Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Plural cells
Reexamination Certificate
2002-06-27
2003-11-11
Abrams, Neil (Department: 2839)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Plural cells
Reexamination Certificate
active
06645669
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to battery packs and a method for constructing the same.
Referring to
FIG. 3
, battery pack
10
typically has rechargeable cells
11
connected in series and/or parallel via connectors, such as metal straps
13
. The cells
11
may be held together by a plenum or plate
12
. The straps
13
may be disposed between the plate
12
and cells
11
. Alternatively, plate
12
may be disposed between cells
11
and straps
13
, whereas the straps
13
contact the cells
11
through holes in plate
12
.
This assembly is then disposed in a housing
15
. Cables or wires connected to cells
11
may extend into a terminal block
14
, which allows the battery pack
10
to be connected to electric and/or electronic devices such as power tools, chargers, cellular telephones, etc.
Referring to
FIGS. 1 and 3
, typical cells
11
include cells produced by Sanyo Energy, such as model no. N2400. Such cells
11
may have weld area
11
W, where the negative collector inside the cell is welded to the exterior can during the production of cell
11
. This process may be done from the outside of the cell
11
using a laser. After the weld is completed, a weld area
11
W having a diameter of about 4 or 5 millimeters is left. This weld area
11
W may be sensitive to exterior pressure, heat, and electrical current.
During the construction of battery pack
10
, cells
11
are typically welded together using double protrusion nickel straps
13
, which have protrusions
13
P. During the welding process, a strap electrode
16
S is disposed on strap
13
while cell electrode
16
contacts the cell
11
directly. Current is passed through strap electrode
16
S, strap
13
and out the cell
11
into cell electrode
16
C, resulting in heat and finally welding.
This is problematic because cell electrode
16
C partially or completely contacts weld area
11
W of cell
11
. This welding process may result in early cell failure.
SUMMARY OF THE INVENTION
An improved battery pack is proposed. The battery pack comprises a housing, and first and second cells disposed in the housing, the first cell having a radius and a periphery. In addition, the battery pack comprises a metal strap connecting the first and second cells, the strap having an end disposed over the first cell and a portion of the periphery, and two contact protrusions contacting the first cell, wherein distance between the strap end and the overlaped periphery is greater than the radius of the first cell.
Also disclosed is a method for manufacturing a battery pack comprising the steps of providing two cells, at least one cell having a weld area, welding a strap therebetween, and disposing the cells in a housing, wherein the strap is welded by disposing a first electrode on the strap and a second electrode on the at least one cell outside of the weld area, and providing a current between the first and second electrodes.
Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below.
REFERENCES:
patent: 2575976 (1951-11-01), Rock
patent: 3427202 (1969-02-01), Wilke
patent: 3810790 (1974-05-01), Denis
patent: 5308717 (1994-05-01), Gordin
patent: 5607793 (1997-03-01), Alexandres et al.
Casalena Adam M.
White Daniel J.
White Paul S.
Abrams Neil
Ayala Adan
Black & Decker Inc.
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