# What is Internal Resistance, and how is it calculated?

Internal resistance in a battery refers to the amount of resistance that the battery's internal components, such as electrodes, electrolyte, and terminals, present to the flow of current within the battery. This resistance causes some of the electrical energy produced by the battery to be converted into heat, reducing the amount of available voltage and current that can be delivered to an external circuit.

The internal resistance of a battery can be calculated by measuring the voltage drop that occurs when a known current is drawn from the battery. This is known as the load voltage, and it can be measured using a multimeter or other electrical measuring device. The internal resistance can then be calculated using Ohm's law, which states that resistance is equal to voltage divided by current:

Internal resistance = (Open circuit voltage - Load voltage) / Load current

Where the open circuit voltage is the voltage measured across the battery terminals when no current is being drawn from the battery, and the load current is the current being drawn from the battery when the load voltage is measured.

It's worth noting that the internal resistance of a battery can vary depending on factors such as the age and condition of the battery, its temperature, and the load being applied to it. Additionally, the internal resistance of a battery can be affected by the type of battery chemistry used, such as lead-acid, lithium-ion, or nickel-metal hydride.