US auto giant Ford recently reiterated SK On’s battery defect in recalling 18 F-150 Lightnings that led to the production shutdown of the electric pickup trucks after a battery fire incident last month.

“Ford is recalling 18 F-150 Lightnings due to a battery cell manufacturing defect, which occurred over a four-week period starting at the end of last year,” the carmaker said in a statement Friday local time. SK On is the battery supplier for the flagship model.

The trucks might have a similar battery issue like the one that caught on fire during a standard quality check on Feb. 4, but they were sent out to dealers and customers before the stop-shipment notice, sources said.

But rather than admitting its shipping error, Ford once again brought the matter to its battery maker and said, “The root cause identified (of the fire incident) was related to battery cell production at the SK On plant in Georgia.”

SK On has maintained its earlier stance on the fire issue.

“The pickup trucks under recall do not have problems rooted in battery technology,” said an SK On official.

Ford at that time claimed that there was a possible battery issue, without making further elaborations on whether the battery cell itself had a technological defect or whether it was a manufacturing problem that was discovered when installing the batteries in the trucks.

“According to Ford, there will be no additional recall (of the electric pickup trucks),” the official said, adding that it has not discussed with the carmaker yet whether SK On should cover the expense for replacing the defected batteries.

Experts say even if SK On is not at fault, Ford might push the battery maker to cover the expenses or hold them responsible on the recall.

“Although Ford might be responsible for carrying out a faulty manufacturing process, it is hard to prove the exact case of defect in electric cars,” said Kim Pil-su, a car engineering professor at Daelim University.

“Also, Ford has the upper hand as a customer company over SK On,” added Kim, saying that LG Energy Solution had to share the blame over GM’s recall on around 143,000 Chevrolet EV Volts and paid around 1.4 trillion won ($1.1 billion).

Kim said Ford might be piling on the pressure on the Korean firm to admit its responsibility in producing faulty electric vehicles, at a time when Ford's US launch of the first mainstream electric pickup truck has stuttered.

Ford initially opened customer reservations for the F-150 Lightning pickup trucks when it was unveiled in 2021. More than 200,000 reservations were made, however, Ford only managed to sell 15,000 units to customers last year. It posted $2 billion in losses in the cited period.