Patent ID: 7656120

Claim:
A rechargeable battery pack capable of providing electric power to an electronic device having a first battery, the rechargeable battery pack comprising: a body; a second battery inside the body and supplemental to the first battery inside the electronic device; and a first circuit inside the body and configured to dynamically change a charge current supplied from an external power source to the second battery based on a power consumption level of the electronic device; wherein: the first circuit comprises: a current sense subcircuit; a power limiting switch having a first terminal electronically coupled to an output of the current sense subcircuit; and a first resistor with a first end electronically coupled to a second terminal of the power limiting switch; the charge current comprises a first magnitude and a second magnitude less than the first magnitude; the power consumption level of the electronic device comprises a first level and a second level greater than the first level; the power consumption level of the electronic device is measured via the current sense subcircuit of the first circuit; when the power consumption level is less than the first level, the first circuit turns on the power limiting switch, via the output of the current sense subcircuit, to allow a flow of the charge current through the first resistor and to transmit the first magnitude of the charge current to the second battery; and when the power consumption level is greater than the second level, the first circuit turns off the power limiting switch, via the output of the current sense subcircuit, to inhibit the flow of the charge current through the first resistor and to transmit only the second magnitude of the charge current to the second battery.