Patent ID: 8237412

Claim:
A battery charger comprising: a battery charging circuit for providing a battery charging current for charging a battery, wherein said battery charging current circuit repeatedly measures the voltage of said battery while said battery is being charged by an AC input source which defines AC zero crossings and provides first charging cycles during charging while the battery voltage is less than V MAX plus 0.2 volts and second charging cycles after the battery voltage reaches V MAX plus 0.2 volts, wherein said first charging cycle comprises two DC charging current values each having a non-zero average values defining a maximum level charging current and a minimum level charging current, said maximum level charging current and a minimum level charging current alternated back and forth until said battery voltage reaches V MAX plus 0.2 volts, said maximum level charging current and a minimum level charging current selected to cause said battery to be at least partially charged during said first charging cycle at a voltage greater than V MAX , wherein V MAX is the maximum recommended charging voltage by the battery manufacturer, and said second charging cycle is initiated when the battery voltage is greater than V MAX plus 0.2 volts and continues charging at a constant voltage.