Zero Motorcycles is recalling certain 2013 models of the street-legal FX and XU because of a defect in the waterproofing of their batteries.

According to documents released by the National Highway Traffic Safety Administration, defects in the internal sealing in the battery could allow water to leak inside and contact the power cells. This may cause the cells to erode and release their electrolyte. The released electrolyte could then form a conductive path between cells, resulting in a rapid temperature increase and the release of gasses.

The problem first arose on April 3 with a report of a leak from a module on a 2013 Zero FX. The motorcycle was returned to Zero who handed it over to battery supplier Farasis for analysis. Over the next few weeks, Zero received additional reports and noticed similar issues on some units still in the company’s inventory. Analysis on these affected units led to the conclusion of a a defect in the sealant.

Zero completed its investigation on June 19, concluding the issue affected 2013 FX and XU models produced before May 21, 2013. The recall documents also

Dealers will replace the battery modules on affected units at no charge. The recall campaign affects 128 units.

[Source: NHTSA]