Weldless battery pack

The present invention provides for a battery pack (50) comprising a plurality of cells (58) within a housing (52), each cell having a positive and negative terminals (57 and 59). The battery pack (50) further comprises molded-in circuitry means (54) on the surface of the housing (52) for providing interconnection between the plurality of cells (58). Optionally, the housing (52) further comprises molded-in or integral spring fingers (56). The spring fingers (56) are preferably biased toward the positive and negative terminals and provide at least some interconnection for the plurality of cells (58).

TECHNICAL FIELD 
This invention relates generally to battery cell packs, and more 
specifically to weldless battery packs. 
BACKGROUND 
Battery packs for portable devices such as two-way radios typically 
comprise a number of cells having contacts welded together all within a 
housing. The individual cells are interconnected using sheet metal tabs 
which are spot welded to the cell terminals. Usually, the interconnected 
cells are then spot welded to a flex circuit and subsequently inserted 
into a battery housing. This method of manufacture is wrought with 
inefficient assembly procedures and unnecessary parts and labor resulting 
in excessive manufacturing expense and comprised reliability. 
Consumer loaded batteries for consumer electronics such as cameras, radios, 
CD players, etc., typically have spring loaded contacts on one end and 
metal contacts coupled to the opposite end of the primary cells. Consumer 
loaded battery packs do not require the extra circuitry typically found in 
battery packs. Battery packs for portable radios will usually include 
resistors, thermistors, diodes and other components that enable the 
battery packs to be rechargeable and/or instrinsically safe. Thus, 
consumer loaded battery compartments may only have stamped metal on the 
housing and electrical loss between battery cells and circuitry is of 
little concern in these applications. Therefore, a need exists for a 
battery pack that provides the convenience of consumer loaded battery 
packs and allows for greater efficiency and reduced cost in assembly and 
manufacture. 
SUMMARY OF THE INVENTION 
Accordingly, a battery pack comprises a plurality of cells within a 
housing, each cell having a positive and negative terminal. The battery 
pack further comprises molded-in circuitry means on the surface of the the 
housing for providing interconnection between the plurality of cells. 
Optionally, the housing further comprises molded-in or integral spring 
fingers. The spring fingers are preferably biased toward the positive and 
negative terminals and provide at least some interconnection for the 
plurality of cells.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, there is shown a typical battery pack 10 as is known 
in the art. The battery pack 10 preferably comprises a battery housing 26 
having an aperture 25. Within the aperture 25, a flex circuit 24 is 
inserted having charger contacts for inserting into apertures 28. The 
battery housing 26 may optionally have a ventilation hole 29 for release 
of gases generated from the battery chemistry. Shock pads 14 and 22 are 
used to dampen the movement of the cells 18 when the battery pack 10 is 
dropped or receives a sudden impact. The cells 18 have their respective 
adjacent positive and negative terminals connected together via steel tabs 
20. The steel tabs are typically spot welded to the terminals and then 
welded or soldered to the contacts on the flex circuit 24. An insulator 16 
is placed between the cells and the shock pad 14 to assist in preventing 
shorts between the cells. Finally, a housing cover 12 is placed on top of 
the shock pad 14 to seal the assembly 10. 
Referring to FIG. 2, there is shown a battery pack 30 arranged and 
constructed in accordance with the present invention. The battery pack 30 
preferably comprises a housing 32 having an aperture 35 for receiving 
cells 38 and having apertures 36 serving as receptacles for charger 
contacts 46 molded in the I-beam frame 40. The battery housing 32 may 
optionally have a ventilation hole 34 for release of gases generated from 
the battery chemistry. I-beam frame 40 is arranged and constructed to 
retain cells 38 between an upper portion 44 and a lower portion 42. The 
I-beam frame is preferably made of a high temperature thermoplastic such 
as polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, 
polycarbonate, polyimide, and blends of these materials. Other 
thermoplastics and thermosets may be utilized to realize similar results. 
The I-beam frame 40 preferably further comprises integrally molded 
circuitry to couple the cell terminals. The charger contacts 46 are 
preferably metallized plastic protrusions extending from the top portion 
44. Methods of metallizing the protrusions are known to those skilled in 
the art. The cells can be retained in the I-beam frame 40 by using molded 
in or integral spring fingers (not shown) as seen in FIG. 3. 
Referring to FIG. 3, a battery pack 50 comprises a housing 52 having 
molded-in circuitry 54. The housing 52 and circuitry 54 are preferably 
made by one or two shot molding techniques as is known in the art. The 
molded-in or integral circuitry 54 couples to integral spring fingers 56 
that biases the spring finger contacts 55 towards the terminals (57 and 
59) of the battery cells 58. Once the batteries 58 are inserted in the 
battery housing 52 in the proper orientation, a housing cover 60 is used 
to seal the battery pack 50. Optionally, charger and battery contacts 
could be coupled to the molded in circuitry using metal filled through 
holes or other means known in the art. 
Referring to FIG. 4, a multiple I-beam frame 70 comprises a top substrate 
84 and a bottom substrate 86 coupled by I-beam structures 78 and end beams 
82. On the bottom surface of the top substrate 84 (not shown) and the top 
surface of the bottom substrate 86, molded-in or integral metallized 
spring fingers 72 are preferably located. Optionally, the spring fingers 
72 may be located on the bottom or top substrate alone. The spring finger 
72 preferably includes another metallization layer 74 to insure sufficient 
contact force with the terminals of the cells (not shown) to be inserted 
between the top and bottom substrates. Integral metallization (90) couples 
pairs of terminals together and preferably provides interconnections for 
componentry such as diodes, resistors and capacitors where needed. The 
components are placed in metallized through holes 76 for example. 
Metallized through holes 88 and 92 are used to interconnect terminals and 
other components if desired. Finally, metallized contacts 80 serve as the 
charger contacts. Likewise, charger contacts are provided in a similar 
fashion. The molded-in or integral metallization is preferably made using 
double-shot molding, but other means of providing interconnections on or 
in the I-beam structures, battery pack housing, or portable product 
housing is within contemplation of the present invention. 
In order to assemble the battery pack 10 of FIG. 1, approximately 70 
operations are needed in approximately 585 seconds. On the other hand, the 
battery pack 30 of FIG. 2 merely requires approximately 13 operations to 
assemble in approximately 50 seconds. This is a tremendous savings in 
labor and parts. In FIG. 3, the battery pack 50 can be assembled in the 
same time a consumer inserts batteries into their consumer electronic 
products. Additionally, this assembly can easily be adapted for robotic 
assembly.