A circuit charges and maintains a battery. The circuit includes a microprocessor for receiving a current sense signal and a voltage sense signal. The microprocessor generates control signals for selectively operating the circuit in a charging mode and in a maintenance mode. The circuit includes a current sense circuit for measuring the battery's current consumption and generating the current sense signal responsive to the measured current consumption. The circuit includes a voltage sense circuit for measuring the battery's voltage and generating the voltage sense signal responsive to the measured battery voltage. The circuit includes a waveform generator circuit for receiving the control signals, and operating in response thereto to apply a charging signal to the battery when in the charging mode and to deactivate the charging signal when in the maintenance mode. The charging signal has an oscillating triangular waveform superimposed on a DC bias signal.