Electricity: measuring and testing – Electrolyte properties – Using a battery testing device
Reexamination Certificate
1998-05-29
2001-02-20
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Electrolyte properties
Using a battery testing device
C324S434000, C320S122000
Reexamination Certificate
active
06191591
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a test unit for grading battery cells.
In order to assemble battery packs employing multiple cells made of, for example, a series and/or series parallel connection of individual secondary cells, the cells should have substantially the same capacity. However, NiCd or metal hydride batteries can display different discharge characteristics from one another upon manufacturing. Thus, it is desirable to grade the cells prior to battery pack assembly to assure that the cells have substantially the same capacity, particularly when in a series interconnection, so that one cell, which may have less capacity than the other, does not disable or otherwise reduce the capacity of the entire battery pack.
In the past, in order to grade the cells, a test fixture has been employed for holding cells which have been fully charged, coupling them in series, and loading and discharging them through a resistive load. Such fixtures hold, for example, an array of one hundred cells with the operator inserting the cells into the test fixture to begin their discharge. Periodically, and typically on a two-minute basis, an operator utilizes a voltage test probe to test each cell. The probe provides an audible or visible indication that a cell has fallen below a predetermined reference voltage, such as 1.3 volts for a 1.5 volt cell. Thus, the operator must periodically manually test each of the hundred cells and, if a cell has fallen below the threshold voltage, the test probe will provide the operator with an indication that the cell has reached a lowered voltage. When a cell falls below the threshold voltage, it is then removed, which interrupts the series circuit of the test fixture, and the last most cell is repositioned in the removed cell's location to continue the series discharge circuit. As can be appreciated as more and more cells reach a diminished capacity, the shuffling and reshuffling of batteries becomes a labor intensive and inefficient process by which to grade cells.
SUMMARY OF THE PRESENT INVENTION
In order to overcome the deficiencies of the prior art cell grading process and test equipment, the cell grading test fixture of the present invention includes a plurality of cell sockets for receiving individual cells, with the sockets being electrically interconnected in series so that current through the entire array of cells flows through each of the cells once inserted into the fixture. Associated with each socket is an indicator which indicates to the operator when a cell voltage has fallen to a predetermined level. Each socket of the test fixture includes an electrical contact which is spring-loaded and movable such that upon removal of a cell which has dropped below a threshold voltage, the movable contact engages the contact of an adjacent socket, in effect shorting out the cell location such that the series circuit of cells continues to provide a current path for the remaining cells. A plurality of voltage comparators are coupled to each of the cells and compares the voltage of the cell to a reference voltage. When the cell voltage drops below the predetermined voltage, the indicator, such as an LED mounted to the test fixture immediately adjacent the cell, is illuminated to indicate to the operator that the cell has reached a reduced voltage and should be removed.
Thus, with the cell grading fixture of the present invention, the operator can insert an array of cells for testing and watch the test fixture until such time as cells begin to drop below the threshold voltage, which is indicated by an LED immediately adjacent the individual cell. At such time, the cell is removed and, knowing the time duration it took from the initiation of the testing procedure until the cell reached its lower threshold voltage, the cells can be automatically graded without reshuffling them in the test fixture. Such a test fixture and the method of testing cells greatly improves the efficiency of grading cells and allows a single operator to test multiple cell banks at a given time as opposed to being occupied with the shuffling of cells in a single test fixture.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.
REFERENCES:
patent: 705919 (1902-07-01), Gill
patent: 1102355 (1914-07-01), Rawson et al.
patent: 3454859 (1969-07-01), Ford et al.
patent: 3586962 (1971-06-01), Rebstock
patent: 3735310 (1973-05-01), Kochanski
patent: 3887393 (1975-06-01), La Rue, Jr.
patent: 4081743 (1978-03-01), Madden
patent: 4198597 (1980-04-01), Sawyer
patent: WO 88/04776 (1988-06-01), None
Coyle Harold T.
Delgado Julio
Ratajczak Joseph S.
Rockett Danny F.
Deb Anjan K
Hanson Sven W.
Metjahic Safet
Moltech Power Systems, Inc.
Nicol Jacqueline M.
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