NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Battery Cell By-Pass CircuitThe invention is a circuit and method of limiting the charging current voltage from a power supply net work applied to an individual cell of a plurality of cells making up a battery being charged in series. It is particularly designed for use with batteries that can be damaged by overcharging, such as Lithium-ion type batteries. In detail. the method includes the following steps: 1) sensing the actual voltage level of the individual cell; 2) comparing the actual voltage level of the individual cell with a reference value and providing an error signal representative thereof; and 3) by-passing the charging current around individual cell necessary to keep the individual cell voltage level generally equal a specific voltage level while continuing to charge the remaining cells. Preferably this is accomplished by by-passing the charging current around the individual cell if said actual voltage level is above the specific voltage level and allowing the charging current to the individual cell if the actual voltage level is equal or less than the specific voltage level. In the step of bypassing the charging current, the by-passed current is transferred at a proper voltage level to the power supply. The by-pass circuit a voltage comparison circuit is used to compare the actual voltage level of the individual cell with a reference value and to provide an error signal representative thereof. A third circuit, designed to be responsive to the error signal, is provided for maintaining the individual cell voltage level generally equal to the specific voltage level. Circuitry is provided in the third circuit for bypassing charging current around the individual cell if the actual voltage level is above the specific voltage level and transfers the excess charging current to the power supply net work. The circuitry also allows charging of the individual cell if the actual voltage level is equal or less than the specific voltage level.
Document ID
20010111086
Document Type
Other - Patent
External Source(s)
NPO-30305-1T
Authors
Susan J Mumaw
(Jet Propulsion Laboratory La Cañada Flintridge, United States)
Jeffrey Evers
(Jet Propulsion Laboratory La Cañada Flintridge, United States)
Calvin L Craig
(Jet Propulsion Laboratory La Cañada Flintridge, United States)
Stuart D Walker
(Jet Propulsion Laboratory La Cañada Flintridge, United States)
Date Acquired
August 20, 2013
Publication Date
April 3, 2001
Publication Information
Publisher: United States Patent and Trademark Office
Subject Category
Electronics And Electrical Engineering
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-Patent-6,211,650
Patent Application
US-Patent-Appl-SN-482150
No Preview Available