Abstract:
A battery pack for thermal conduction of heat from a battery cell to a portable computer system is described. The battery pack comprises a housing, a battery cell within the housing, at least one electrode, and a thermal transfer contact separate from the at least one electrode. The thermal transfer extends through the housing and transfers heat from the battery cell to external of the battery pack.

Description:
BACKGROUND 
     Battery packs provide power to portable computer systems, e.g., laptops, notebooks, palmtops, etc. Battery packs may be used to provide power during periods when main power, such as alternating current (AC) power, may be unavailable. In many instances, battery packs are retained within the connected computer system, e.g., inserted into a cavity in the portable computer system. 
     During and after use, e.g., charging and discharging, battery packs generate heat which may decrease performance and reliability of the battery packs. 
       FIG. 1  depicts a side section schematic diagram of a portion of a portable computer system  100  comprising a computer housing  101  forming a cavity  102  for receiving a battery pack  104 . Battery pack  104  comprises a housing  106 , e.g., a plastic shell, enclosing a battery cell  108 , e.g., an electrochemical cell. For orientation purposes, an upper surface of housing  106  is the portion closest to the top of the page and a lower surface is the portion closest to the bottom of the page. Heat generated by battery pack  104  generally rises from the bottom of the page toward the top of the page. Battery cell  108  is positioned in battery pack  104  and prevented from moving within the pack through the application of four positioning members  110 , e.g., glue or silicone portions, between the cell and the pack. A pair of electrodes  112  extend from battery cell  108  to an outer surface of housing  106  in order to contact a pair of contacts  114  in cavity  102  to transfer an electric charge to/from the battery cell. An air gap  116  separates battery cell  108  from housing  106  and acts as an insulator to retain heat within housing  106 . An additional air gap is formed between cavity  102  walls and battery pack  104  to facilitate user removal. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein: 
         FIG. 1  is a side section schematic diagram of a battery pack positioned in a computer; 
         FIG. 2  is a side section schematic diagram of a battery pack according to an embodiment positioned in a computer; 
         FIG. 3  is a side section schematic diagram of a battery pack according to another embodiment positioned in a computer; 
         FIG. 4  is a side section schematic diagram of a battery pack according to another embodiment positioned in a computer; 
         FIG. 5  is a side section schematic diagram of a battery pack according to another embodiment positioned in a computer; and 
         FIG. 6  is a side section schematic diagram of a battery pack according to another embodiment positioned in a computer. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  depicts a side section schematic diagram of portable computer system  100  and a battery pack  200  according to an embodiment positioned within cavity  102  of the portable computer system. Battery pack  200  comprises a housing  202  (battery housing) enclosing a battery cell  204 , e.g., an electrochemical storage cell and a pair of optional positioning members  206  (dashed line), e.g., glue or silicone portions, between a lower surface of battery cell  204  and an inner surface of housing  202  maintain the battery cell in position within the housing. Battery pack  200  further comprises a pair of electrodes  208  extending from battery cell  204  to an outer surface of housing  202  in order to contact the pair of contacts  114  in cavity  102  to transfer an electric charge to/from the battery cell. 
     Battery pack  200  further comprises a pair of thermal transfer contacts  210  extending from battery cell  204  to beyond housing  202  in order to contact a surface of cavity  102  of the portable computer system  100 . Thermal transfer contacts  210  comprise a thermal transfer material, e.g., a metal, a plastic, etc. Thermal transfer contacts  210  conduct heat from battery cell  204  through housing  202  to portable computer system  100 . Thermal transfer contacts  210  provide a pathway for heat to transfer away from battery cell  204  because the contacts provide a lower resistance conductive path for the heat in comparison to housing  202  and the air gap between the battery cell and the battery housing. 
     In some embodiments, a single thermal transfer contact may be used in place of the pair of thermal transfer contacts  210 . In some embodiments, more than two thermal transfer contacts may be used in place of the pair of thermal transfer contacts  210 . 
     As depicted in  FIG. 2 , thermal transfer contacts  210  extend toward an upper surface of battery pack  202  to contact a lower surface of portable computer system  100 . In this manner, the surface area of portable computer system  100  may be used to dissipate the heat generated by battery cell  204 . That is, the heat of battery cell  204  is transferred to the body of portable computer system  100 . 
     In some embodiments, thermal transfer contacts  210  may extend through housing  202  horizontally at one or more sides of battery pack  200  to contact a surface of cavity  102 . 
     In some embodiments, one set of thermal transfer contacts  210  extend horizontally and another set of thermal transfer contacts  210  extend vertically to contact cavity  102 . 
