Patent Publication Number: US-2016226111-A1

Title: Thermal management systems and battery packs including the same

Description:
PRIORITY CLAIM 
     This application claims priority to U.S. Provisional Application 61/933,324, filed on Jan. 30, 2014, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     A system disclosed herein generally relates to managing a temperature of one or more substrates. More specifically. the system disclosed herein relates to a system to control thermal energy within a closed battery system. 
     2. Description of the Related Art 
     Batteries are devices that store electrical charge for a period of time. Some batteries are rechargeable when at least a portion of the electrical charge in the batteries is expended. The time during which battery life may be expended and recharged is known more commonly as “battery life.” Recent advances in battery technology have substantially lengthened battery life and the ability of the battery to maintain an electrical charge and recharge. However, these same advances have made batteries more susceptible to environmental changes such as battery temperature, humidity surrounding the battery, and many other factors. 
     These environmental changes are more pronounced when the changes are extreme. For example, extremely hot and extremely cold temperatures have a pronounced effect on the ability of a battery to maintain a charge over the useable life of the battery. These environmental effects are only further exacerbated when batteries are used in vehicles, for example, which may be subject to extremely hot and extremely cold temperatures. An automobile battery, for example, may be subject to very low temperatures in a cold weather climate and may be subject to very high temperatures in a warm weather climate. Similarly, other vehicles such as airplanes experience extreme cold in flight and relative warmth when on the ground. 
     Conventional systems fail, however, to maintain an optimal temperature in a battery exposed to extreme heat or extreme cold. In one embodiment, of this disclosure, a system to maintain an optimal temperature in a battery exposed to extreme heat or extreme cold is provided. 
     Conventional systems also fail to maintain a dry environment for a battery that is used outdoors. For example, vehicles are frequently exposed to humid or wet conditions. In another embodiment of this disclosure, a system to maintain a substantially dry battery environment is provided. 
     SUMMARY 
     Consistent with embodiments disclosed herein, a thermal management system is disclosed. The thermal management system includes a first heat exchanger, a second heat exchanger, and a thermoelectric pad. The thermoelectric pad is positioned such that it is in thermal contact with the first heat exchanger and the second heat exchanger. The thermoelectric pad may therefore be positioned between the first heat exchanger and the second heat exchanger. 
     In another implementation, a thermal management system is disclosed. The thermal management system includes a first heat exchanger disposed within a housing, a second heat exchanger disposed within the housing, a thermoelectric pad in thermal contact with the first heat exchanger and the second heat exchanger and positioned between the first heat exchanger and the second heat exchanger within the housing. The thermal management system also includes a substrate within the housing. The temperature of the housing is controlled by a thermal management system controller applying electric current to the thermoelectric pad. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and do not restrict the scope of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate several embodiments of the thermal management system disclosed herein and constitute a part of the specification. The illustrated embodiments are exemplary and do not limit the scope of the disclosure. 
         FIG. 1  illustrates a thermal management system for controlling the temperature of a closed system. 
         FIG. 2  illustrates a process for cooling a battery subjected to extreme heat to an optimal temperature using the thermal management system. 
         FIG. 3  illustrates a process for warming a battery subjected to extreme cold to an optimal temperature using the thermal management system. 
         FIG. 4  illustrates a process for removing humidity from a battery pack. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following description, for purposes of explanation and not limitation, specific techniques and embodiments are set forth, such as particular techniques and configurations. in order to provide a thorough understanding of the device disclosed herein. While the techniques and embodiments will primarily be described in context with the accompanying drawings, those skilled in the art will further appreciate that the techniques and embodiments may also be practiced in other similar devices. 
     Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. It is further noted that elements disclosed with respect to particular embodiments are not restricted to only those embodiments in which they are described. For example, an element described in reference to one embodiment or figure, may be alternatively included in another embodiment or figure regardless of whether or not those elements are shown or described in another embodiment or figure. In other words, elements in the figures may be interchangeable between various embodiments disclosed herein, whether or not shown in the accompanying figures. 
