Patent Application
20060110657
Batteries are used extensively to maintain power when the utility power is down. Standby power and Uninterruptible Power Supplies applications include central telephone offices, wire-line remote terminals, fiber-optic terminals, cable-television power, and cellular telephone repeaters. Lead acid batteries of two types, Valve Regulated Lead Acid (VRLA) and flooded-cell, dominate these applications. The flooded-cell, lead-acid batteries used in central telephone offices have been remarkably successful; life of 20 years has not been unusual. To achieve these lifetimes, flooded-cell, batteries are housed in air-conditioned rooms where the temperature is maintained in the range of 75° F. (Fahrenheit), the specific gravity of the electrolyte in each battery is monitored and corrected as necessary, terminal connections are checked and maintained, voltages for charge and float are checked and adjusted, discharge characteristics are tested and evaluated, and, most important of all, water is replaced in the cells as required.
The growth in business in industrial parks and the shift of residences to the suburbs outside of the city required high capacity communication networks to be built to serve these new locations. This change resulted in communication switches being distributed throughout the network in unmanned facilities; often metal cabinets alongside the road. The concept of standby powering used in central offices was extended to these locations that were distributed throughout the neighborhoods. However, the flooded-cell batteries could not be used in these applications because of their maintenance requirements and because of the potential for pollution from a battery spill. A new type of lead-acid battery was developed that did not require the replacement of water and in which the electrolyte was held in suspension so that it could not be spilled in the case of an accident. This battery is called the Valve Regulated Lead Acid Battery. There are two types of VRLA batteries, the Gel Cell and the Absorbent Glass Matt. In the first, the electrolyte is in a gelled state. In the second, the electrolyte is absorbed in tiny holes in layers of glass matt. In both types, the electrolyte is “captured” so that it cannot leak if the battery is tipped or punctured. In terms of attempting to protect batteries from heat and cold, the prior art includes placing a battery or multiple batteries into thermally controlled and/or insulated boxes.
Most of the batteries in these distributed applications are in metal cabinets that are exposed to high and low temperatures. Where exposed to high temperatures, even in a thermally insulated box, though to a lesser extent, these batteries have had useful lives much shorter than their design lives, and when exposed to low temperatures, the capacity of the battery is reduced.
The present invention resolves the foregoing limitations and concerns with the batteries recited above as well as other batteries displaying these deficiencies while providing still further advantages.
In accordance with one aspect of the present disclosure, a battery including a housing and at least one terminal extending out of the housing is described. A thermally conductive mechanism is positioned outside the housing but in sufficiently close proximity to the terminal and configured in a way which defines a thermally conductive path outside the housing from a point proximate the terminal to a point further from the terminal. In one embodiment of this battery assembly, the thermally conductive mechanism is comprised of at least one thermally conductive bracket that may be electrically isolated from one or both battery terminals. In this same embodiment a heat sink may be positioned in sufficiently close proximity to the further point defined by the thermally conductive path so as to receive heat reaching the last-mentioned point as it passes from the terminal along the path. Again, in this particular embodiment, a heat pump can be provided to cooperate with the thermally conductive mechanism and the heat sink for aiding in the movement of heat from the terminal to the heat sink. Moreover, a heater can be positioned for heating the battery. Further, an arrangement of vacuum insulated panels can define a thermally isolated interior which receives the battery in a way which provides for forming an external electrical connection with the battery terminals. In one feature, the battery terminals and at least a portion of the thermally conductive bracket is within the thermally isolated interior.
In accordance with another aspect of the present disclosure, there is described an overall battery assembly which includes a battery having a housing and an arrangement of components mounted with and carried by the battery housing. These components include a cooling mechanism and a heating mechanism configured so as to keep the temperature within the battery housing within a desired temperature range. In one embodiment, the cooling mechanism includes a thermally conductive bracket, a heat sink and a heat pump and the heating mechanism includes a heater.
In accordance with another aspect of the present disclosure, there is described a backup battery assembly for use in an overall uninterruptible power system which includes a primary power supply for powering a primary load. The backup battery assembly itself includes a backup battery (i) adapted for connection with the primary power supply so that the primary power supply is able to recharge the backup battery and (ii) adapted for connection with the primary load so that the backup battery is able to power the primary load when the primary power supply is unable to do so. The assembly also includes an arrangement connected with and powered by the backup battery for causing heat to move away from the battery whereby to cool down the battery, the arrangement including a sensor for sensing when the battery is being used to power the primary load and circuitry for insuring that the arrangement does not use power from the battery to cause heat to move away from the battery when the battery is being used to power the primary load. In one embodiment, the arrangement includes circuitry for insuring that the arrangement causes heat to move away from the battery at least when the battery is first recharged after being used to power the primary load, whereby to cool down the battery during recharging.
