The whole wrench thing has happened to me. It was on the bigger 12 volts marine/industrial batteries connected in parallel series for 24 volts to start a Detro

The whole wrench thing has happened to me. It was on the bigger 12 volts marine/industrial batteries connected in parallel series for 24 volts to start a Detroit Diesel 71 series engine. There was a nice arce and the end of the wrench melted.