       FIG. 1  illustrates a thermal management system for controlling the temperature of a closed system  100 . In  FIG. 1 , closed system  100  is a battery pack containing a frame  105 , one or more batteries  110 , a battery controller  115 , all disposed within a housing  120 . The battery pack further includes one or more sensors  125  communicatively coupled to a thermal management system  130 . Thermal management system  130  includes a thermoelectric pad  135 , a first heat exchanger  140 , a second heat exchanger  145 , a thermal management system controller  150 , and a temperature receiver  155 . Also included in closed system  100  is a fan  160 , a thermal unit  165 , and a one way valve  170  disposed within housing  120 . 
     While  FIG. 1  shows one embodiment of closed system  100  that includes batteries, any substrate can be kept at an optimal temperature in a closed system, or alternately stated, a sealed environment, using thermal management system  130 . As used herein a substrate can be any material that is temperature sensitive or that can be made more efficient, useful, or cost effective through the application of heat or the removal of heat from the substrate. There are other embodiments in which aspects of this disclosure could be used in an open system, a system that does not contain a sealed environment or a system that is semi-sealed. However, aspects of this disclosure incorporated into an open system would be substantially less efficient in an open environment or a semi-sealed environment. In one embodiment, closed system  100  is substantially waterproof. For example, closed system  100  may be impenetrable to water at an IP-67 rating of the International Electrotechnical Commission standard 60529. 
     As shown in  FIG. 1 , one or more batteries  110  are disposed within frame  105  of housing  120  within closed system  100 . The number and size of batteries included within closed system  100  may vary based on the size limitations or power needs of a particular application. Thus, while four batteries are shown in  FIG. 1 , any number of batteries can be implemented within closed system  100 . Frame  105  and housing  120  of closed system  100  provide rigid support for one or more batteries  110  that are disposed therein. Frame  105  and housing  120  also provide rigid support for battery controller  115 . 
     Battery controller  115  may include a battery control module that provides an interface to a controller or sensors in a vehicle. In one simple example, battery controller  115  may interface with an electronic command module within a vehicle and provide information about one or more batteries  110  such as level of charge, voltage, amperage, and any other battery characteristic. Battery controller  115  may interface with a controller or sensors in a vehicle using a controller area network (“CAN”). The CAN is typically implemented in the vehicle by a CAN bus or TWI serial communication. However, battery controller  115  may be configured to communicate with the vehicle using any network connection, wired or wireless. 
       FIG. 1  further includes one or more sensors  125  that detect one or more environmental conditions within closed system  100 . For example, one or more sensors  125  may detect a temperature within closed system  100 , a temperature of the one or more batteries  110 , a humidity level within closed system  100 , a rate of cooling within closed system  100 , a rate of heating within closed system  100 , voltages, power consumption, and any other condition that may have an effect on the manner in which closed system  100  is heated or cooled. 
     Thermal management system  130  is disposed within closed system  100  to control and manipulate the environment within closed system  100 . Thermal management system  130  includes thermoelectric pad  135  which is disposed between first heat exchanger  140  and second heat exchanger  145 . First heat exchanger  140  is typically made of a metal or metal alloy conducive to the conduction of heat, examples of which include graphene, silver, copper, gold, aluminum, tungsten, zinc, nickel, iron, tin, and any alloy, amalgam, plating, or bond of these metals. First heat exchanger  140  includes one or more heat sink fins that increase the surface area, and therefore the thermal response, of first heat exchanger  140 . Second heat exchanger  145  may also be referred to as a water block. Second heat exchanger  145  may also be made of one of the previously discussed metal or metal alloys conducive to the conduction of heat and include a heat sink which may be implemented with heat sink fins or be arranged in the shape of a honeycomb within second heat exchanger  145 . A thermal liquid may be contained within second heat exchanger  145  and reside in thermal contact with the heat sink within second heat exchanger  145 . Thermal fluids include fluids that easily absorb and dissipate heat such as water, ethylene glycol, a mixture of ethylene glycol and water, methanol (methyl alcohol), propylene glycol, glycerol, or any other chemical compound with similar thermal properties. First heat exchanger  140  and second heat exchanger  145  are configured such that the respective abilities of first heat exchanger  140  and second heat exchanger  145  to conduct heat are substantially equal. In other words, in at least one embodiment, first heat exchanger  140  and second heat exchanger  145  may have substantially the same mass, substantially the same surface area, be made of substantially the same metal or metal alloy, and generally share the same ability to conduct, radiate, or dissipate heat. 