       FIG. 3  depicts another embodiment of battery pack  200  in which a thermally conductive substance, e.g., a thermal paste  300 , is applied between an outer face of battery cell  204  and an inner face of housing  202 . Thermal paste  300  conducts heat from battery cell  204  to battery pack housing  202 . 
     As depicted, thermal paste  300  is applied to an upper and lower face of battery cell  204 . In some embodiments, thermal paste  300  may be applied to an upper face of battery cell  204  and direct contact may be made between the lower face of battery cell  204  and inner face of housing  202 . In at least one other embodiment, thermal paste  300  may be applied to an upper face of battery cell  204  and at least one positioning member is placed between the lower face of the battery cell and the inner face of housing  202 . In at least one other embodiment, thermal paste  300  may be applied to at least one side face of battery cell  204  to contact housing  202 . In at least one further embodiment, thermal paste  300  may be applied to an upper face of battery cell  204  and an air gap, similar to air gap  116  ( FIG. 1 ) may be maintained between battery cell  204  and housing  202  for the remainder of the exterior of the battery cell lacking thermal paste. 
     In the  FIG. 3  embodiment, battery pack  200  further comprises a pair of thermal transfer contacts  302 , similar to thermal transfer contacts  210  ( FIG. 2 ), in contact with thermal paste  300  and extending through housing  202  to contact portable computer system  100 , e.g., by contact with a surface of cavity  102 . In this manner, thermal paste  300  transfers heat from a larger surface area of battery cell  204  to thermal transfer contacts  302 . In some embodiments, thermal paste  300  may serve to position battery cell  204  within housing  202 . In some embodiments, thermal transfer contacts  210  extend partially into thermal paste  300 . In some embodiments, thermal transfer contacts  210  extend through thermal paste  300  to contact with the surface of battery cell  204 . 
       FIG. 4  depicts another embodiment of battery pack  200  in which thermal paste  300  is applied to an upper and lower face of battery cell  204 . The battery pack further comprises a pair of thermal transfer contacts  400  to transfer heat from battery cell  204  via thermal paste  300  to a pair of compressible contacts  402  connected to a surface of cavity  102  of the portable computer system  100 . Compressible contacts  402  comprise a thermally conductive material to transfer heat from thermal transfer contacts  400  to portable computer system  100 . In some embodiments, compressible contacts  402  may be a leaf spring, coil spring, spiral spring, cantilever spring, or other type of compressible device for contacting the thermal transfer contacts. Changes in positioning of battery pack  200  within cavity  102  may be accounted for by the use of compressible contacts  402 . In some embodiments, compressible contacts  402  are molded/formed as a part of computer housing  101 , e.g., springs may be formed as a part of the computer housing. In some embodiments, compressible contacts  402  comprise metal springs riveted to computer housing  101 . 
     In some embodiments, a single compressible contact may be used in place of a pair of compressible contacts. In some embodiments, more than two compressible contacts may be used. In some embodiments, there may be more compressible contacts than thermal transfer contacts in battery pack  200 . In some embodiments, there may be more thermal transfer contacts in battery pack  200  than compressible contacts  402  in cavity  102 . 
     Compressible contacts  402  are positioned to align with a corresponding number of thermal transfer contacts  400  in battery pack  200 . In some embodiments, compressible contacts  402  may be positioned on the side surfaces of cavity  102 . 
       FIG. 5  depicts another embodiment of battery pack  200  in which thermal paste  300  is applied to an upper and lower face of battery cell  204  and the pair of thermal transfer contacts  400  extending through housing  202  to transfer heat from the battery cell via the thermal paste. A pair of compressible contacts  500  are connected to a corresponding thermal transfer contact  400  on the outer surface of housing  202 . Compressible contacts  500  comprise a thermally conductive material to transfer heat from thermal transfer contacts  400  to portable computer system  100 . In some embodiments, compressible contacts  500  may be a leaf spring, coil spring, spiral spring, cantilever spring, or other type of compressible device for contacting the portable computer system  100 . 
     In some embodiments, compressible contact  500  may be connected to housing  202  and arranged to contact an upper surface of thermal transfer contact  400 . 
       FIG. 6  depicts another embodiment of battery pack  200  in which portable computer system  100  further comprises a conducting strip  600  positioned to contact compressible contacts  500 . In some embodiments, conducting strip  600  may be formed as part of the surface of cavity  102 . Conducting strip  600  transfers heat from battery pack  200  via compressible contacts  500  to a display  602  connected to portable computer system  100 . Display  602  comprises a thermally conductive material in order to radiate heat transferred from battery pack  200 .