# Why Does a Battery Have an Internal Resistance?

Here, V is the voltage drop across the load (resistance) “R”. Additionally, there is a reduction in the amount of maximum current that can be drawn from a battery due to its internal resistance.

If the value of I > I(0), then the value of V becomes negative. This implies a negative R which is practically not possible. Therefore, one can conclude that if the circuit is short-circuited by directly connecting the two terminals with a wire, the maximum current that will be drawn is now limited to I(0).

The next thing is ‘power dissipation from a battery’. The presence of intrinsic resistance hints that a battery is not fully efficient at transferring its electrical power to an external circuit. A small amount of power is always dissipated in the form of heat and gets wasted in the resistor present inside the battery.

This gives resemblance to the laws of thermodynamics which states – “no mechanical machine can use all input energy to do work without expending some energy on itself. This energy is the heat energy that increases the temperature of the machine.”