The present disclosure includes a method of charging a battery. In one embodiment, the method comprises receiving, in a battery charging circuit on an electronic device, an input voltage having a first voltage value from an external power source. The battery charger is configured to produce a charge current having a first current value into the battery. The input current limit and/or duty cycle of the charger is monitored. Control signals may be generated to increase the first voltage value of the input voltage if either (i) the input current limit is activated or (ii) the duty cycle reaches a maximum duty cycle. The charger also receives signals indicating a temperature inside the electronic device and generates control signals to decrease the value of the input voltage when the temperature increases above a threshold temperature.