What is a result of cell imbalance in a nickel-cadmium battery?

• A. It reduces overall voltage
• B. Low internal resistance allows current to flow between unbalanced cells generate heat
• C. It increases charging efficiency
• D. It prevents overheating

Answer: (B)

When cells in a nickel-cadmium pack aren’t at the same state of charge, the higher-charge cells can drive current into the lower-charge ones. That intercell current flows through the cells’ internal resistance and interconnections, and the energy lost as I squared R dissipates as heat inside the pack. Because NiCd cells have relatively low internal resistance, even modest intercell currents can generate noticeable heat, which is why imbalance leads to heating and can shorten cell life or cause safety concerns. This heating is the direct consequence of energy moving between cells rather than built-up voltage or efficiency improvements, and it doesn’t mean the overall pack voltage is inherently reduced or that overheating is prevented.