State-of-charge-measurable batteries

An electronic appliance comprising:

• a storage device including:
• a main battery for providing power to said electronic appliance, said main battery having a storage capacity and a self-discharge rate;
• a dummy battery having a storage capacity, a self-discharge rate, and a state of charge, said storage capacity of said dummy battery being less than said storage capacity of said main battery, said self-discharge rate of said dummy battery being substantially equal to said self-discharge rate of said main battery;
• and
• discharge circuitry connected to said dummy battery and configured so that said dummy battery discharges at a rate faster than said main battery when a load is connected to said main battery;
• and
• signaling circuitry connected to said storage device for monitoring said state of charge of said dummy battery, said signal circuitry providing a signal when said state of charge of said dummy battery is less than a predetermined threshold;
• and
• a signal device connected to said signaling circuitry for receiving said signal.

A method for providing a state of charge of a storage device, said method comprising the steps of:

• discharging a main battery at a first discharge rate;
• discharging a dummy battery at a second discharge rate, said second discharge rate being greater that said first discharge rate;
• monitoring a state of charge of said dummy battery;
• and
• signaling when said state of charge of said dummy battery is below a predetermined level.