Tesla’s early push for manufacturing the Model S prioritized release dates over quality control. Some of their earliest Model S electric sedans were shipped with a flawed battery pack which was prone to coolant leaks, which inevitably would lead to possible fires. Apparently, the company was cutting corners in this part of the Model S in order to ensure shipment in mid-2012, right when they started establishing themselves as a large scale manufacturer.
According to Business Insider, there were two problems that were often seen in the Model S battery packs. First, a third-party testing firm told Tesla that the aluminum they used was susceptible to cracks and pinholes. Lastly, their coil was ‘loosely’ hanging, which could turn into more coolant leaks.
All in all, Tesla still maintains record for safest cars in the world.