A battery pack (2) for an associated hand-held electric machine tool (1) and for an associated charging device (13) including an analog temperature sensor (3) with a negative temperature coefficient and a temperature measuring interface (4) accessible from the outside. Battery protection electronics (5) arranged in the hand-held electric machine tool (1) and in the charging device (13), which have a battery protection logic (6) and a power switch (8) that is arranged in the circuit path (7) of the battery pack (2) can be influenced. The battery pack (2) is provided with an emergency protection circuit (10), which is connected in parallel with the analog temperature sensor (3) and which, in emergency situations, can actively reduce the total resistance (R) measurable from the outside via the temperature measuring interface (4).