Patent ID: 7349829

Claim:
A data logger for sensing and storing data when a primary power source has failed, comprising (a) a sensor providing a sensor output signal, (b) a sampler connected to the sensor to sample the output signal from the sensor at one or more designated time intervals during the primary power source failure state, and (c) a storage medium connected to the sampler to receive and store data representative of the sampled sensor output, the data logger further comprising, (d) at least one back-up power source, (e) a detector-switch connected to a primary power source and to one or more back-up power sources, the detector-switch detecting a condition indicative of the primary power source failure state, and connecting at least one back-up power source to provide power to the sampler, the storage medium and the sensor upon detection of the condition indicative of the primary power source failure state, and to activate the sampler to sample the sensor output signal, and to store data representative of the sampled sensor output.