Abstract: A switch mode battery charging system wherein a switch mode power supply is provided which is operating at a frequency substantially above a line frequency of AC line voltage supplying the battery charging system. The system of the invention can automatically switch back and forth between an equalize mode and a float mode of operation. The system of the invention also compensates for severe line voltage variations, provides a low ripple controllable DC voltage and current output, and is compact, light weight, and highly efficient in view of its high frequency operation. Furthermore, the system of the invention provides optimized and automatic charging of batteries in various states of discharge. The system automatically senses to determine whether or not battery equalization and desulfation is necessary, and automatically determines a length of time for equalization depending upon a charge state of the battery.

Abstract: A full wave DC to AC inverter having two SCR inverter switches which alternately conduct to connect a DC source across one section or the other of a center tapped power transformer primary to establish an alternating current in the secondary. A commutating circuit includes a single capacitor which is charged during the conduction of the inverter switches and is alternately connected to the conducting inverter switch to turn it off. The commutating circuit employs a single transformer which has a primary winding connected in series with the primary winding of the power transformer and a secondary winding connected through an SCR and to the capacitor. A pair of SCR's, which are gated on by commutation trigger circuits, control the discharge of the capacitor to the appropriate SCR inverter switch.