Cell monitoring and balancing

• US 8,274,261 B2
• Filed: 07/10/2008
• Issued: 09/25/2012
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Seman, Andrew E. Jr., Cruise, Nathan, White, Daniel J., Carrier, David A., Brotto, Daniele C., Qin, Fugen, Trinh, Dahn
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): TORRES RUIZ, JOHALI ALEJANDRA
• Application Number:
  US12/170,718
• Publication Number:
  US 20090015206A1
• Time in Patent Office: 1,538 Days
• Field of Search: 320/122, 320/134
• US Class Current: 320/134
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for monitoring the voltage of each of a plurality of cells of a battery pack is provided. The method may include monitoring a voltage potential for each of a plurality of cells in a battery pack utilizing a single channel of battery control unit within the battery pack. If, during discharge of the battery, e.g., the battery is being used to power a hand tool, the voltage potential of any cell is determined by the battery control unit to be below a predetermined minimum voltage, the battery control unit discontinues a current flow from battery pack to the tool. Additionally, during charging of the battery pack, if a voltage differential between any one of the cells and any other one of the cells is determined to be above a predetermined maximum differential, the battery control unit reduces the voltage potential stored in the cell having the higher voltage potential.

Claims

1. A method for monitoring the voltage of each of a plurality of cells of a battery pack, comprising:

monitoring a voltage potential for each of a plurality of cells in a battery pack utilizing a single channel of a battery control unit within the battery pack;

discontinuing current flow from battery pack when the voltage potential of any cell is determined by the battery control unit to be below a predetermined minimum voltage during discharge of the battery pack; and

reducing the voltage potential stored in any one or more of the cells when a voltage differential between the respective one or more cells and any other one of the cells having a lesser voltage potential is determined by the battery control unit to exceed a predetermined maximum differential during charging of the battery pack;

wherein monitoring the voltage potential for the plurality of cells comprises;

measuring a cumulative voltage potential across all of the cells as the battery pack is discharging;

measuring a cumulative voltage across a sub-set of the cells, the sub-set comprising N number of the cells where the number N is evenly dividable into the total number of cells;

dividing the cumulative voltage potential of all the cells by N to determine a calculated voltage across the sub-set of the cells; and

comparing the measured voltage across the sub-set of the cells with the calculated voltage across the sub-set of the cells to obtain a voltage differential.

2. The method of claim 1, further comprising terminating the discharging of the battery pack if the voltage differential is greater than a predetermined threshold.