State-of-charge-measurable batteries

摘要

A storage device allows the state of charge of a main battery to be determined by measuring the state of charge of a dummy battery. The storage device may provide power to an electronic appliance such as a portable computer. The main and dummy batteries each have a storage capacity and a self-discharge rate. The storage capacity of the dummy battery is less than the storage capacity of the main battery; for example, the storage capacity of the dummy battery may be only about 1% of that of the main battery. The main and dummy batteries are configured so that the self-discharge rates thereof are substantially equal. The storage device also includes discharge circuitry which is configured so that the dummy battery discharges at a rate faster than the main battery when a load is connected to and drawing current from the main battery.