In the 2016 hoverboard recalls, what component most often caused overheating fires?

Lithium-ion batteries most often caused overheating fires in the 2016 hoverboard recalls.

Hoverboards became a major consumer-safety issue in late 2015 and 2016 after reports that some devices overheated, caught fire, or exploded while charging. Investigations focused on lithium-ion battery packs, chargers, and battery-management systems. Poor manufacturing controls, damaged cells, and incompatible or defective chargers could allow thermal runaway, a rapid self-heating reaction.

The U.S. Consumer Product Safety Commission recalled or warned about numerous hoverboard models. Major retailers and airlines restricted the devices, and certification requirements became more prominent. In the United States, the agency said hoverboards should meet applicable safety standards before being sold.

The term “hoverboard” is itself a common source of confusion: these products did not actually hover. They were two-wheeled, self-balancing electric boards. The recall problem concerned their rechargeable lithium-ion power systems, not a separate hover technology.