US Patent 10008870 Powered case for portable electronic device

A case for an electronic device includes a front member having an aperture for interacting with a touchscreen of the electronic device and a back member that includes a rechargeable power cell, a switched electrical interface, an electromechanical switch, and current monitoring circuitry. The switched electrical interface has an enabled mode in which electrical current is permitted to flow from the rechargeable power cell of the case to the installed electronic device and a disabled mode in which the electrical current is not permitted to flow to the installed electronic device. The electromechanical switch transitions the switched electrical interface from the disabled mode to the enabled mode. The current monitoring circuitry automatically toggles the switched electrical interface from the enabled mode to the disabled mode when the magnitude of the electrical current flowing from the case to the electronic device decreases to a predetermined value.