NOVELTY - A battery pack comprises a porous medium (20) positioned in a case; batteries (18) held by the porous medium; terminals for accessing power from the batteries, where terminals are accessible from outside of the case; and a flame retardant in pores (22) of the porous medium.    USE - As a battery pack useful in electrical circuits, digital electrical circuits, processors, microprocessors, digital signal processors (DSPs), computers, microcomputers, application specific integrated circuits (ASICs), and/or discrete electrical components. The electronics can include switches, resistors, capacitors, electrical lines, and other electrical connections. The battery pack is useful in vehicles, such as cars, truck and golf-carts.    ADVANTAGE - The combination of the high thermal conductivity and a low electrical conductivity enhances the ability of the porous medium to absorb energy from the batteries. The ability of the porous medium to absorb the energy can reduce the failure of the batteries. The flame retardants can stop or reduce battery volatility by several different mechanisms. The flame retardant can have a high heat capacity in its liquid phase to absorb heat from the battery and slow down the reaction associated with thermal runaway. As a result, the flame retardants can have a boiling point higher than the runaway temperature of the battery to address the reactions after the runaway triggering reaction. The flame retardant suppresses volatility of the batteries. The presence of the flame retardant in the pores further reduces of failure of the batteries. The use of multiple batteries in the battery pack allows the battery pack to occupy a large number of shape configurations by re-arranging the batteries into cases having different shapes. The shape of the porous media and the positions of the batteries relative to one another can be altered so the batteries fit into a case with a different shape. The use of multiple batteries allows collection of cases that each has a different shape but has the same number of batteries and accordingly provides the same voltage and/or capacity. As a result, the battery pack is suitable for positioning in the unusually shaped locations that are available in increasingly smaller automobiles.    DETAILED DESCRIPTION - A battery pack comprises a porous medium (20) positioned in a case; batteries (18) held by the porous medium; terminals for accessing power from the batteries, where terminals are accessible from outside of the case; and a flame retardant in pores (22) of the porous medium. The batteries are connected in several parallel and series groups. The porous medium has a solid-liquid phase transition at a temperature of less than a runaway temperature of the batteries. The porous medium has a thermal conductivity greater than 1 W/mk and a melting point of less than 350 degrees C. The flame retardant is included in a liquid having an electrical conductivity less than 10-5 Scm. The porous medium has a porosity of greater than 5%. The flame retardant has a boiling point of 80-160 degrees C at 1 atmosphere (atm.). The flame retardant has a heat of vaporization lower than 150 J/g at boiling point and 1 atm.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective view of the case with cover detached from the receptacle and batteries positioned in the case.    Cover (12)    Receptacle (14)    Batteries (18)    Porous medium (20)    Pores (22)