A rechargeable battery with an internal microcontroller, a memory and a temperature sensor. The microcontroller draws a current from the cells internal to the battery used to power device to which the battery is attached. Normally, the microcontroller, is in a first operating mode in which the microcontroller draws a relatively low current. During these periods the temperature sensor generates a signal representative of the temperature of the battery. When the signal from the temperature sensor indicates the battery temperature exceeds a threshold temperature, the microcontroller enters a second operating mode in which the microcontroller draws a relatively high current. While in the second operating mode the microcontroller records in the memory data regarding the fact that the battery temperature exceeded the reference temperature and the amount of time the battery was at a temperature above the reference temperature.