Boeing 787 batteries may have been overcharged - The Daily Yomiuri

The Yomiuri Shimbun

The main batteries of a Boeing 787 passenger jet that made an emergency landing at Takamatsu Airport on Wednesday may have become overheated while recharging, resulting in their carbonization, according to the Japan Transport Safety Board and other sources.

The board believes the overcharge may have allowed the batteries to conduct an unusually strong current or high voltage, later resulting in problems.

The main batteries are eight lithium-ion batteries housed in a metal container 34 centimeters in length, 28 centimeters in width and 22 centimeters in depth.

When the board opened and examined the container on Thursday, the contents were reportedly black and charred, and the container weighed 4.7 kilograms less than the original weight of 28.3 kilograms.

The board believes the electrolytic solution inside the batteries heated up, damaging the batteries and causing the solution to leak.

Normally used when an airplane starts its engines, the batteries are charged by electrical supply systems in the fuselage during the flight.