Deflection sensitive coolant activated drain plug detection system for high voltage battery packs

A battery pack with a drain plug and a circuit to detect when a liquid coolant has entered the battery pack. A soluble plug may be disposed within the cavity of the carrier; the soluble plug is configured to at least partially dissolve when fluidly coupled with a coolant allowing a portion of the coolant to flow between the inlet and the outlet and out of the battery pack. A strain gauge cooperative with the carrier such that a measured resistance change in the strain gauge corresponds to the soluble plug in contact with the liquid coolant. An associated circuit with the drain plug provides notification of the activation of the drain plug to the on-board computer systems.