FAA Aviation Mechanic General (AMG)Fundamentals of Electricity and ElectronicsMedium
A technician is checking the state of charge of a 24-volt nickel-cadmium aircraft battery. What is the approximate open-circuit voltage per cell for a fully charged nickel-cadmium cell?
- A2.2 volts
- B1.5 volts
- C2.0 volts
- D1.2 volts
Show answer & explanationAnswer & explanation
Correct answer: D. 1.2 volts
A fully charged nickel-cadmium (NiCad) cell typically has an open-circuit voltage of approximately 1.2 volts. This is a characteristic property of NiCad chemistry.
Why the other options are wrong
- A. 2.2V is a typical full-charge voltage for a lead-acid cell under light load, not NiCad.
- B. 1.5V is closer to a primary alkaline cell voltage.
- C. 2.0V is characteristic of a lead-acid cell, not NiCad.
Nickel-Cadmium Cell Voltage
The characteristic open-circuit voltage produced by a single nickel-cadmium electrochemical cell, which is approximately 1.2 volts when fully charged.
- Nominal voltage is 1.2V per cell.
- Stable voltage output during discharge.
- Susceptible to memory effect if not properly discharged.
Memory trick: Lead-Acid is heavy with 2V, NiCad is lighter with 1.2V.