What term describes the voltage measurement of a battery when it is not connected to a circuit?

• A. Open Circuit Voltage
• B. Under Load Voltage
• C. Terminal Voltage
• D. Charge Voltage

Answer: (A)

Open-circuit voltage is the voltage you measure across a battery’s terminals when nothing is drawing current from it. Since no current flows, there’s no voltage drop inside the cell due to its internal resistance, so the reading equals the battery’s electromotive force (EMF). This is why you read this value with a high-impedance voltmeter right after disconnecting the battery.

When a load is connected and current flows, the terminal voltage can drop because of the internal resistance—this is the under-load (or loaded) voltage. The term terminal voltage generally refers to the voltage across the terminals while the device is operating, which can be different from the open-circuit value. Charge voltage refers to the voltage seen during charging and isn’t the term for the no-load condition.