In accordance with still another aspect of the present disclosure, there is described an uninterruptible power system for powering a primary load. This system includes a primary power supply for powering the primary load and a backup battery (i) connected with the primary power supply so that the primary power supply is able to recharge the backup battery and (ii) connected with the primary load so that the backup battery is able to power the primary load when the primary power supply is unable to do so. An arrangement is connected with and powered by the backup battery for causing heat to move away from the battery for cooling down the battery and this arrangement includes a sensor for sensing when the battery is being used to power the primary load and circuitry for insuring that the arrangement does not use power from the battery to cause heat to move away from the battery when the battery is being used to power the primary load. Again, in one embodiment, the arrangement includes circuitry for insuring that the arrangement causes heat to move away from the battery at least when the battery is first recharged after being used to power the primary load so as to cool down the battery during recharging.
In each of these aspects of the present disclosure, the battery assembly according to one embodiment thereof is integrated to the extent that the various components making it up, for example, the thermally conductive bracket, the heat sink and the heat pump and heater are all mounted with the battery itself such that the overall assembly is portable.
The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein including alternatives, modifications and equivalents, as defined within the scope of the appended claims. It is noted that the drawings are not to scale and are diagrammatic in nature in a way that is thought to best illustrate features of interest. Further, like reference numbers are applied to like components, whenever practical, throughout the present disclosure. Descriptive terminology has been adopted for purposes of enhancing the reader's understanding, with respect to the various views provided in the figures, and is in no way intended as being limiting.
As will become apparent hereinafter, the advantages that are provided by the various embodiments of the present invention include, but are not limited to:
1. Improving the life and reliability of VRLA batteries by providing practical, cost effective, self-contained, temperature-control configurations for these batteries.
2. Implementing temperature control arrangements so that:
Features used to implement the invention include:
These features, when used as described herein, provide temperature control of a battery with a minimum volume of insulation, provide an integral temperature controller requiring no change in the basic operational paradigms, and provide effective temperature control of the battery to achieve improvements in reliability and life. Conduction of heat through the terminals and the coupling of the terminals thermally are considered to provide sweeping advantages over the prior art. In this way, the temperature of the grid structure of VRLA batteries is well controlled with a minimum of thermal gradients. The use of one or both terminals should be based on certain factors which are described in detail below.
Using the features set forth above, as described, a battery is provided with its own self-contained refrigerator. Similar to home refrigerators, the volume used to insulate the refrigerated space must be minimized so that usable volume is maximized. In addition, the insulation must have high thermal resistance to minimize the heat that must be removed from the battery. Heat conducted into the battery must be minimized because the more heat that has to be removed, the higher the power required to pump the heat. Ideally, one wants the power used to pump heat to approach zero, since any power used to pump the heat is power that is not available for the intended application. The VIPCell™ battery concept addresses these design goals by using Vacuum Insulated Panels as the insulation material. Next to vacuum itself, vacuum insulated panels have the highest levels of thermal resistance per unit of thickness. By using an adequate thickness of this material, the heat flow is reduced such that the power required to pump excess heat, whereby to keep the battery cool (or warm, in some instances), is acceptable.
As a further aspect of the invention, it is recognized that, in most applications, cooling of the battery can be shut-off when the battery is supplying power. This is possible for two reasons. First, because the time that the battery will be supplying power is short compared to its life, it is permissible for the battery temperature to rise during that relatively short time without it having a significant affect upon its life. Second, since the thermal time constant for the insulated battery, as taught herein, is very long, often on the order of one to two days, the battery temperature will only rise by a relatively small amount during the time that it is providing power; usually only hours or fractions of hours and, in any case, usually much shorter than a day.
Another benefit of integral temperature control, as taught herein, is achieved in that the life and reliability of a battery will not only be improved when used as an individual battery but will also be improved when used in series and parallel combinations, as is the case for most standby power and UPS (Uninterruptible Power System/Supply) applications. In these combinations, batteries are subject to thermal runaway during charging. This results, for example, from one of the batteries in a series string having a higher series resistance and therefore a higher voltage than the other batteries in the string. Since all of the batteries have the same current flowing through the string, the battery having higher resistance will have more power dissipated in it. All other effects being equal on the batteries, that battery will get hotter than the other batteries in the string. With increasing temperature, the series resistance of the hot battery will increase which will cause the battery to dissipate more power and get still hotter. If this condition is serious enough, it can lead to explosion. If less serious, the hot battery will be damaged over time and will lead to a shortened life for itself but also, unfortunately, for its companions. Integral temperature control prevents this problem in many battery applications, for example, by maintaining all of the batteries at a set temperature with small variance even with differences in dissipated power. Managing the temperature differences between batteries in strings can significantly reduce a known cause of shortened life and reduced reliability.
