Enter the battery current (amps) and the battery resistance (ohms) into the calculator to determine the Battery Voltage. 

Battery Voltage Formula

The following formula is used to calculate the Battery Voltage. 

Vb = Ib * Rb


  • Where Vb is the Battery Voltage (volts)
  • Ib is the battery current (amps) 
  • Rb is the battery resistance (ohms) 

To calculate the battery voltage, multiply the battery current by the battery resistance.

How to Calculate Battery Voltage?

The following two example problems outline the steps and information needed in order to calculate the Battery Voltage.

Example Problem #1:

  1. First, determine the battery current (amps). In this example, the battery current (amps) is measured to be 105.
  2. Next, determine the battery resistance (ohms). For this problem, the battery resistance (ohms) is calculated to be 3.
  3. Finally, calculate the Battery Voltage using the formula above: 

Vb = Ib * Rb

Inserting the values from above into the equation yields: 

Vb = 105 * 3 = 315 (volts)


What factors can affect battery voltage?

Battery voltage can be affected by several factors including the state of charge of the battery, the temperature of the environment, the age of the battery, and the load applied to the battery. Higher temperatures can increase voltage slightly, while colder temperatures can decrease it. As a battery ages, its internal resistance may increase, leading to a potential drop in voltage under load.

How do you measure battery resistance?

Battery resistance can be measured using a multimeter or a specialized battery resistance tester. The measurement involves applying a known load to the battery and measuring the voltage drop, which allows the resistance to be calculated. It’s important to follow proper safety procedures when measuring battery resistance to avoid short circuits or damage to the battery.

Why is it important to calculate battery voltage?

Calculating battery voltage is crucial for several reasons. It helps in assessing the health and state of charge of a battery, determining if a battery can effectively power a device, and in designing battery-powered systems to ensure compatibility and efficiency. Understanding battery voltage also aids in troubleshooting and maintaining battery-powered systems, ensuring they operate safely and effectively.