A portable electronic device including a battery coupled to an accessory circuit, a battery monitoring circuit coupled to the battery, and a processor connected to the battery monitoring circuit and the accessory circuit. The battery monitoring circuit determines an output current of the battery, and the processor receives an indication of the output current. The processor determines, based on the indication of the output current of the battery, a power characteristic of the accessory circuit, and control a power that is to be provided to the accessory circuit based on the power characteristic of the accessory circuit.