1. A portable electronic device comprising: a rechargeable power source; and a battery warning system that executes logic to generate a low battery charge warning, the logic including code to: obtain data related to a charge state of the rechargeable power source at a time t n ; determine a predicted usage of the device for a period of time relative to time t n ; determine a predicted power requirement to power the device during the predicted usage; determine if the charge state of the power source is sufficient to supply the power, down to a threshold level, for the predicted power requirement; and generate a notice if the charge state is not sufficient for the predicted power requirement.