Abstract: A battery charging system has an effective pure DC power source charging at least one secondary charge acceptor utilizing an aqueous electrolyte. The applied effective voltage is equal to or slightly greater than the full charge level of said acceptor cell. An impedance/resistance is coupled between the power source and the secondary charge acceptor cell. The impedance/resistance is a value which reduces any AC component out of the secondary cell to no more than 5% of the total voltage out in order to reduce the counterelectromotive force responsive to the applied voltage. The impedance/resistance has a value which is selected to set the capacitive reactance of the acceptor cell and the inductance reactance of the power source at levels which reduce the counterelectromotive force of the acceptor cell throughout the full charge cycle in order to produce a cooling effect.

Abstract: A battery charger for a nickel-cadmium cell, or the like, uses a large battery, such as an acid-lead automobile battery. Electrodes depend from the fill caps and into the electrolyte to make a plurality of potential points. Each of the cells in the large battery includes two sets of plates, with the individual plates in each set being joined at one end by a common bus bar. A terminal extends from each of these bus bars through the case of the acid-lead battery, to provide another plurality of potential points. A small battery, such as at least one nickel-cadmium cell is coupled to selected ones of the potential points so that the potential across the selected potential points equalizes with the potential of the small battery.