Hyundai Motor is set to replace the batteries in some 82,000 electric vehicles over risks they could catch fire.

Combined with an earlier recall, the problem looks set to cost the automaker about $900 million.

The latest move mainly applies to its best-selling EV, the Kona.

It was first recalled in October for a software upgrade after a series of fires.

But in January one of the upgraded cars then caught fire, prompting South Korean authorities to probe whether the first recall was adequate.

The unit of LG Chem which makes the batteries said Hyundai had misapplied its suggestions regarding battery management.

It said the batteries themselves were not the fire risk.

There have been 15 cases of fires involving the Kona EV.

Most were in South Korea, but there were two in Canada and one each in Finland and Austria.

Hyundai Motor shares were down close to 4 percent in afternoon trade on Wednesday (February 24).