The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 26, 1978
Filed:
Aug. 19, 1976
David H Bennefeld, Anoka, MN (US);
Introl Corp., Minneapolis, MN (US);
Abstract
An improved battery charger having a current limiting transformer for supplying a charging current. The transformer includes primary and secondary coils wound about a core and has a shunt path for a portion of the magnetic flux induced by the voltage appearing on the primary. A pair of silicon controlled rectifiers are alternately triggered into their forward conductive states at points relatively early in each alternating current half cycle to provide a maximum charging current when a substantially discharged battery is to be recharged. As the charging process progresses, the battery voltage increases and at a predetermined value of the battery voltage a smooth transition from the current-controlled mode to a voltage-controlled mode is inaugurated. After the change to the voltage-controlled mode has been completed, the SCRs are triggered into conduction much later in each cycle, thereby furnishing a very low or trickle current which can be continued indefinitely without damage to the battery. Simple adjustments are provided for determining the maximum current charging rate and the particular voltage at which the changeover is to begin. Provision is also made for preventing an initial sudden current surge when first turning on the power, thereby avoiding any unnecessary blowing of fuses.