Project 4
Calculation of Battery Pack Capacity:
Given:
vehicle weight - 300 kg
Motor ratings - 1200wh,65v
Range -225km
Max speed - 60kmph
To Calculate Current :
Power = v*I
I = 1200/65
=18.46 A.
Assume loss =1-10%
after the loss of motor current = 18.46*1.05
= 19.38 A
To calculate the power required at max speed:
At 60km/hr power = voltage * current
=65* 19.38
=1259.7 W
To Calculate Travel Factor:
Travel Factor = total range / total speed
=225/60
= 3.75
To calculate power based on Travel Factor:
power requires = power * travel factor
=1259.7 * 3.75
= 4723.8 Watts = 4.7 KW
To calculate Battery pack capacity based on efficiency:
Battery pack efficiency =85 - 95%
we consider 85% =4.7/0.85
=5.5KW
To calculate battery pack capacity based on motor efficiency:
Total battery pack capacity = 5.5/0.85
=6.4KWh
To calculate series connections:
Motor voltage = 65 V
Cell nominal voltage = 7.2
No of series cell = 65/7.2
=9
Parallel connection
Motor current = 19.38
cell current =5.4
parallel connection = 19.38/5.4
=3
Steps for Building Battery Pack:
*As per the above calculation we have to use 9 cells in series and 3 cells are in parallel, do the parallel connection first and then connect all parallel connected cells in series
*But before connecting them we have to check all are in balanced condition or not
*After placing cells in the cell holder do the series-parallel connection
*For connection use a nickel strip and connect the nickel strip to the cells or battery pack use spot welding (if you do not have spot welding then use the soldering method but it is not recommended because it produces more heat).
*Connect the Battery management system (BMS) to a battery pack.
*Measure the voltage across BMS and check required voltage is getting or not.
*After that enclose the battery pack by the sheet for safety purposes.