Abstract: A converter for a rechargeable battery (e.g., lithium battery) is disclosed. In some embodiments, the converter includes a direct current (DC) to DC converter and a microcontroller unit (MCU). The DC to DC converter includes a switching circuit configured to generate a pulse width modulated (PWM) voltage from the rechargeable battery voltage, wherein the switching circuit is configured to set a variable duty cycle of the PWM voltage. The DC to DC converter also includes a filtering circuit configured to convert the PWM voltage into a DC output voltage having an output voltage level that is set in accordance with the variable duty cycle of the PWM voltage. The MCU is configured to adjust the variable duty cycle of the switching circuit such that the output voltage level of the DC output voltage emulates a discharge voltage curve of a dry battery while the rechargeable battery is being discharged.