Battery pack assembly with integrated heater

Abstract

A battery pack assembly for providing electric power to a load includes a battery pack, preferably made up of a plurality of lithium ion cells. A heating device formed of a flexible material flexes and covers at least part of the battery pack. The heating device includes a meandering heating strip. A thermal sensor is surrounded by the heating strip to sense the temperature of the battery pack. Electric current is applied to the heating strip to heat the battery pack when its temperature falls too low, thus improving performance of the battery pack. The heating device also includes a plurality of tabs extending beyond the peripheral sides of the heating device for direct connection to the cells. Thus, electric current for the heating strip is provided directly from the cells of the battery pack.

What is claimed is: 
     
         1 . A method of heating a battery assembly, the method comprising:
 electrically interconnecting a first grouping of battery cells in parallel;   electrically interconnecting a second grouping of battery cells in parallel;   electrically interconnecting the first grouping of battery cells and the second grouping of battery cells in series;   positioning the first grouping of battery cells and the second grouping of battery cells between a first non-conductive component and a second non-conductive component, the first non-conductive component and the second non-conductive component being disconnectable to allow access to the battery pack;   positioning a heating device to overlap at least a portion of the first grouping of battery cells and a portion of the second grouping of battery cells; and   electrically interconnecting the heating device with the first grouping of battery cells and the second grouping of battery cells to apply power from the first grouping of battery cells and the second grouping of battery cells to the heating device.   
     
     
         2 . The method of  claim 1 , wherein the heating device includes connection pads and the method further comprises the step of electrically interconnecting the connection pads to the battery pack. 
     
     
         3 . The method of  claim 2 , wherein the heating device includes a heating strip and the method further comprises the step of electrically interconnecting the heating strip to the battery pack. 
     
     
         4 . The method of  claim 3 , wherein the heating strip is electrically interconnected to the battery pack through the connection pads. 
     
     
         5 . The method of  claim 4 , further comprising the steps of:
 coupling the connection pads to a printed circuit board; and   coupling the heating strip to a printed circuit board, the heating strip being electrically interconnected to the connection pads through the printed circuit board.   
     
     
         6 . The method of  claim 1 , wherein the heating device includes a heating strip and the method further comprises the step of electrically interconnecting the heating strip to the battery pack. 
     
     
         7 . The method of  claim 6 , wherein the heating strip is electrically interconnected to the battery pack through a printed circuit board. 
     
     
         8 . The method of  claim 7 , further comprising the step of positioning the printed circuit board between the first non-conductive component and the second first non-conductive component, the first grouping of battery cells and the second grouping of battery cells being surrounded by the first non-conductive component and the second first non-conductive component and the printed circuit board being surrounded by the first non-conductive component and the second first non-conductive component. 
     
     
         9 . The method of  claim 1 , wherein the first grouping of battery cells and the second grouping of battery cells are surrounded by the first non-conductive component and the second first non-conductive component. 
     
     
         10 . The method of  claim 1 , wherein the heating device includes a heating strip and the method further comprising the steps of:
 electrically interconnecting the battery pack to a first portion of the heating device;   electrically interconnecting the first portion of the heating device to an electronic device through an electrical interface; and   electrically interconnecting the electronic device to a second portion of the heating device, the second portion including the heating strip.   
     
     
         11 . The method of  claim 1 , wherein the heating device includes a heating strip and the method further comprising the steps of:
 electrically interconnecting the battery pack to a first portion of the heating device;   electrically interconnecting the first portion of the heating device to an electronic device through an electrical interface; and   electrically interconnecting the electronic device to a second portion of the heating device through the electrical interface, the second portion including the heating strip.   
     
     
         12 . A battery assembly, comprising:
 a plurality of battery cells disposed adjacent one another and electrically interconnected to form a battery pack; a first grouping of cells of the plurality of battery cells being electrically interconnected in parallel, a second grouping of cells of the plurality of battery cells being electrically interconnected in parallel, the first grouping of cells and the second grouping of cells being electrically interconnected in series;   a heating device positioned to overlap at least a portion of the battery pack; and   a printed circuit board supporting and electrically connecting a plurality of electronic devices, the plurality of battery cells being electrically connected to the printed circuit board and the plurality of electronic devices applying electrical power from the battery pack to the heating device.   
     
     
         13 . The battery assembly of  claim 12 , further comprising a housing that surrounds the plurality of battery cells, the heating device, and the printed circuit board. 
     
     
         14 . The battery assembly of  claim 13 , wherein the housing includes a first non-conductive component and a second non-conductive component, the first non-conductive component and the second non-conductive component being disconnectable to allow access to the plurality of battery cells. 
     
     
         15 . The battery assembly of  claim 14 , further comprising a cable extending outside of the housing for connection to an electrical load. 
     
     
         16 . The battery assembly of  claim 12 , further comprising a plurality of jumper tabs electrically connecting the plurality of battery cells. 
     
     
         17 . The battery assembly of  claim 12 , wherein the first grouping of cells includes a first pair of battery cells, the second grouping of cells includes a second pair of battery cells. 
     
     
         18 . The battery assembly of  claim 12 , wherein the heating device includes a heating strip which is electrically connected to the plurality of battery cells through a connection to the printed circuit board. 
     
     
         19 . The battery assembly of  claim 12 , wherein the plurality of battery cells are electrically connected to the printed circuit board through a first portion of the heating device, a second portion of the heating device being electrically connected to the printed circuit board, the second portion of the heating device including a heating strip. 
     
     
         20 . The battery assembly of  claim 19 , wherein the first portion of the heating device and the second portion of the heating device are connected to the printed circuit board through a common electrical interface.