     Thermoelectric pad  135  provides for the conduction of heat between first heat exchanger  140  and second heat exchanger  145 . For example, thermoelectric pad  135  may include semiconductors that are disposed in a thermal substrate, such as, for example, a ceramic substrate. When an electrical current is applied to the semiconductors in thermoelectric pad  135 , a temperature differential occurs between each side of thermoelectric pad  135 . As electrically excited electrons flow from one side of thermoelectric pad  135  to the opposite side of thermoelectric pad  135 , one side of thermoelectric pad  135  cools while the opposite side of thermoelectric pad  135  warms. In this way, thermal management system controller  150  can conduct heat into closed system  100  and dissipate heat from closed system  100  merely by changing the direction of current flow through thermoelectric pad  135 , as will be discussed in more detail below. 
     Thermal management system  130  further includes thermal management system controller  150 . Thermal management system controller  150  can include a combination of one or more application programs and one or more hardware components configured to manipulate the internal temperature of closed system  100 . For example, application programs may include software modules, sequences of instructions, routines, data structures, display interfaces, and other types of structures that execute computer operations. Further, hardware components may include a combination of Central Processing Units (“CPUs”), buses, volatile and non-volatile memory devices, storage units, non-transitory computer-readable media, data processors, processing devices, control devices transmitters, receivers, antennas, transceivers, input devices, output devices, network interface devices, and other types of components that are apparent to those skilled in the art. Thermal management system controller  150  is configured to interface with temperature receiver  155 . Temperature receiver  155  receives temperature information for one or more of batteries  110  and communicates that temperature information to thermal management system controller  150 . Depending on the temperature information, thermal management system controller  150  may apply heat within closed system  100  or dissipate heat from closed system  100 . 
     Thermal management system controller  150  may control fan  160  that circulates heated or cooled air throughout closed system  100 . As the air circulates to cool closed system  100 , heat is conducted from first heat exchanger  140  to second heat exchanger  145  through thermoelectric pad  135  and to thermal unit  165  which contains a thermal fluid that absorbs heat from second heat exchanger  145  and dissipates it. As the air circulates to warm closed system  100 , heat within the thermal fluid of thermal unit  165  is conducted to second heat exchanger  145  and to first heat exchanger  140  through thermoelectric pad  135  which radiates heat into closed system  100 . 
     While several implementations of this system are possible, the system will now be described, in an exemplary and non-limiting fashion, in the context of a hybrid automobile, an automobile that is configured to operate using both power derived from a combustion engine and battery power together or independently. In this example, a hybrid automobile is parked in a hot environment. In this example, the hybrid automobile may be subjected to temperatures in excess of 100 degrees Fahrenheit during hot weather that is experienced by much of the United States during summer. Thus, the hot weather heats the car and all of the internal components, such as a hybrid automobile battery pack similar to closed system  100  shown in  FIG. 1 . As a result, the hybrid automobile battery pack experiences a temperature that is above the optimal temperature range for the battery pack, which has an adverse effect on the battery. In one embodiment, the optimal temperature range for the battery pack is between 35 and 80 degrees Fahrenheit and preferably within a range of 5-15 degrees Celsius (41-59 degrees Fahrenheit). 
