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:
Feb. 01, 1994
Filed:
Apr. 13, 1992
Steven J Stadnick, Lakewood, CA (US);
Robert K Taenaka, Granada Hills, CA (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
A battery system comprises a plurality of sodium-sulfur storage cells connected in series to form a battery, with voltage measurement leads attached across each of the individual storage cells. A charge-limiting circuit controllably isolates an individual storage cell from a charging current applied across the battery when the measured voltage across that individual storage cell exceeds a preselected maximum storage cell voltage. Preferably, the charge-limiting circuit includes a bypass circuit connected through the voltage measurement leads and a circuit element that becomes conductive when the voltage across the individual storage cell exceeds the preselected maximum storage cell voltage. There are a plurality of charge-limiting circuits, one for each of the storage cells of the battery. In operation, a high charging current is imposed on the battery while measuring the voltage across each individual storage cell, until the voltage measured across at least one of the storage cells exceeds a preselected reduced-current voltage that is less than the preselected maximum storage cell voltage. The charging current is thereafter reduced to a low charging current while continuing to charge the battery. The low charging current is bypassed around each of the individual storage cells as that storage cell reaches the maximum voltage, until all of the storage cells reach the same state of charge.