Which statement is generally true regarding the charging of several aircraft batteries together?

Which statement is generally true regarding the charging of several aircraft batteries together?

• A. Batteries of different voltages (but similar capacities) can be connected in parallel with each other across the charger and charged using the constant voltage method.
• B. Batteries of different voltages (but similar capacities) can be connected in series with each other across the charger and charged using the constant current method.
• C. Batteries of the same voltage and same ampere-hour capacity must be connected in series with each other across the charger and charged using constant current method.
• D. Batteries of different voltages must be connected in parallel across the charger regardless of capacity.

Answer: (B)

The big idea is to control the charging current so every battery in the group receives the same amount of charge. If batteries with different voltages were connected in parallel, the higher-voltage units would push current into the lower-voltage ones, creating unsafe circulating currents and uneven charging. Wiring them in series makes the same charging current pass through every battery, so they share the charge as a group even if their starting voltages differ. A constant-current charger can then drive the series string, and the total voltage required will be the sum of the individual voltages, rising as each battery reaches full charge. This approach avoids the hazards of parallel charging batteries at different voltages and aligns with the practical need to charge similar-capacity batteries together without forcing strict identical voltages.

The big idea is to control the charging current so every battery in the group receives the same amount of charge. If batteries with different voltages were connected in parallel, the higher-voltage units would push current into the lower-voltage ones, creating unsafe circulating currents and uneven charging. Wiring them in series makes the same charging current pass through every battery, so they share the charge as a group even if their starting voltages differ. A constant-current charger can then drive the series string, and the total voltage required will be the sum of the individual voltages, rising as each battery reaches full charge. This approach avoids the hazards of parallel charging batteries at different voltages and aligns with the practical need to charge similar-capacity batteries together without forcing strict identical voltages.