IP Library › Granted Patent US 7,928,691
Granted Patent B2
US 7,928,691 · App. 11/163,668 · Granted Apr 19, 2011

Method and system for cell equalization with isolated charging sources

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 7,928,691
App. No.
11/163,668
Granted
Apr 19, 2011
Kind
B2
Abstract

A system and method for charging a rechargeable, or secondary, battery including a series string of battery cells, a topology of charging sources that selectively provides charging current to battery cells that need to be charged, but avoids overcharging battery cells that are already charged above a predetermined voltage threshold. Based on individual cell voltage measurements, the charging current is controlled in a manner to direct charging current to the battery cell(s) needing charge until these cells are fully charged, and bypasses battery cells that are fully charged or become fully charged.

Claims (47)

1. A charging system for charging a rechargeable battery connected to a load, comprising:

N battery cells coupled in series forming a series string, wherein said series string comprises:

a first battery cell coupled to the load, and

an N th battery cell coupled to a ground of the load;

a plurality of isolated charging sources, each isolated charging source being coupled to a power source and coupled in parallel to one of the battery cells of said series string, wherein each isolated charging source is configured to operate in one of a first state and a second state, wherein when operating in said first state the isolated charging source provides charging current to said respective battery cell, and when operating in said second state, the isolated charging source does not provide charging current to said respective battery cell;

a plurality of positive paths coupled to said series string and said isolated charging sources; and

a plurality of negative paths coupled to said series string and said isolated charging sources, wherein each of the isolated charging sources are coupled in parallel to one of the respective battery cells via a respective positive path of the plurality of positive paths and a respective negative path of the plurality of negative paths, and wherein a ground of the power source is isolated from the ground of the load.

2. The charging system of claim 1 , wherein each isolated charging source is configured to provide charging current to each respective battery cell via said positive path, and return charging current to said isolated charging source via said negative path, and wherein each isolated charging source comprises a DC to DC converter configured as a constant voltage source for cell equalization.

3. The charging system of claim 1 , further comprising:

a controller, where said controller is coupled to each of said isolated charging sources.

4. The charging system of claim 3 , wherein said controller is configured to selectively operate each isolated charging source in one of said first state and said second state.

5. The charging system of claim 1 , further comprising:

a plurality of cell monitors coupled to said series string, wherein each cell monitor is coupled to a respective battery cell, and is configured to measure a voltage of the respective battery cell; and

a controller coupled to each cell monitor and coupled to each isolated charging source, wherein said isolated charging sources are controlled by said controller to provide charging current to their respective battery cells when said battery cell has a voltage less than a threshold amount, and to not provide charging current to said battery cell when said battery cell has a voltage equal to or greater than said threshold amount.

6. A method for cell equalization of a secondary battery being charged, the method comprising the steps of:

coupling N battery cells in series to form a series string, wherein said coupling N battery cells step comprises the steps of:

coupling a first cell to a load, and

coupling an N th battery cell to a ground of the load;

coupling a plurality of isolated charging sources to said series string, wherein each isolated charging source is coupled in parallel across one of said N battery cells;

coupling each of the plurality of isolated charging sources to a power source, wherein a ground of the power source is isolated from the ground of the load; and

configuring said isolated charging sources to operate either in a first state to provide charging current to said battery cell or in a second state to not provide charging current to said battery cell to selectively provide charging current to one or more of said N battery cells, wherein each of the isolated charging sources comprises a DC to DC converter for providing a constant voltage during cell equalization.

7. The method of claim 6 , wherein said configuring said isolated charging sources step comprises the steps of:

configuring a particular isolated charging source to operate in a first state to provide charging current to said respective battery cell; and

configuring each isolated charging source to operate in a second state to not provide charging current to said one or more of said N battery cells.

8. The method of claim 6 , further comprising the steps of:

configuring said isolated charging sources to provide charging current to each battery cell having a voltage less than a threshold amount, and to not provide charging current to each battery cell having a voltage equal to or greater than said threshold amount.

