Q1) 14.4 – 2x1= 12.4
Rin= 12.4/2=6.2 ohm
The equivalent circuit of a cell is shown in Figure (a). This circuit is useful when considering the various failure mechanisms and to show how the components affect the cell resistance. For example, the terminals, plate straps (paralleling bars), and internal interconnecting welds account for 44% of the total resistance. A somewhat simplified and more common representation of a cell is shown in Figure (b). This circuit is useful in battery and cell testing.
If the manufacturer provides detailed discharge curves for individual cells or for a general design covering various cell capacities, the cell internal resistance may be determined graphically. The internal cell resistance is the slope of the “initial volts” line in the discharge curve (this is not the same resistance that would be measured with an impedance tester).