Open-circuit voltage (abbreviated as OCV or V_OC) is the difference of electrical potential between two terminals of an electronic device when disconnected from any

circuit Circuit may refer to: Science and technology Electrical engineering * Electrical circuit, a complete electrical network with a closed-loop giving a return path for current ** Analog circuit, uses continuous signal levels ** Balanced circu ...

. There is no external load connected. No external

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movin ...

flows between the terminals. Alternatively, the open-circuit voltage may be thought of as the voltage that must be applied to a

solar cell A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.battery to stop the current. It is sometimes given the symbol V_oc. In network analysis this

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge t ...

is also known as the Thévenin voltage. The open-circuit voltages of batteries and solar cells are often quoted under particular conditions (state-of-charge, illumination, temperature, etc.). The potential difference mentioned for batteries and cells is usually the open-circuit voltage. The value of the open-circuit voltage of a

transducer A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and cont ...

equals its

electromotive force In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal or ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical '' tr ...

(emf), which is the maximum potential difference it can produce when not providing current.

Example

Consider the circuit: Given Circuit

If we want to find the open-circuit voltage across the 5Ω

resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias activ ...

, first disconnect it from the circuit: Modified Circuit

Find the equivalent resistance in loop 1 to find the current in loop 1. Use

Ohm’s law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equati ...

with that current to find the

potential drop Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts, and across connectors are undesirab ...

across the resistance C. Note that since no current is flowing through resistor B, there is no potential drop across it, so it does not affect the open-circuit voltage. The open-circuit voltage is the potential drop across the resistance C, which is:

\frac\ 100\ V_\sim\ .

This is just an example. Many other ways can be used.

References

Electrical parameters {{Energy-stub

Example

See also

References