Abstract:
A device for monitoring the environment of a battery. The device takes the form of a generally flat wafer-like substrate having openings therein for receiving the posts of the battery. The device is arranged so that it is sandwiched between the battery and its connector when the female receptacles of the connector are mated with the posts. Circuitry on the wafer contains a memory for recording information about the battery characteristics. This information can be read from the memory to provide knowledge about battery operating time, number of charge/discharge cycles, number and severity of deep-discharge cycles, total time spent in deep discharge, temperature fluctuations and G-loads applied to the battery. By taking advantage of the existing space between mated battery connectors, no additional mounting hardware or battery modifications are required.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 07/998,354, filed Dec. 30, 1992 (abandoned), which was a continuation in part of Ser. No. 07/938,111 filed Aug. 31, 1992, now U.S. Pat. No. 5,290,191, which was a continuation in part of Ser. No. 07/895,148, filed Jun. 5, 1992, now U.S. Pat. No. 5,181,859, which was a continuation of Ser. No. 07/694,262, filed Apr. 29, 1991 (abandoned). 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to sensors and, more particularly, to a device for sensing characteristics of a battery. 
     2. Discussion 
     In many applications it would be desirable to sense the characteristics of a battery. This is especially true with batteries that are used to power equipment where it is essential that a reliable source of power is consistently maintained. For example, batteries used on many systems by the Department of Defense are being replaced with the latest technology high-reliability, maintenance-free batteries (HRMFB). While improvements in reliability and performance are expected from these new batteries, reliability engineers need to understand and quantify the actual gains to establish optimum maintenance intervals and number of required spares. Basing these decisions on real-life performance data, as opposed to educated guesses, will yield significant cost savings by reducing the work load on battery maintenance and avoiding having too many or too few spare batteries on the shelves. The devices may also provide a means for determining whether a failed battery was within warranty limits. 
     It is known that the environment to which the battery is exposed can shorten or prolong expected life. Factors having the greatest effect on battery reliability include operating time, number of charge/discharge cycles, number and severity (i.e. magnitude depth) of deep-discharge cycles, temperature fluctuations, and G-loads. Sensors are currently available to measure and record these parameters, but most of them require costly retrofit or redesign of the battery structure to enable the sensor to be installed. In most cases it is neither practical nor cost effective to hard-wire a sensor inside an aircraft battery. Because of these drawbacks, data on large numbers of batteries under real operating conditions are difficult to obtain. 
     The present invention is directed to solving one or more of these problems. 
     SUMMARY OF THE INVENTION 
     In accordance with the teachings of the present invention, a device is provided for obtaining information about battery characteristics, yet is easy to install. The device takes advantage of the existing space between the mated battery and its connector and non-intrusively monitors and records the battery environment. No additional mounting hardware or battery modifications are required. Preferably, the unit is entirely self-contained and is capable of recording environmental data onto a non-volatile memory. 
     In the preferred embodiment, the device takes the form of a generally flat wafer-like substrate having first and second openings therein for receiving the positive and negative posts of the battery. Circuitry carried by the substrate is used to detect characteristics of the battery. Conductive means are utilized to make electrical connection between the posts and the circuitry. The device is constructed so that it lies essentially parallel to the battery surface, with the posts extending through the openings in the wafer and making contact with the conductive means. 
     In use, the device is sandwiched between the surface of the battery and the connector when the female receptacles therein are mated with the posts to supply power to electrical apparatus during normal operating conditions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to those skilled in the art after reading the following specification and by reference to the drawings in which: 
     FIG. 1 is an exploded perspective view of the operable arrangement between the battery, connector and the battery sensing device of this invention; 
     FIG. 2 is a cross-sectional view showing the battery sensing device sandwiched between the connector and battery during normal operation; 
     FIG. 3 is an enlarged plan view of the preferred embodiment of the battery sensing device; 
     FIG. 4 is a schematic block diagram of the circuitry for sensing the battery characteristics; and 
     FIG. 5 is a view showing a hand-held controller reading information from the battery sensing device, with the controller being also coupled to a computer. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate the battery sensor wafer device 10 of the present invention, a battery 12 and a battery connector 14. A positive battery post 16 and a negative battery post 18 extend from a major surface 20 of the battery 12. The present invention can be used with a wide variety of different battery designs. However, it finds particular utility for use with high-reliability, maintenance-free batteries (HRMFB) which are used on aircraft such as B-52&#39;s. In these applications it is of utmost importance that the batteries consistently provide the necessary power for the aircraft electronic systems. The present invention has the capability of sensing and recording pertinent battery reliability data under actual operating conditions. Reliability engineers can use this information to analyze different battery designs and to more precisely pinpoint when replacement of the battery is needed. 
     With additional reference to FIG. 3, the battery sensor device 10 includes a thin, generally flat substrate 22. Substrate 22 has two holes 24 and 26 therein that are aligned with the positive battery post 16 and negative battery post 18, respectively. Device 10 is designed so that it can be slipped over the battery posts 16 and 18 such that it lies essentially flush against the battery end face 20 as shown in FIG. 2. Device 10 is sufficiently thin that it does not impede the normal mating connection with the connector 14. As seen in FIG. 2, the connector 14 typically includes female receptacles 28 and 30 that receive posts 16 and 18, respectively. Connector 14 can be a standard ELCON battery connector. 
     Contacts 32 and 34 on device 10 make electrical contact with posts 16 and 18, respectively. In this example, contacts 32 and 34 are shown as conductive layers lining the sidewalls of the substrate 22 defining holes 24 and 26, respectively. Other contact constructions such as bendable fingers could, of course, also be used. 
     Substrate 22 contains one or more devices for detecting characteristics of the battery during operation. