Battery pack and internal component arrangement within the battery pack for cordless power tool system

1. A battery pack for a cordless power tool, comprising:

a top housing supporting an electronic module and a battery terminal block connected to the electronics module, and

a bottom housing containing a plurality of battery cells constrained between a pair of end caps, wherein each end cap includes a plurality of voltage sense wires extending across an outer surface thereof and electrically connected between a corresponding cell and the electronics module.

2. The battery pack of claim 1 , wherein each end cap includes an integrated connector receiving a first end of each sense wire for connection to a corresponding connector of a wiring harness that is attached to the electronics module so as to connect the sense wires to the module.

3. The battery pack of claim 2 , wherein the first end of each sense wire is a rounded pin connector received within the integrated connector of the end caps so as to connect to a round pin female connector connected to the wiring harness.

4. The battery pack of claim 1 , wherein each end cap has a plurality of recesses formed on an inner surface thereof, each recess containing either a cell strap or a power terminal lead therein for electrically connecting the cells to the electronics module.

5. The battery pack of claim 4 , wherein the cell strap or power terminal lead contained are impressed within each of the recesses for connecting the cells to the electronic module.

6. The battery pack of claim 4 , wherein one or more of the cell straps and power terminal leads contained within each recesses are composed of a first metal material that is subject to an annealing process to improve ductility, or composed a second metal material having a lower hardness but a higher ductility than the first material.

7. The battery pack of claim 4 , wherein one or more of the cell straps has a jogged slit extending from an open end along a path having at least one angular directional change defining a positive leg and a negative leg therebetween.

8. The battery pack of claim 4 , wherein each end cap includes a plurality of spaced access holes therethrough, and including a plurality of one of resistance welding and laser welding areas within each recess electrically connecting groups of cells or power terminal leads to the electronics module via the cell straps and power terminal leads.

9. The battery pack of claim 4 , wherein

each end cap includes a plurality of spaced access holes therethrough, and a plurality of welded areas each within a corresponding access hole connecting the cell strap or power terminal lead contained within each recess with groups of cells, and each sense line has a second coil spring end which extends through a corresponding access hole to be seated at a junction of a cell strap and battery cell exposed through the access hole so as to provide sensed data from the cell to the electronics module via the integrated connector.

10. The battery pack of claim 9 , wherein a given sense line spring end is retained by a chamfered ridge formed around its corresponding access hole so that the spring end maintains contact with its cell/strap junction.

11. The battery pack of claim 10 , wherein a given sense line spring end is compressed between a surface of its corresponding cell/strap junction and its corresponding chamfered ridge.

12. The battery pack of claim 9 , wherein each sense line spring end is a pressure contact to a cell/strap junction so as to require no welding thereto.

13. The battery pack of claim 1 , wherein each given sense line is constrained within a formed channel in the outer surface of its corresponding end cap.

14. The battery pack of claim 13 , wherein each end cap includes a plurality of spaced-apart formed tabs extending along the length of each of the channels for securing the sense wires within corresponding channels of the end cap outer surface.

15. The battery pack of claim 1 , wherein the electronics module comprises a potting boat housing a printed circuit board (PCB) with electronic components thereon, and wherein the potting boat serves as a heat sink for the electronics module.

16. The battery pack of claim 15 , wherein the top housing includes an upper portion having an interior recessed area for receiving the electronics module, and the potting boat is secured in an inverted position within the interior recessed area so that electronic components on the PCB face down toward the battery cells.

17. The battery pack of claim 1 , wherein each of the top housing and bottom housing have a plurality of screw bosses around a periphery thereof which align to provide bores for fasteners to secure the top and bottom housings together, and wherein one or more of the bores includes a vibration dampening component therein.

18. The battery pack of claim 1 , wherein the top housing has a plurality of vents therein to provide heat dissipation from an interior of the pack to the exterior.

19. The battery pack of claim 1 , wherein each end cap includes a plurality of vents along a periphery thereof to provide heat dissipation from the cells.

20. The battery pack of claim 1 , wherein the battery pack includes a plurality of spaced apart ribs around an inner periphery on sidewalls of the bottom housing contacting the cells therein at multiple points of contact with the cells to spread loading on the cells due to vibration of the pack or a drop impact to the pack.

21. The battery pack of claim 1 , wherein the battery pack includes a plurality of spaced apart separator ribs on an inner bottom surface of the bottom housing providing mechanical support to constrain the cells.

22. The battery pack of claim 1 , wherein an interior surface of the top housing includes a plurality of ribbed extensions and each end cap includes a plurality of formed raised projections on an upper surface thereof which abut the ribbed extensions when the top and bottom housings are secured together.

23. The battery pack of claim 1 , wherein only the end caps require re-tooling to accommodate different sized cells from differing manufacturers so that the bottom housing of the pack does not have to be retooled to accommodate the different cell sizes.

24. An internal component arrangement within a battery pack of a cordless power tool, the pack having a top housing and a bottom housing, comprising:

a plurality of battery cells disposed in the bottom housing,

a pair of end caps constraining the cells between inner surfaces of the end caps, and

a plurality of voltage sense wires extending across an outer surface of each end cap, each sense line having a first end electrically connected to an electronics module in the top housing and a second end electrically connected to a corresponding cell between the end caps.

25. The arrangement of claim 24 , wherein each end cap has a plurality of recesses formed on an inner surface thereof, each recess containing either a cell strap or a power terminal lead impressed therein for electrically connecting the cells to the electronics module.

26. The arrangement of claim 24 , wherein each end cap includes a plurality of spaced access holes there through, with the cell straps and power terminal leads being attached to the cells through corresponding access holes.

27. The arrangement of claim 26 , further including a plurality of welded areas, each within a corresponding access hole, connecting by one of resistance welding and laser welding the cell straps and power terminal leads to the corresponding cells.

28. The arrangement of claim 26 , wherein

each end cap includes a first connector receiving a first end of each of the sense wires for connection to a corresponding second connector attached to a wiring harness of the electronics module, and

each sense line has a second coil spring end which extends through a corresponding access hole to contact a given cell strap/battery cell junction so as to provide sensed data from a given cell to the electronics module via the first and second connectors and wiring harness.

29. The arrangement of claim 28 , wherein each access hole includes a chamfered ridge around a circumference thereof, and each given spring end is retained by the chamfered ridge so that the spring end maintains contact with its corresponding cell strap/battery cell junction.

30. The arrangement of claim 24 , wherein

each given sense line is constrained within a formed channel in the outer surface of its corresponding end cap, and

each end cap includes a plurality of spaced-apart formed tabs extending along the length of each of the channels for securing the sense wires within corresponding channels of the end cap outer surface.

31. A method of arranging a plurality of internal components within a battery pack housing, comprising:

providing a pair of end caps, each end cap having a plurality of spaced apart recesses formed on an inner surface thereof which are shaped to receive a plurality of cell straps and a pair of power terminal leads, each end cap having a plurality of spaced apart access holes which extend through a given recess,

placing the cell straps and leads within the spaced apart recesses so that a portion of the cell strap or power lead is exposed through a corresponding access hole,

disposing a plurality of cylindrical battery cells between the end caps so that ends of corresponding cells contact a given cell strap or lead at a junction that is exposed through a corresponding access hole, wherein sides of the end caps have a scalloped shape that conforms to the rounded shape of the cylindrical cells to constrain the cells there between,

welding the cell straps and power leads to the cells through the access holes to form a core pack comprised of the cells connected to the straps and leads between the end caps,

attaching a plurality of voltage sense wires within outer surfaces of the end caps in the core pack, wherein one end of each sense line is a spring end which is retained within a corresponding access hole of the core pack to contact a junction of a cell strap/battery cell, and the other end of each sense line is attached to a integrated connector formed in each end cap of the core pack, and inserting the core pack into the housing.