A following car skidded and the driver was seriously injured when she collided with an oncoming lorry. Scanning electron microscopy or SEM showed that the nylon connector had fractured by stress corrosion cracking (SCC) due to a small leak of battery acid. Nylon is susceptible to hydrolysis when in contact with sulfuric acid, and only a small leak of acid would have sufficed to start a brittle crack in the injection moulded nylon 6,6 connector by SCC.