Mitsubishi Motors Corp. said Wednesday it will continue the production and shipment halt of its Outlander plug-in hybrid electric vehicle because it has yet to pinpoint the cause of the apparent short-circuiting of at least one of the model’s lithium-ion batteries.

In March an employee at an MMC dealership in Kanagawa Prefecture noticed an unusual smell and found the battery’s housing had melted after the vehicle’s lithium-ion battery was recharged. Two other battery-related incidents have since been reported.

An investigation conducted by Mitsubishi Motors and its parts suppliers — including GS Yuasa Corp., which made the vehicle’s lithium-ion battery — indicate that improper handling of the battery by an assembly line worker might have caused a deformity, the automaker said.

But what led the battery to short-circuit and melt still remains unknown and there might be additional causes, a Mitsubishi Motors official said.

The automaker added it is aiming to pinpoint the cause by the end of April and said it will judge whether to order a recall of the model after finishing the investigation.

GS Yuasa also makes the lithium-ion batteries for Boeing’s 787 Dreamliner new-generation jetliners, which have been grounded worldwide due to apparent battery-related problems.