Patent ID: 8717186

Claim:
An apparatus comprising: at least one contact sensor comprising a structure of two or less layers of electrically insulating material, said structure configured to have a first face in contact with a battery and a second face opposite the first face, the second face being coated with a layer of electrically conductive material, said structure having two layers of electrically insulating material further configured to have a layer of electrically conductive material interposing therebetween, the material of a first electrically insulating layer in contact with a case of said battery on the first face being quantum tunneling composite (“QTC”), and a second layer of electrically insulating material comprising the second face; and a capacitance measuring module connectable to said at least one contact sensor configured to determine an increase in capacitance of said layer of coated electrically conductive material from a reference value and output a warning signal if the increase of said capacitance exceeds a pre-determined threshold.