A condition that can occur in a nickel-cadmium battery in which the battery overheats because of excess current. A nickel-cadmium battery has a very low internal resistance, but if an excessive amount of current flows from it, even its low resistance will cause it to overheat. The center cells get hotter than the outer cells, which transfer some of their heat to the outside air, and when the center cells overheat, their voltage and resistance both drop.

When the generator puts current back into the battery, the center cells take the most current and get even hotter. As they get hotter, their voltage and resistance continue to drop, and they take more current. This current increase continues until the battery is destroyed.