Compare lead-acid and nickel-cadmium aircraft batteries regarding energy density, temperature performance, and charging behavior.

Compare lead-acid and nickel-cadmium aircraft batteries regarding energy density, temperature performance, and charging behavior.

• A. Nickel-cadmium has higher energy density, good low-temperature performance, and rapid high-current capability; lead-acid is rugged and inexpensive but heavier.
• B. Lead-acid has higher energy density and better low-temperature performance than NiCd.
• C. Lead-acid and NiCd have identical characteristics.
• D. NiCd is cheaper and has poorer high-current capability.

Answer: (A)

The question tests how the two battery chemistries compare in energy storage, behavior in cold conditions, and how they charge. Nickel-cadmium cells provide more energy per unit weight than lead-acid, so for the same amount of stored energy, a NiCd pack is lighter. That higher energy density is crucial in aviation where weight matters. In cold temperatures, NiCd performs well and can deliver reliable current, which is essential for engine starting and avionics in winter conditions. Lead-acid, by contrast, loses capacity and can have higher internal resistance as temperature drops, making starts harder and reducing usable energy. Charging behavior also differs. Nickel-cadmium batteries tolerate higher charging currents and rapid charging with appropriate controls, and they’re less prone to the sulfation problems that plague lead-acid packs. Lead-acid batteries require more careful, slower charging and are more susceptible to issues like gas formation and sulfation if not charged properly, especially after deep discharge or at low temperatures. So the statement that NiCd has higher energy density, good low-temperature performance, and rapid high-current capability, while lead-acid is rugged and inexpensive but heavier, best captures the practical trade-offs: NiCd offers better energy density and strong cold-weather/high-current performance, whereas lead-acid is cheaper and mechanically rugged but heavier and less capable in high-current delivery and cold-start conditions.

The question tests how the two battery chemistries compare in energy storage, behavior in cold conditions, and how they charge. Nickel-cadmium cells provide more energy per unit weight than lead-acid, so for the same amount of stored energy, a NiCd pack is lighter. That higher energy density is crucial in aviation where weight matters.

In cold temperatures, NiCd performs well and can deliver reliable current, which is essential for engine starting and avionics in winter conditions. Lead-acid, by contrast, loses capacity and can have higher internal resistance as temperature drops, making starts harder and reducing usable energy.

Charging behavior also differs. Nickel-cadmium batteries tolerate higher charging currents and rapid charging with appropriate controls, and they’re less prone to the sulfation problems that plague lead-acid packs. Lead-acid batteries require more careful, slower charging and are more susceptible to issues like gas formation and sulfation if not charged properly, especially after deep discharge or at low temperatures.

So the statement that NiCd has higher energy density, good low-temperature performance, and rapid high-current capability, while lead-acid is rugged and inexpensive but heavier, best captures the practical trade-offs: NiCd offers better energy density and strong cold-weather/high-current performance, whereas lead-acid is cheaper and mechanically rugged but heavier and less capable in high-current delivery and cold-start conditions.