     Continuing with the exemplary description of the automobile battery pack similar to closed system  100  shown in  FIG. 1 , when a driver turns the key in the hybrid automobile, thermal management system  130  detects, via thermal management system controller  150  and temperature receiver  155 , that the temperature of dosed system  100  exceeds an optimal temperature for battery operation and battery life. Thermal management system controller  150  then initiates a cooling sequence for closed system  100 . In this example, heat must be removed from closed system  100 . In order to remove the heat, electric current is provided to thermoelectric pad  135  in a direction that cools a first side of thermoelectric pad  135  that is positioned to be in thermal contact with first heat exchanger  140 . Heat from closed system  100  is absorbed through heat sink fins of first heat exchanger  140  and conducted to the cooled first side of thermoelectric pad  135 . This heat is conducted through thermoelectric pad  135  to a second side of thermoelectric pad  135  that is positioned to be in thermal contact with second heat exchanger  145 . In this manner, heat is radiated through the second side of thermoelectric pad  135  into second heat exchanger  145 . A thermal fluid within second heat exchanger  145  is pumped through second heat exchanger  145  and into thermal unit  165 . In this example, a radiator in the hybrid automobile may serve as thermal unit  165 . As the user drives the hybrid automobile, heat transferred into the thermal liquid through second heat exchanger  145  is radiated away from the hybrid automobile by the radiator of the hybrid automobile and rejected into the air flowing around the hybrid automobile. Fan  160  may be used to circulate air that has been cooled by the removal of heat through the heat sink fins of first heat exchanger  140  throughout closed system  100 . 
     In this manner, heat introduced into closed system  100  while the hybrid automobile is parked, may be conducted out of closed system  100  and away from the battery pack. Thermal management system controller  150  continuously receives temperature information for one or more batteries  110  via temperature receiver  155 . Once the temperature of one or more batteries  110  within closed system  100  is brought into an optimal range, thermal management system controller  150  adjusts the electric current level applied to thermoelectric pad  135  in order to maintain an optimal temperature environment within closed system  100 . 
     In another example, a hybrid automobile is parked in a cold environment. In this example, the hybrid automobile may be subjected to temperatures lower than 0 degrees Fahrenheit during cold weather that is experienced by much of the United States during winter. Thus, the cold weather cools the car and all of the internal components, such as a hybrid automobile battery pack that is similar to closed system  100  shown in  FIG. 1 . As a result, the hybrid automobile battery pack experiences a temperature that is below the optimal temperature range for the battery pack, which has an adverse effect on the battery. In one embodiment, the optimal temperature range for the battery pack is between 35 and 80 degrees Fahrenheit and preferably within a range of 5-15 degrees Celsius (41-59 degrees Fahrenheit). 
     Continuing with the exemplary description of the automobile battery pack which is similar to closed system  100  as shown in  FIG. 1 , when a driver turns a keyed ignition in the hybrid automobile, thermal management system  130  detects, via thermal management system controller  150  and temperature receiver  155 , that the temperature of closed system  100  is lower than an optimal temperature for battery operation and battery life. Thermal management system controller  150  then initiates a heating sequence for closed system  100 . In this example, heat must be introduced into closed system  100 . In order to introduce heat, current is provided to thermoelectric pad  135  that cools a second side of thermoelectric pad  135  that is positioned to be in thermal contact with second heat exchanger  145 . Thermal unit  165  may absorb heat into a thermal liquid contained within thermal unit  165 . In one embodiment, heat may be generated by a combustion engine operating within the hybrid automobile. The thermal liquid is pumped from thermal unit  165  through second heat exchanger  145 . As the second side of thermoelectric pad  135  cools, and because thermoelectric pad  135  is in thermal contact with second heat exchanger  145 , heat from the thermal liquid is conducted into second heat exchanger  145  and then to thermoelectric pad  135 . As heat is introduced to the second side of thermoelectric pad  135  which has been cooled by the applied electric current, heat is applied to the first side of thermoelectric pad  135  that is positioned in thermal contact with first heat exchanger  140 . First heat exchanger  140  is therefore heated by the heated first side of thermoelectric pad  135 . Heat is conducted into the heat sink fins of first heat exchanger  140  and there radiated into closed system  100  to warm one or more batteries  110 . Fan  160  may be used to circulate air that has been heated by heat radiating through the heat sink fins of first heat exchanger  140  throughout closed system  100 . 