Thickness of insulation, levels of power to pump the heat, the amount of heat, the size of the heat sink all vary by battery size and power delivered. Tradeoffs between insulation thickness, size of heat sink, the use of fans, and the size of the thermoelectric cooler can be made to meet the requirements for specific types of applications. For example, batteries used to provide back-up power when utility power is not available can use utility power to pump the heat for most of the operating time since utility power is present most of the time. To minimize acquisition cost and maximize usable volume, the appropriate design trade-off is in the direction of lower amounts of insulation and higher amounts of power to pump the heat. In contrast, batteries used in conjunction with solar power would want to minimize the amount of heat to be pumped by increasing the insulation thickness and thereby reducing the “parasitic” power to pump heat. This is because reductions in total power required serve to reduce the size of the solar array. The concept of using Vacuum Insulated Panels to make integral temperature control of individual batteries feasible is considered to be applicable to any battery chemistry, so long as the contemplated benefits are achieved. For example, Lithium batteries, that prefer to operate at 40° C., can be insulated with Vacuum Insulated Panels to reduce the amount of heat required to keep them warm. Since lithium batteries need to be kept warm for both charge and discharge, minimization of the power required is highly desirable.
Still referring to
In summarizing the various embodiments of battery assembly 99 thus far described, a battery 100 including a housing 101 and at least one terminal 4 extending out of the housing is described. A thermally conductive mechanism, for example bracket 2, is positioned outside the housing but in sufficiently close proximity to the terminal and configured in a way which defines a thermally conductive path outside the housing from a point proximate the terminal to a point further from the terminal. In one embodiment of battery assembly 99, the thermally conductive mechanism is a comprised of one or more thermally conductive brackets (that is, one or more brackets 2). In this same embodiment, heat sink 1 is positioned in sufficiently close proximity to the further point defined by the thermally conductive path so as to receive heat reaching the last-mentioned point as it passes from the terminal along the path. Again, in this particular embodiment, a heat pump, for example thermoelectric cooler 3, is provided to cooperate with the thermally conductive mechanism and the heat sink for aiding in the movement of heat from the terminal to the heat sink. Moreover, heater 104 is positioned for heating the battery through housing 101. Further, the housing can be encased by an arrangement of vacuum insulated panels 7 in a way which exposes the terminal to the ambient surroundings.
The temperature control methodology, referred to above, can be non-linear, linear, or pulse width modulation. Nominally, temperature is controlled with the thermoelectric cooler 3 and heater 104 to keep the battery between 20° C. and 25° C., for a VRLA, when the temperature of the environment is hotter than 25° C. and between 0° C. and 10° C. when colder than 0° C. If a Digital Signal Processor, or equivalent, is used as the control section 110, then an optional battery current sensor, generally indicated at 112 in
Indeed, regardless of the details of control section 110, it can be configured with a current sensor 112 in accordance with the present invention (i) to sense when battery 100 is and is not discharging (delivering power to the primary load) and, during that time, (ii) to disconnect (or otherwise de-activate) the thermoelectric cooler from the battery so the battery does not have to deliver power to both the primary load and the thermoelectric cooler. Moreover, control section 110, in accordance with this particular embodiment, may be provided with circuitry to automatically reconnect (or re-activate) the thermoelectric cooler as soon as sensor 112 senses that the battery is no longer discharging. At that time, more than likely, primary power source 116 will be charging the battery and this charging operation is made more efficient if the battery is cooler rather than hotter. For that reason and the fact that the battery will have more than likely heated up during the discharge (power delivery) cycle (with the cooler de-activated), it is important to re-activate the cooler.
The overall battery assembly 99 described immediately above in conjunction with
Having described the present invention in detail above, it will be appreciated that the concepts herein are thought to resolve problems that have never been addressed in an effective way. The associated benefits should not be taken lightly, particularly from an environmental standpoint. That is, considering the vast and ever increasing number of VRLA batteries in backup power use, the application of the present invention will provide a battery that will reach its design life under hostile environmental conditions, whereas a prior art battery that is subjected to these conditions may have a life that is one-half or less than its rated design life. Thus, there can be a significant reduction, for example, in lead pollution resulting from manufacturing activities.
Attention is now directed to
Moreover, it is to be understood that the various individual components making up the overall uninterruptible power system generally and the battery assembly in particular are by themselves readily providable by those with ordinary skill in the art in view of the teachings herein. Those components include, for example, the thermally conductive bracket 2, the thermoelectric cooler 3, the heat sink 1, the vacuum insulated panels 7 and the circuitry associated with the block diagrams of
Although each of the aforedescribed physical embodiments have been illustrated with various components having particular respective orientations, it should be understood that the present invention may take on a variety of specific configurations with the various components being located in a wide variety of positions and mutual orientations. Furthermore, the methods described herein may be modified in an unlimited number of ways, for example, by reordering the various sequences of which they are made up. Therefore, the present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.
The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/628,366, filed on Nov. 15, 2004, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60628366 | Nov 2004 | US |
