What is the open-circuit voltage of a lead-acid cell?

What is the open-circuit voltage of a lead-acid cell?

• A. 2.0 volts
• B. 2.1 volts
• C. 2.2 volts
• D. 1.8 volts

Answer: (B)

Open-circuit voltage is the voltage a lead-acid cell produces when no current is flowing; it reflects the cell’s electromotive force at rest. For a healthy, fully charged lead-acid cell, this resting voltage is about 2.1 volts. That’s why 2.1 volts is the correct value. A rough nominal of around 2.0 V exists, but open-circuit voltage is typically a bit higher, near 2.1 V. A reading near 2.2 V would be unusual for a resting cell, and 1.8 V indicates a discharged condition. In a 12-volt battery, six cells in series give about 12.6 V when fully charged (6 × 2.1 V).

Open-circuit voltage is the voltage a lead-acid cell produces when no current is flowing; it reflects the cell’s electromotive force at rest. For a healthy, fully charged lead-acid cell, this resting voltage is about 2.1 volts. That’s why 2.1 volts is the correct value. A rough nominal of around 2.0 V exists, but open-circuit voltage is typically a bit higher, near 2.1 V. A reading near 2.2 V would be unusual for a resting cell, and 1.8 V indicates a discharged condition. In a 12-volt battery, six cells in series give about 12.6 V when fully charged (6 × 2.1 V).