Nominal voltage

For series combination =120/3.3

= 36.36 similar to 37

So for series combination 37 cell required

Now calculate cell required for parallel combination

Parallel combination = total capacity / nominal capacity

Parallel combination =150/2.5

To get the required 150 Ah we need 60 parallel cell series

So calculating total no. of cell required in battery pack

Total no. of cell in pack = No. of cell in series * No. of cell in parallel

Total no. of cell in pack =37*60

Total no. of cell in pack =2220 Nos

For battery pack we have to find area and volume of pack

calculating mass of the battery pack

mass of the battery pack =total no. of cell * each cell mass

=2220*0.076

=168.72 kg

calculating Volume of pack

Volume of pack=total no. of cell * each cell volume

= 2220* 3.14*0.013^2*0.065

= 0.0765742 m^3

calculating Cell peak current

Cell peak current = max. pulse charge current * single cell capacity

=20*2.5

=50 A

calculating Battery pack peak current

Battery pack peak current = total no. of cell in series * each cell peak current

= 37*50

=1850 A

calculating Cell continuous current

Cell continuous current = max. continuous charge current * single cell capacity

= 10*2.5

25 A

calculating Battery pack continuous current

Battery pack continuous current = total no. of cell in parallel * each cell continuous current

= 25*60

= 1500 A

let assume the vehicle range is 140 km

Average energy of vehicle = 18000/140 km= 128.57 take 129 wh/km