9. The method of claim 8 , further comprising the steps of:

coupling a plurality of cell monitors to said series string to monitor a voltage of each of said N battery cells, determine which of said N battery cells has a voltage greater than or equal to said threshold amount, and determine which of said N battery cells has a voltage less than said threshold amount.

10. A method for equalizing the cell voltage of a secondary battery comprising the steps of:

coupling two or more battery cells in series to form a series string, wherein one of the battery cells is coupled to a load and another of the battery cells is coupled to a ground of the load;

coupling in parallel across each battery cell an associated isolated charging source, each of said isolated charging sources connected to a power source, wherein a ground of the power source is isolated from the ground of the load;

configuring said associated isolated charging source to operate either in a first state to provide a charging current to said battery cell or in a second state to not provide a charging current to said battery cell, wherein each isolated charging source is configured to operate as a constant voltage source during cell equalization;

providing a charging current to any battery cell having a voltage less than a threshold level with a respective associated isolated charging source;

not providing the charging current to any battery cell having a voltage equal to or greater than said threshold level; and

providing a constant voltage to each of the two or more battery cells via the associated isolated charging sources.

11. The method of claim 10 , wherein said step of providing a charging current to comprises the steps of:

switching ON the respective isolated charging source to provide the charging current to the associated battery cell having a voltage less than said threshold level; and

switching OFF said respective isolated charging source to avoid overcharging said associated battery cell when said associated battery cell has a voltage greater than said threshold level.

12. The method of claim 10 , further comprising the steps of:

monitoring a respective voltage level of each of said battery cells; and

independently operating each of said isolated charging sources in an ON state or an OFF state based on said respective voltage level of each of said battery cells.

13. The method of claim 10 , wherein said step of providing a charging current to a battery cell further comprises the step of:

returning said charging current to said respective associated isolated charging source via a negative path.

14. The method of claim 10 , further comprising the steps of:

monitoring a respective voltage of each of said N battery cells;

determining which of said N battery cells has a voltage greater than or equal to said threshold level; and

determining which of said N battery cells has a voltage less than said threshold level.

