Ford F-150 Lightning recall reveals cause of battery fire [Video]

The National Highway Traffic Safety Administration (NHTSA) has revealed the root cause of the battery fires that halted Ford (F) F-150 Lightning production.

Back in early February a battery defect resulted in a fire in an F-150 Lightning that was awaiting final inspection, and the fire spread to two other vehicles. Ford halted production then as battery supplier SK On figured out a solution, with production restarting on March 13th.

Now recall documents released by NHTSA detail exactly what happened in those vehicles, leading to the recall of 18 Ford F-150 Lightnings.

In one of NHTSA’s safety recall reports related to the F-150 battery issue, the report stated a manufacturing defect in the battery cells “may result in an internal short circuit when the high voltage battery is at a high state of charge… which could result in a fire.”

The report went on to detail that the defect was due to “production process deviations at the supplier [where] the cathode aluminum tabs may contact the anode electrode material causing an internal short circuit” when the battery is at a “high state of charge.”

Ford F-150 Lightning battery and powertrain diagram

Ford F-150 Lightning battery and powertrain diagram

The report stated that Ford was able to replicate the issue, and could trace the defective battery packs down to the exact vehicles that had them installed, leading to the recall of those 18 F-150 Lightnings. Remediation of the issue will require the installation of new battery packs installed free of charge.

Ford also reported that no F-150 Lightnings in the field suffered from any battery short circuits leading to fires.

“In the weeks ahead, we will continue to apply our learnings and work with SK On’s team to ensure we continue delivering high-quality battery packs – down to the battery cells,” a Ford spokesperson told Yahoo Finance in a statement when the automaker announced it would be restarting production.

While it’s a positive that Ford was able to diagnose and fix the battery issue, the big question for investors and analysts is whether Ford’s production and reliability issues are going to plague its F-150 Lightning rollout, which is still in its nascent stage and figures to be a huge growth driver for its EV unit in the years to come.

Pras Subramanian is a reporter for Yahoo Finance. You can follow him on Twitter and on Instagram.

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Originally published