     In this manner, heat may be introduced into dosed system  100  to heat one or more batteries  110  within closed system  100 . Thermal management system controller  150  continuously receives temperature information for one or more batteries  110  via temperature receiver  155 . Once the temperature of one or more batteries  110  within closed system  100  is brought into an optimal range, thermal management system controller  150  adjusts the electric current level applied to thermoelectric pad  135  in order to maintain an optimal temperature environment within closed system  100 . 
     Accordingly, dosed system  100  may be heated when necessary and cooled when necessary by alternating the direction of electric current flowing through thermoelectric pad  135 . First heat exchanger  140  and second heat exchanger  145  may then be used to remove heat from closed system  100  or introduce heat to closed system  100  depending on the temperature of one or more batteries  110 . In short, thermoelectric pad  135 , in combination with first heat exchanger  140  and second heat exchanger  145 , may both introduce heat to and remove heat from closed system  100 . Thus, the system may be thermally managed to maintain an optimal temperature for one or more batteries  110 . extending usable battery life. 
     In some environments, the climate may be so cold or so hot during portions of the year that batteries may be ruined by overheating or freezing. For example, in many parts of the United States many people connect their combustion engine automobiles to a 120 volt power source to keep their vehicles warm overnight. It is further conceivable that in some climates, it would be desirable to connect a vehicle to an external power source to keep the vehicle cool during the day. In these instances of extreme temperature, thermal management system  130  may be used to maintain an optimal temperature within closed system  100 , even when a vehicle is not moving. 
     Turning again to the example of a hybrid automobile, a vehicle in an extremely hot environment may be connected to an external power source such as AC power, either 120 volts AC or 220 volts AC, depending on the standard in a country in which the hybrid automobile is parked. As the hybrid automobile is parked, the hybrid automobile and the battery pack within the hybrid automobile is heated in the extremely hot environment. In this example, the exemplary battery pack within the hybrid automobile is similar to that of closed system  100 , shown in  FIG. 1 . Thermal management system  130  detects, via thermal management system controller  150  and temperature receiver  155 , that the temperature of one or more batteries  110  exceeds an optimal temperature for battery operation and battery life. Thermal management system controller  150  then initiates a cooling sequence for closed system  100 . In this example, heat must be removed from dosed system  100 . In order to remove the heat, electric current from the external power source is provided to thermal management system  130  because the car is not operating in this example. Thermal management system controller  150  applies electric current provided to thermal management system  130  to thermoelectric pad  135 . The electric current provided to thermoelectric pad  135  causes a first side of thermoelectric pad  135  that is positioned to be in thermal contact with first heat exchanger  140  to cool. Heat from closed system  100  is absorbed through heat sink fins on first heat exchanger  140  and conducted to the cooled first side of thermoelectric pad  135 . The heat is conducted through thermoelectric pad  135  to a second side of thermoelectric pad  135  that is positioned to be in thermal contact with second heat exchanger  145 . In this manner, heat is radiated through the second side of thermoelectric pad  135  into second heat exchanger  145 . A thermal fluid within second heat exchanger  145  may simply absorb and dissipate the heat in one embodiment. In another embodiment, electric power from the external power source may cause a pump to circulate thermal liquid through second heat exchanger  145  and thermal unit  165 . As the thermal liquid absorbs heat, the heat may be rejected into the air as the temperature of the liquid returns to an equilibrium temperature with the environment. In this manner, an optimal temperature may be maintained within closed system  100  for an extended period of time, even in a very hot climate. 