Assignments (27)
PATENT SECURITY AGREEMENT Recorded Oct 17, 2023
From: TUTHILL ACQUISITION LLC; EPV BUYER, INC.; EPV INTERMEDIATE, LLC
To: VECTRA CO.; DUKE INTERMEDIATE HOLDINGS, LLC; DUKE FINANCE HOLDINGS, LLC; DUKE FINANCE, LLC; DUKE FINANCE SUBSIDIARY HOLDINGS, LLC; OM GROUP CORPORATE, LLC; OMG ENERGY HOLDINGS, INC.; LITHIUMSTART INC.; EAGLEPICHER ELECTRONIC PACKAGING, LLC; EAGLEPICHER TECHNOLOGIES, LLC; EP INTERMEDIATE HOLDINGS I, LLC; EP INTERMEDIATE HOLDINGS II, LLC; BANK OF AMERICA, N.A.
Reel/Frame 065247/0032 →
RELEASE OF SECURITY INTEREST Recorded Oct 13, 2023
From: GENERAL ELECTRIC CAPITAL CORPORATION
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 065231/0344 →
RELEASE AND TERMINATION OF LIEN ON PATENTS (1L) Recorded Oct 12, 2023
From: JEFFERIES FINANCE LLC
To: VECTRA CO.; EAGLEPICHER TECHNOLOGIES, LLC; DUKE FINANCE SUBSIDIARY HOLDINGS, LLC
Reel/Frame 065221/0832 →
RELEASE AND TERMINATION OF LIEN ON PATENTS (2L) Recorded Oct 12, 2023
From: JEFFERIES FINANCE LLC
To: VECTRA CO.; EAGLEPICHER TECHNOLOGIES, LLC; DUKE FINANCE SUBSIDIARY HOLDINGS, LLC
Reel/Frame 065222/0001 →
FIRST LIEN INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded Mar 9, 2018
From: EAGLEPICHER TECHNOLOGIES, LLC
To: JEFFERIES FINANCE LLC
Reel/Frame 045545/0508 →
SECOND LIEN INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded Mar 9, 2018
From: EAGLEPICHER TECHNOLOGIES, LLC
To: JEFFERIES FINANCE LLC
Reel/Frame 045545/0893 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS (FIRST LIEN) Recorded Mar 8, 2018
From: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 045539/0138 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS (SECOND LIEN) Recorded Mar 8, 2018
From: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 045539/0225 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS (SECOND LIEN) Recorded Feb 22, 2017
From: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 041777/0090 →
SECURITY INTEREST Recorded Jan 8, 2016
From: EAGLEPICHER TECHNOLOGIES, LLC
To: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH, AS COLLATERAL AGENT
Reel/Frame 037459/0921 →
SECURITY INTEREST Recorded Dec 16, 2015
From: EAGLEPICHER TECHNOLOGIES, LLC
To: CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH, AS COLLATERAL AGENT
Reel/Frame 037311/0571 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS Recorded Oct 28, 2015
From: PNC BANK
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 036985/0642 →
SECURITY AGREEMENT Recorded Sep 12, 2013
From: OM GROUP, INC.; OMG ELECTRONIC CHEMICALS, LLC; OMG AMERICAS, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EAGLEPICHER MEDICAL POWER, LLC
To: PNC BANK
Reel/Frame 031208/0876 →
RELEASE OF SECURITY INTEREST Recorded Sep 5, 2013
From: BANK OF AMERICA, N.A.
To: OM GROUP, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EAGLEPICHER MEDICAL POWER, LLC; OMG AMERICAS, INC.; OMG ELECTRONIC CHEMICALS, LLC
Reel/Frame 031169/0976 →
SECURITY AGREEMENT Recorded Aug 12, 2011
From: OM GROUP, INC., A DELAWARE CORPORATION; COMPUGRAPHICS U.S.A. INC., A DELAWARE CORPORATION; CYANTEK CORPORATION, A DELAWARE CORPORATION; OMG AMERICAS, INC., A OHIO CORPORATION; OMG ELECTRONIC CHEMICALS, LLC, A DELAWARE LIMITED LIABILITY COMPANY; OMG ENERGY HOLDINGS, INC., A DELAWARE CORPORATION; OMG HARKO HOLDINGS, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER MEDICAL POWER, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER TECHNOLOGIES, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EPEP HOLDING COMPANY, LLC, A DELAWARE LIMITED LIABILITY COMPANY
