Tesla’s earliest Model S electric sedans shipped with a flawed battery pack design that was prone to coolant leaks which could lead to fires, according to Business Insider. The report describes how the company appears to have cut corners on this particular part of the Model S, which Tesla was scrambling to ship in mid-2012 as it started to establish itself as a mass-market electric automaker.
The new report comes as Tesla was ranked last in JD Power’s annual study of new vehicle quality, and shortly after the National Highway Traffic Safety Administration (NHTSA) announced an investigation into early Model S touchscreen failures.
There were two specific problems with the Model S battery packs, according to Business Insider, which spoke to three former employees and viewed internal emails and documents. First, a third-party testing firm told Tesla that the aluminum the company was using at the end of the battery pack’s cooling coil was susceptible to cracks and pinholes, which could lead to coolant leaks. Beyond that, the fitting at the end of this coil was imperfect, with one employee describing them as “hanging by a thread.” This also made the packs susceptible to leaks.
Tesla “continued to find leaking coils in various stages of production through the end of 2012,” according to the outlet. The problem was flagged to senior management, but the cars were ultimately sold.
Tesla has maintained that its cars are the safest in the world and self-reports annual vehicle fire statistics that are far lower than those found in gasoline-powered cars. The company has made multiple changes to the Model S over the years to reduce the risk of fires, though. It shipped a software update in 2013 that made the Model S ride higher at highway speeds to lower the chance of debris puncturing the battery pack and added more physical protection to new packs coming off the line, all after an NHTSA investigation into multiple fires. (The agency closed the investigation in 2014.) Tesla also released a software update in 2016 to “provide extra security during charging” after a Model S caught fire in Norway.