     In another example of a hybrid automobile, a vehicle in an extremely cold environment may be plugged in to an external power source such as AC power, either 120 volts AC or 220 volts AC, depending on the standard in a country in which the hybrid automobile is parked. As the hybrid automobile is parked, the hybrid automobile and the battery pack within the hybrid automobile is cooled in the extremely cold environment. In this example, the exemplary battery pack within the hybrid automobile is similar to that of closed system  100 , shown in  FIG. 1 . Thermal management system  130  detects, via thermal management system controller  150  and temperature receiver  155 , that the temperature of one or more batteries  110  is lower than an optimal temperature for battery operation and battery life. In response, thermal management system controller  150  initiates a heating sequence for dosed system  100 . In this example, heat must be introduced into closed system  100 . In order to introduce heat, electric current from the external power source is provided to thermal management system  130  because the car is not operating in this example. Thermal management system controller  150  applies electric current provided to thermal management system  130  to thermoelectric pad  135 . The electric current provided to thermoelectric pad  135  causes a first side of thermoelectric pad  135  that is positioned to be in thermal contact with first heat exchanger  140  to warm. Electric current provided to thermoelectric pad  135  such that the first side of thermoelectric pad  135  is heated causes first heat exchanger  140  to absorb heat and radiate that heat into closed system  100 . In this example, heat created by thermoelectric pad  135  is sufficient to warm first heat exchanger  140  because of the electric current provided by the external power source. While it is noted that a second side of thermoelectric pad  135  that positioned to be in thermal contact with second heat exchanger  145  will be cooled during this process, such cooling is not necessary for thermal management system  130  to provide heat to closed system  100 . Sufficient heat is provided to closed system  100  by thermoelectric pad  135  and first heat exchanger  140 . 
     Accordingly, thermal management system  130  may heat or cool closed system  100  depending on the external environment of closed system  100  and depending on whether or not an external power source is available. It is also advantageous to note that many hybrid automobiles are connected to an external power source to charge the batteries during periods of non-use. Thus, hybrid automobiles in particular are able to easily maintain an optimal temperature for a battery pack because of their ready access to an external power source. 
     Humidity inside closed system  100  can present a substantial problem. Any moisture in the air can be a proximate or distal cause of a battery shorting, corroding, or overheating. Therefore, in order to maintain the usable life for a battery, humidity must be closely controlled within closed system  100 . Thus, in one embodiment, one or more sensors  125  may be a humidity sensor to detect the humidity within closed system  100  and provide humidity information to thermal management system controller  150 . 
     As temperature within closed system  100  is adjusted by being exposed to an external environment or by thermal management system  130 , the humidity within closed system  100  can be increased. Accordingly, the rate of heating and cooling according to the foregoing description must be closely managed to prevent humidity from accumulating within closed system  100 . For example, if closed system  100  is cold and rapidly heated, condensation could form within closed system  100 , which could have a deleterious effect on one or more batteries  110  within closed system  100 . 
     Accordingly, in one embodiment, thermal management system  130  may be configured to slowly adjust the temperature of closed system  100  in order to prevent humidity from condensing and potentially causing damage to one or more batteries  110  within closed system  100 . Thermal management system controller  150  may therefore be configured to either selectively apply electric current to thermoelectric pad  135  or reduce the amount of electric current applied to thermoelectric pad  135  to slowly adjust the temperature of closed system  100 . However, if condensation is able to form, closed system  100  is provided with one way valve  170  that allows water from condensation to drain out of closed system  100 . Housing  120  may be configured to shed water by gravity to a low point within housing  120  where it may be easily drained through one way valve  170 . 