To: BANK OF AMERICA, N.A., AS COLLATERAL AGENT
Reel/Frame 026740/0353 →
PATENT RELEASE AGREEMENT Recorded Aug 10, 2011
From: PNC BANK, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT
To: OM GROUP, INC., A DELAWARE CORPORATION; OMG AMERICAS, INC., A OHIO CORPORATION; OMG ELECTRONIC CHEMICALS, INC., A DELAWARE LIMITED LIABILITY COMPANY; COMPUGRAPHICS U.S.A. INC., A DELAWARE CORPORATION; OMG ENERGY HOLDINGS, INC., A DELAWARE CORPORATION; EAGLEPICHER TECHNOLOGIES, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EPEP HOLDING COMPANY, LLC, A DELAWARE LIMITED LIABILITY COMPANY; EAGLEPICHER MEDICAL POWER, LLC, A DELAWARE LIMITED LIABILITY COMPANY
Reel/Frame 026727/0485 →
SECURITY AGREEMENT Recorded Mar 11, 2010
From: OM GROUP, INC.; OMG AMERICAS, INC.; OMG ELECTRONIC CHEMICALS, INC.; COMPUGRAPHICS U.S.A. INC.; OM HOLDINGS, INC.; OMG ENERGY HOLDINGS, INC.; EAGLEPICHER TECHNOLOGIES, LLC; EPEP HOLDING COMPANY, LLC; EAGLEPICHER MEDICAL POWER, LLC
To: PNC BANK, NATIONAL ASSOCIATION
Reel/Frame 024066/0130 →
PARTIAL RELEASE OF AMENDED AND RESTATED PATENT SECURITY AGREEMENT RECORDED AT REEL 020723 FRAME 0038. Recorded Jan 29, 2010
From: OBSIDIAN, LLC AS COLLATERAL AGENT
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 023892/0847 →
PARTIAL RELEASE OF AMENDED AND RESTATED PATENT SECURITY AGREEMENT RECORDED AT REEL 020710/FRAME 0871 Recorded Jan 29, 2010
From: GENERAL ELECTRIC CAPITAL CORPORATION, AS COLLATERAL AGENT
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 023870/0428 →
SHORT FORM INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded Mar 28, 2008
From: EAGLEPICHER CORPORATION; HILLSDALE AUTOMOTIVE, LLC; EP MINERALS, LLC; WOLVERINE ADVANCED MATERIALS, LLC; EAGLEPICHER TECHNOLOGIES, LLC
To: OBSIDIAN, LLC, AS COLLATERAL AGENT
Reel/Frame 020723/0038 →
SHORT FORM INTELLECTUAL PROPERTY SECURITY AGREEMENT Recorded Mar 28, 2008
From: EAGLEPICHER CORPORATION; HILLSDALE AUTOMOTIVE, LLC; EP MINERALS, LLC; WOLVERINE ADVANCED MATERIALS, LLC; EAGLEPICHER TECHNOLOGIES, LLC
To: GENERAL ELECTRIC CAPITAL CORPORATION, AS COLLATERAL AGENT
Reel/Frame 020710/0871 →
CHANGE OF NAME Recorded Mar 22, 2008
From: NEW EAGLEPICHER TECHNOLOGIES, LLC
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 020679/0946 →
RELEASE OF SECURITY INTEREST Recorded Feb 8, 2008
From: GOLDMAN SACHS CREDIT PARTNERS, LP
To: EAGLEPICHER CORPORATION (F/K/A NEW EAGLEPICHER CORPORATION); HILLSDALE AUTOMOTIVE, LLC; EAGLEPICHER TECHNOLOGIES, LLC (F/K/A NEW EAGLEPICHER TECHNOLOGIES, LLC); WOLVERINE ADVANCED MATERIALS, LLC; EAGLEPICHER MANAGEMENT COMPANY
Reel/Frame 020478/0657 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Aug 30, 2006
From: EAGLEPICHER TECHNOLOGIES LLC
To: NEW EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 018184/0689 →
SECURITY AGREEMENT Recorded Aug 7, 2006
From: HILLSDALE AUTOMOTIVE, LLC; NEW EAGLEPICHER TECHNOLOGIES, LLC; WOLVERINE ADVANCED MATERIALS, LLC; EAGLEPICHER MANAGEMENT COMPANY
To: GENERAL ELECTRIC CAPITAL CORPORATION
Reel/Frame 018061/0210 →
SECOND LIEN PATENT SECURITY AGREEMENT Recorded Aug 7, 2006
From: HILLSDALE AUTOMOTIVE, LLC; NEW EAGLEPICHER TECHNOLOGIES, LLC; WOLVERINE ADVANCED MATERIALS, LLC; EAGLEPICHER MANAGEMENT COMPANY
To: GOLDMAN SACHS CREDIT PARTNERS L.P.
Reel/Frame 018061/0255 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Oct 26, 2005
From: STUDYVIN, WILLIAM; COATNEY, ERIC; PENNOCK, TIM; SHIMP, PHILLIP; MILLER, GREG
To: EAGLEPICHER TECHNOLOGIES, LLC
Reel/Frame 016690/0058 →