The invention discloses an electric vehicle. Air is supplied from a passenger cabin of a vehicle to an intake passage between the passenger cabin and a battery of the vehicle. The vehicle may be an electric vehicle such as a hybrid electric vehicle (HEV) or a battery-only electric vehicle (BEV). A signal indicating a blockage of air flow through the battery is generated in response to a differencein temperature exceeding a predetermined magnitude. The difference in temperature is between (i) the intake passage and (ii) the passenger cabin.