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:
Aug. 27, 1991
Filed:
Feb. 26, 1988
Pradeep M Bhagwat, Baltimore, MD (US);
Alan A Gilmore, Baltimore, MD (US);
Fred S Watts, Shrewsbury, PA (US);
Black & Decker Inc., Newark, DE (US);
Abstract
An isolated battery charger suitable for charging lead-acid batteries includes a high-frequency power conditioner that rectifies source current to a DC value and chops the current at a comparatively high frequency, e.g., 25 KHz, using a pair of MOSFET switches (138 and 140) to provide power pulses to the primary of a step-down transformer (T.sub.1). The output of the step-down transformer (T.sub.1) is presented to an enhancement mode MOSFET (206) in series circuit with the battery (B) to be charged with the gate bias of the MOSFET controlled in response to the sensed voltage of the battery to provide current to the battery as a function of its charge. Control circuitry is provided to limit charging to a small `trickle` level in the event the battery (B) is fully discharged to increase its charge level prior to initiating the full charge current. The provision of a voltage converter (100) operating at a relatively high frequency allows use of a lightweight and compact transformer (T.sub.1) that nonetheless provides a high current for charging.