     In another embodiment, thermal management system  130  may be configured to balance the need to charge one or more batteries  110  within closed system  100  with the need for power to supply thermoelectric pad  135  with electric current. For example, thermal management system controller  150  may include a processor programmed to adjust the electric current supplied to thermoelectric pad  135  to charge the battery as fast as possible at an optimal temperature. In other words, thermal management system controller  150  may warm or cool one or more batteries  110  within closed system  100  more slowly in order to charge one or more batteries  110  faster. Thermal management system controller  150  may adjust the heating or cooling rate when a vehicle is in operation or when it is connected to an external power source. 
     Using the foregoing techniques, closed system  100  provides significant advantages in both battery life and battery efficiency. Such advances substantially improve available range in a hybrid automobile using battery power alone. Furthermore, the electrical draw to cool, heat, or maintain the internal temperature of closed system  100  is quite low, extending the operating range of a hybrid automobile to unprecedented levels. 
       FIG. 2  illustrates a process for cooling a battery subjected to extreme heat to an optimal temperature using the thermal management system. Process  200  begins at step  205 , a determination by a thermal management system controller, such as thermal management system controller  150  shown in  FIG. 1 , that one or more batteries, such as one or more batteries  110  shown in  FIG. 1  are hotter than an optimal temperature. In step  210 , thermal management system controller  150  adjusts electrical current applied to a thermoelectric pad, such as thermoelectric pad  135  shown in  FIG. 1 , to conduct heat from a first heat exchanger, such as first heat exchanger  140  shown in  FIG. 1 , to a second heat exchanger, such as second heat exchanger  145 , shown in  FIG. 1 . Thermal management system controller  150  monitors battery temperature by receiving information from a temperature receiver, such as temperature receiver  155  shown in  FIG. 1 , and one or more sensors, such as one or more sensors  125 , also shown in  FIG. 1 . At step  215 , thermal management system controller  150  determines whether or not the temperature within, for example, closed system  100 , is within an optimal range. If the temperature within closed system  100 , for example, is outside of an optimal range (Step  220 —No), thermal management system controller  150  continues conducting heat from first heat exchanger  140  to second heat exchanger  145  using the techniques described above and as shown in step  225 . Thermal management system controller  150  continues monitoring the temperature within closed system  100  (Step  215 ) and conducting heat out of closed system  100  (Step  225 ) until thermal management system controller  150  determines that the battery temperature is optimal (Step  230 —Yes). Once thermal management system controller  150  has determined that the temperature within closed system  100  is within an optimal range (Step  230 —Yes), thermal management system controller  150  may selectively apply electric current to thermoelectric pad  135  or substantially adjust electric current to thermoelectric pad  135  to maintain an optimal battery temperature in step  235 . 
       FIG. 3  illustrates a process for warming a battery subjected to extreme cold to an optimal temperature using the thermal management system. Process  300  begins at step  305 , a determination by a thermal management system controller, such as thermal management system controller  150  shown in  FIG. 1 , that one or more batteries, such as one or more batteries  110  shown in  FIG. 1  are colder than an optimal temperature. In step  310 , thermal management system controller  150  adjusts electrical current applied to a thermoelectric pad, such as thermoelectric pad  135  shown in  FIG. 1 , to conduct heat from a second heat exchanger, such as second heat exchanger  145  shown in  FIG. 1  to a first heat exchanger, such as first heat exchanger  140  shown in  FIG. 1 . Thermal management system controller  150  monitors battery temperature by receiving information from a temperature receiver, such as temperature receiver  155  shown in  FIG. 1 , and one or more sensors, such as one or more sensors  125  also shown in  FIG. 1 . At step  315 , thermal management system controller  150  determines whether or not the temperature within, for example, closed system  100 , is within an optimal range. If the temperature within closed system  100 , for example, is outside of an optimal range (Step  320 —No), thermal management system controller  150  continues conducting heat from second heat exchanger  145  to first heat exchanger  140  using the techniques described above and as shown in step  325 . Thermal management system controller  150  continues monitoring the temperature within closed system  100  (Step  315 ) and conducting heat into closed system  100  (Step  325 ) until thermal management system controller  150  determines, at step  315 , that the battery temperature is optimal (Step  330 —Yes). Once thermal management system controller  150  has determined that the temperature within closed system  100  is within an optimal range (Step  330 —Yes), thermal management system controller  150  may selectively apply electric current to thermoelectric pad  135  or substantially adjust electric current to thermoelectric pad  135  to maintain an optimal battery temperature in step  335 . 
