Which statement about preventing thermal runaway is most accurate?

• A. Carefully monitor middle-cell temperature and control charging current
• B. Use a high-rate charge only
• C. Rely on voltage only
• D. Discharge completely before charging

Answer: (A)

Preventing thermal runaway hinges on detecting heat buildup and keeping charging energy within safe limits. Thermal runaway starts when a cell overheats, which speeds up internal chemical reactions and generates more heat in a self-reinforcing loop. The way to stop that loop is to monitor temperature directly and keep the charging current at a level the cooling system can handle. In a multi-cell pack, the middle cell is often the hottest point because heat has to travel from the center toward the edges, so monitoring its temperature gives the best early warning of rising heat. If the middle-cell temperature climbs, the charging current should be reduced or halted to prevent further heating. Relying on voltage alone isn’t reliable, since a cell can show normal voltage even as it overheats. Requiring a complete discharge before charging isn’t a guaranteed safeguard and isn’t necessary with proper temperature-aware control.