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:
Nov. 04, 1997
Filed:
Nov. 17, 1995
Douglas James Millar, Vancouver, WA (US);
Sharp Microelectronics Technology, Inc., Camas, WA (US);
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
A voltage gradient measurement device is provided for determining the remaining lifetime of a battery used to power a radio, pager, cellular telephone, or similar device. The battery is attached to a first circuit element to obtain a history of the battery voltage which is used to determine the differential battery voltage. The battery is also attached to a second circuit element which measures the voltage margin between the battery voltage and a reference voltage representing the battery end-of-life condition. A third circuit element divides the voltage margin output of the second circuit element by the differential battery voltage output of the first circuit element to estimate the time that will elapse until the battery voltage approximately equals the reference end-of-life voltage level. This time estimate is used as a basis for performing a variety of functions, including a trigger for a battery shut-off switch to protect radio circuits, and as an activator of indicators to warn the battery user of approaching battery safety thresholds. A method of estimating the remaining useful life of the battery is also disclosed.