Patent ID: 7498774

Claim:
A battery pack for an associated hand-held electric machine tool ( 1 ) and for an associated charging device ( 13 ), the battery pack comprising: a plurality of battery cells ( 11 ), an analog temperature sensor ( 3 ) with a negative temperature coefficient, and a temperature measuring interface ( 4 ), which is accessible from the outside of the battery pack for controlling an operation of battery protection electronics ( 5 ) arranged in the hand-held electric machine tool ( 1 ) and in the charging device ( 13 ), the battery protection electronics ( 5 ) having: a battery protection logic ( 6 ), and a power switch ( 8 ) arranged in the circuit path ( 7 ) of the battery pack, wherein the battery pack is provided with an emergency protection circuit ( 10 ) connected to each of the plurality of battery cells and connected in parallel with the analog temperature sensor ( 3 ) and which, in emergency situations, actively reduces to a zero value a total resistance (R) that is measurable from the outside via the temperature measuring interface ( 4 ), wherein the total resistance (R) which is actively reduced to the zero value simulates an infinitely high temperature that is registered by the battery protection electronics ( 5 ), and in response, the battery protection electronics ( 5 ) opens the power switch ( 8 ), thereby causing a safe interruption of the circuit path ( 7 ).