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:
Apr. 01, 1997
Filed:
Aug. 17, 1994
Steven D Keidl, Rochester, MN (US);
Jeffrey S Rotter, Rochester, MN (US);
Steven W Steele, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A battery charging aparatus and method are provided for charging a battery using current control with a switching power supply charging circuit coupled to the battery. During a first charging phase, a predetermined constant charging current is applied to the battery. The battery voltage is monitored and a second charging phase is started when the battery voltage reaches a predetermined threshold voltage. During a second charging phase, a sequence of stepwise decreasing-amplitude current pulses are applied to the battery. The envelope for the decreasing current pulses is exponential which is characteristic of the current for voltage controlled charging methods. The battery voltage is maintained at a temperature compensated target with a 1% tolerance. The charging current is compared to a predetermined minimum amplitude value and a third charging phase is started when the sequential charging current pulse equals the predetermined minimum amplitude value. During a third charging phase, predetermined charging current pulses having the predetermined minimum amplitude value are applied to the battery. The battery voltage is maintained at a temperature compensated target with a 1% tolerance.