Question

A 12 volt battery in a motor vehicle is capable of supplying the starter motor with 150 A. It is noticed that the terminal voltage of the battery drops to 10 V when the engine is cranked over with the starter motor. Determine the internal resistance of the 12 volt battery.

Answer 1

`r=(1)/(75)` Ω≈0.01333Ω

Step-by-step explanation:

You can check the internal resistance model in the image I attached you.

Now using Kirchhoff's voltage law:

ε=
`Ir+IR` (1)

Where:

`IR=V_R=LoadVoltage=10V`

ε=12V

`I=150A`

Evaluating the data provide in (1)

`r=(12-10)/(150) =(1)/(75)`≈0.01333Ω