Means and methods for battery charge retention circuits

Claim 1

A battery charge retention device comprising: a transformer having a primary winding and first and second secondary windings, the first secondary winding including a centertap; first and second diodes having their cathodes connected to each other and having their anodes respectively connected across the opposing legs of the first secondary winding; a manually preselectable timer including a high impedance motor winding and a set of normally open contacts which are held in closed position during timer operation; positive and negative output terminals, the positive output terminal being connected to the common cathode connection of the two diodes and the positive terminal of a battery, and the negative output terminal being connected to the negative terminal of the battery and to one leg of the second secondary winding; the motor winding being connected in series with the other leg of the second secondary winding and the anode of the first diode; and the timer contacts being connected in series with the centertap of the first secondary winding and the negative output terminal; whereby when the timer is set charging current will flow from the first secondary winding through the diodes to the battery and back through the timer contacts to the centertap, and when the timer is not set charge retention current will flow from the second secondary winding through the high impedance motor winding, the first diode, the battery and back to the second secondary winding.