A method for charging a battery includes measuring the battery's voltage and comparing the battery voltage to a first threshold voltage. The method includes operating the battery in a charging mode if the measured battery voltage is less than the first threshold voltage, wherein operating in the charging mode comprises applying a charging signal to the battery. The charging signal has an oscillating triangular waveform superimposed on a DC bias signal. The method includes measuring the battery's current consumption and comparing the current consumption to a first threshold current. The method includes operating in a maintenance mode if the battery's current consumption is less than the first threshold current, wherein operating in the maintenance mode comprises terminating application of the charging signal to the battery. The method includes measuring, during operation in the maintenance mode, the battery's voltage and comparing the measured voltage to a second threshold voltage. The method includes applying the oscillating triangular waveform superimposed on the DC bias signal until the battery's voltage is equal to or greater than the second threshold voltage.