Project 4
PROJECT 4:-
For a vehicle with a gross weight of 300 kg, the motor ratings are 1200Wh, and 65V. The range is 225km and the maximum speed is 60kmph. Calculate the capacity of the battery pack required and the number of series-parallel connections. Give a stepwise discussion on how a battery pack is built.
SOLUTION:-
We have to Do calculation part for the find the battery [ack capacity for this Given Data
Given Data are,
Vehicle weight=300kg
Motor rating=1200wh,65V
Range=225km
Max speed=60kmph
We know that, calculate the Motor current
Power(P)=Voltage(V)*Current(I)
1200=65*1
I=1200/65
I=18.46 A
Current with drawn back Motor 18.46 Amp
Assure current loss 1-10%
After loss new motor current 18.46*1.05=18
=19.38 Amp
Now Calculate the Power required at max speed
At 60kmph
Power=Voltage*Current
Power=65*19.38
Power=1260 watt
Then We have to calculate travel Factor
Travel factor=Total Range /Total Speed
=225/60
Travel Factor=3.75
To calculate Power based on travel factor
Power requried=Power*Travel Factor
=1260*3.75
=4.7kw
Then we have to calculate battery pack capacity based of efficiency
we take Battery pack efficiency 85% to 95%
we take 85%
Required Battery Pack Capacity =4.7/5.52 kw
Then we Calculate,
Battery pack efficiency based on motor efficiency
Total Battery Pack Capacity = 5.52/0.85
=6.49 kwh
Now we have find how much connection comes in series and parallel
>Series connection
Motor Voltage 65 V
Cell voltage 3.7 V
No of series cells 65/3.7=18
18 cells in series
>Parallel connection
Motor current 19.38/2.8=7
7 Cell in Parallel
This all are the calculation part of Battery
Now we see how to developed Battery Pack First we have to select cells type then size of cells
Step to built the battery pack:
>we have to decide the output voltage. In my case, I require 65V. As we all know 126 cells provide a nominal voltage of 3.7V so after a bit of calculation we will need 18 cells in series and 7 cell in parallel to get the output.
>here are links to some good quality cells and charger,
>we need to make sure all the cells have the same voltage. If not charge
>I don't have a spot welder so I'm using good old soldering method. However, soldering is not recommended because it heats up the cells
>For the soldering process, I'm using 2.5 Sqmm wire of which I made about 1 inch long pieces which will be used later-on to connect the cells in series and also do not forget to pre-tin them as well.
we to use a any metal object and scratch all the terminals of the batteries you want to connect. After scratching, put a small quantity of flux on the cell terminal and affix a little bit of solder on the terminal. Cell holders give your battery pack an element of vibration resistance Do the same for the nickel strip and connect the Nickle strip with the terminal of the cell.
And that's it our battery back is complete!