       FIG. 4  illustrates a process for removing humidity from a battery pack. Process  400  begins at step  405 . a determination by a thermal management system controller, such as thermal management system controller  150  shown in  FIG. 1 , that humidity exists or exists at a certain level within a closed system, such as closed system  100  shown in  FIG. 1 . In step  410 , thermal management system controller  150  adjusts electrical current applied to a thermoelectric pad, such as thermoelectric pad  135  shown in  FIG. 1 , to conduct heat from a first heat exchanger, such as first heat exchanger  140  shown in  FIG. 1 , to a second heat exchanger, such as second heat exchanger  145 , shown in  FIG. 1 . Thermal management system controller  150  monitors humidity within closed system  100  by receiving humidity information from one or more sensors, such as one or more sensors  125 , also shown in  FIG. 1 . At step  415 , thermal management system controller  150  monitors battery temperature to determine whether or not ice has formed within closed system  100 . Ice forming within closed system  100  indicates that the humidity within closed system  100  has transformed from an airborne state to a frozen state. If ice has not formed within closed system  100  (Step  420 —No), thermal management system controller  150  continues conducting heat from first heat exchanger  140  to second heat exchanger  145  as shown in step  425 . Thermal management system controller  150  continues monitoring the temperature within closed system  100  (step  415 ) and conducting heat out of closed system  100  (Step  425 ) until thermal management system controller  150  determines that ice has formed within closed system  100 . Once thermal management system controller  150  has determined that ice has formed within closed system  100  (Step  430 —Yes), thermal management system controller  150  adjusts the electric current (i.e., reverses the direction of the flow of electric current) to thermoelectric pad  135  to conduct heat from second heat exchanger  145  to first heat exchanger  140 , as shown in step  435 . Heat is reintroduced into closed system  100  in a manner that converts the ice to water without reintroducing it to the air. In step  440 , the ice melts as heat is applied to first heat exchanger  140  through thermoelectric pad  135 . As the ice melts, it is converted to water which is shed through a one way valve, such as one way valve  170  and drained out of closed system  100  in step  445 . Humidity is therefore removed from within closed system  100 . 
     In one embodiment, multiple thermoelectric pads, such as one or more of thermoelectric pads  135  shown in  FIG. 1 , may be implemented in a closed system, such as closed system  100 . Multiple thermoelectric pads may provide additional power for heating and cooling closed system  100  as needed for a particular application. Electric current may be selectively applied to each thermoelectric pad such that a hot side of one thermoelectric pad is positioned in thermal contact with a cold side of another thermoelectric pad. Alternatively, multiple first heat exchangers, such as one or more of first heat exchanger  140  shown in  FIG. 1  and multiple second heat exchangers, such as one or more of second heat exchanger  145  shown in  FIG. 1  may be implemented with multiple thermoelectric pads as may suit a particular application. For example, in some implementations, such as airplanes or spacecraft, the power of multiple thermoelectric pads may be necessary to counteract the extreme temperatures of high altitude or outer space. 
     The foregoing description has been presented for purposes of illustration. It is not exhaustive and does not limit the invention to the precise forms or embodiments disclosed. Modifications and adaptations will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments. For example, components described herein may be removed and other components added without departing from the scope or spirit of the embodiments disclosed herein or the appended claims. 
     Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.