Method for charging a battery using a constant current adapted to provide a constant rate of change of open circuit battery voltage

Abstract

A method for charging a battery is disclosed, wherein a constant current charging current is periodically adjusted as needed such that the change in battery voltage increases approximately linearly during the charging period. In some embodiments the charging is in three phases. An optional first phase charges with a low current until the battery voltages rises to a certain minimum. During a secondphase a constant current is provided while the battery voltage is monitored. The second phase constant current is periodically increased if the rate of change of battery voltage is less than a predetermined value and is decreased if the rate of change of battery voltage is more than the predetermined value. When the battery voltage attains a predetermined value, a third phase begins wherein a constant voltage is applied to the battery while the battery current draw is periodically monitored. Charging is stopped when the battery current draw falls to a predetermined value or, in some embodiments, when the charging current drops to a value that is a certain percentage of the charging current at the termination of phase two. In one embodiment the battery voltage is monitored to determine a possible battery failure, for example in the case of the battery voltage decreasing during the constant current charging of phase two. In some embodiments the battery is shorted out in response to detection of a possible failure.

Description

[0001] Kent Conahan [0002] Milton D Ribeiro [0003] Zhou Dongsheng [0004] Larry A. Klein [0005] Cross References to Related Applications [0006] THIS APPLICATION REQUIREMENTS FILLED ON FEBRUARY 12, 2007 VIA EXPRESS NO. ED354979677US, TO KENT CONAHAN, MILTON D. CHARGING A BATTERY USING A CONSTANTCURRENT ADAPTED TO PROVIDE A CONSTANT RATE OF CHANGE OF OPENCIRCUIT BATTERY VOLTAGE", which is hereby incorporated by reference in its entirety incorporated. [0007] copyright notice [0008] Portions of the disclosure of this patent document contain copyrighted material. The copyright owner has no objection to the reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. Background technique [0009] As consumer electronics are increasingly powered by rechargeable batteries, it becomes important to provide means for recharging th...

AI Technical Summary

Problems solved by technology

Also, after many charge / discharge cycles, when damaged or when cold, the same given battery will have less energy available (and require a correspondingly less rapid charge profile )

Therefore, the CC / CV charging method may undercharge or take longer than needed for some specific battery cells, or may overcharge or charge other cells too quickly, thus causing them to be damaged, which shortens the battery life and give users a less satisfactory experience

Images