The Internal Resistance of a Battery Formula- Introduction and Calculation

Internal resistance is one of the important factors that define the efficiency of the battery. Internal resistance is the amount of opposition that is caused by the flow of current. It is offered by the cells and batteries as a response to the current flowing in them. 

The internal resistance of the battery is measured in Ohms. It can also be defined as electronic resistance and iconic resistance, depending upon the type of resistance the battery is providing. 

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Many factors affect the resistance of the battery. Electromotive force and the battery are also closely related to the internal resistance of the battery. It is often seen that when we connect a load across the battery, a drop in the voltage of the battery occurs. This drop in the voltage is due to the internal resistance in the battery. 

If you want to calculate the battery's internal resistance, it is recommended to take the readings with an open circuit and when the battery is attached to a load. It will provide you with the correct information about the internal resistance of the battery. 

The Right Formula for Calculating the Internal Resistance of a Battery

It is very easy to calculate the internal resistance of the battery. 

Simplest Formula 

You have to use a common formula among all regions when it comes to calculating the internal resistance of a battery. The simplest formula which is in use is e = I (r + R). When you are calculating the internal resistance in a battery, it is recommended to consider the potential difference between the battery's terminals.  

Factors Affecting Internal Resistance 

You also have to calculate electromotive force. In the given formula, e is the electromotive force denoted by the current I flowing across both the terminals of the factory. R and r denote the internal resistance across both terminals. 

By solving the above formula, you can find the correct value of internal resistance present in any battery. This formula applies to all the cases. However, it can be rearranged according to the condition and situation have given by the battery.  

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Heat Energy Due to Internal Resistance 

Electrons are moving in the battery all the time. Due to the battery's internal resistance, some of the electric energy is converted into heat energy. Whenever you see your battery getting heated up after a specific time, this is because of the battery's internal resistance. 

Alternative Formulas 

You can also use other formulas for finding the internal resistance in the battery, including e – V = Ir. you can use this formula when the electromotive force and voltage are given while you have to calculate the value of current and resistance in the battery. 

Rearrange According to the Condition 

You can also use the formula (e – V)/I = r. This can be the case if you want to calculate the resistance to one of the terminals of the battery. It is upon you to regenerate the formula according to the situation given. 

How do you calculate the internal resistance of a battery?

It is very easy to find the internal resistance of a battery.  

Connect the Terminals of the Battery 

The easiest method to find the internal resistance of the battery is to connect terminals of the battery with a load. It can provide you with the correct information about the internal resistance of the battery.

Use the Formula 

You can also use the above-mentioned formulas to find the internal resistance of the battery. You have to know two values for every formula in order to find the internal resistance provided by the battery. You can use any of the above-mentioned formulas depending upon the situation given to you. 

Compare Open and Closed Circuits. 

There are multiple ways to calculate the internal resistance of the battery. 

Examine the Drop in Voltage 

If you want to calculate it practically, there are many ways. You can check the open circuit thoroughly and note the voltage of the battery. As soon as you connect a battery with any of the loads, you will see a sudden drop in the voltage.

This drop in the voltage is because of the internal resistance of the battery. You can calculate the internal resistance from the drop in the voltage of the battery. If that voltage drop is higher, that means the battery has a higher internal resistance. However, if the voltage drop is not much higher, it means the battery does not contain enough internal resistance.  

Performance of the Battery 

There are many other practical methods you can use to calculate the internal resistance of the battery. The performance of the battery will also tell you a lot about its internal resistance. Internal resistance for each battery is very important in order to keep the balance between both terminals of the battery. 

How do you find internal resistance?

The internal resistance of the battery can be found by applying the formula to calculate the internal resistance of the battery. 

Use the Formula 

The formula can be arranged according to the quality of the battery you want to calculate. You can also use any of the practical methods that are already mentioned in the above text

Use the Practical Method.

There are two ways to calculate the internal resistance of the battery. You can calculate it theoretically if you know the values for it. You can also use practical methods to examine the internal resistance present in the battery. 

Conclusion

Some of the methods which are effective in finding the internal resistance of the battery are discussed in the above-mentioned text. You can find an accurate internal resistance of the battery if you are vigilant enough to know the exact values. 

You can use a formula as well as use practical methods to get an authentic number for the internal resistance. The internal resistance is always between both terminals of the battery. You need to get this basic knowledge about the batteries before using them in a good way.