Exam Questions And Correct Answers

FAA Repairman Certificate – Aircraft Battery Maintenance & Repair Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the main purpose of a vent in a lead-acid aircraft battery?
• To prevent electrolyte evaporation
• To allow gas to escape during charging
• To control internal pressure
• To equalize cell voltage

Rationale: During charging, hydrogen and oxygen gases are

produced, and the vent allows these gases to escape, preventing pressure buildup.

2. Nickel-cadmium batteries differ from lead-acid batteries primarily in:

• Cell voltage
• Plate construction
• Electrolyte composition 1 / 4

• Charging voltage

Rationale: Nickel-cadmium batteries use a potassium hydroxide

electrolyte, unlike sulfuric acid in lead-acid batteries.

• What is the nominal cell voltage of a lead-acid battery?
• 2.1 volts
• 1.2 volts
• 3.6 volts
• 4.2 volts

Rationale: Each lead-acid cell provides approximately 2.1 volts when

fully charged.

4. The nominal cell voltage of a nickel-cadmium battery is:

• 2.0 volts
• 1.2 volts
• 2.5 volts
• 1.5 volts

Rationale: Ni-Cd batteries produce about 1.2 volts per cell under

normal operating conditions.

5. The electrolyte level in a lead-acid battery should be checked:

• Only when discharged
• After charging
• During charging
• Before charging 2 / 4

Rationale: The electrolyte expands during charging; thus, levels

should be checked after charging for accuracy.

• What is the recommended charging method for Ni-Cd batteries?
• Constant current
• Constant voltage with temperature monitoring
• Pulse charging
• Float charging

Rationale: Ni-Cd batteries are charged using constant voltage while

monitoring temperature to prevent overheating.

7. Sulfation in a lead-acid battery is caused by:

• Prolonged discharge or undercharging
• Overcharging
• Excessive water addition
• High temperature

Rationale: Sulfation forms when a battery is left discharged, causing

lead sulfate crystals to harden on the plates.

8. When charging a lead-acid battery, the correct polarity connection is:

• Positive to positive, negative to negative
• Positive to negative, negative to positive
• Either way
• It depends on the charger type

Rationale: Reversed polarity causes serious damage; terminals must

be matched correctly. 3 / 4

• A Ni-Cd battery showing low capacity after several cycles may be

suffering from:

• Sulfation
• Memory effect
• Corrosion
• Electrolyte loss

Rationale: Repeated shallow discharges can cause a Ni-Cd battery to

"remember" a lower capacity, known as memory effect.

• When performing maintenance on a lead-acid battery, the

technician should always wear:

• Cotton gloves
• Acid-resistant gloves and goggles
• Wool gloves
• Latex gloves

Rationale: Protective gear prevents injury from sulfuric acid spills and

splashes.

• What is the correct specific gravity of a fully charged lead-acid

battery at 80°F?

A. 1.285 ± 0.015

B. 1.200 ± 0.020

C. 1.340 ± 0.010

• 1.100 ± 0.025
• / 4