According to one exemplary embodiment, an auto-synchronous power gauge for measuring total charge consumed from a power source of an electronic device includes an analog to digital converter for sampling a signal corresponding to current drawn from the power source, and one or more accumulators. The analog to digital converter produces digital outputs which are received and summed by the one or more accumulators. The auto-synchronous power gauge further includes a power mode detector for generating a power mode signal using the signal corresponding to current drawn from the power source, where the power mode signal is used by a controller to enable and disable the one or more accumulators and the analog to digital converter. The total charge consumed can be determined by a processor coupled to the auto-synchronous power gauge. In one embodiment, a sync signal from the processor provides input to the controller.