Transformerless battery charger in combination with a battery, and method of charging a battery

Claim 1

In combination with a battery, a transformerless battery charger comprising circuit means for connecting said battery to an A.C. power source to supply charging current to the battery, said circuit means comprising: inductor means in series with said A.C. power source; electronic switch means in series with said A.C. power source, said electronic switch means being normally non-conductive, to thereby open the charging circuit for the battery; and electronic trigger means for turning on said electronic switch means to close the charging circuit for the battery as a function of the difference between the instantaneous voltage from said A.C. power source and the battery voltage; said electronic switch means and said electronic trigger means being jointly operable to provide a charging current to the battery during the A.C. power cycle long enough to produce a significant battery-charging effect but short enough to avoid harmful internal heating of the battery; said electronic switch means being a Triac having a control electrode connected to said electronic trigger means; said circuit means also including a full-wave rectifier bridge having a pair of opposite input terminals, one of which is connected to said Triac and the other to said A.C. power source, and a pair of opposite output terminals connected across the battery being charged.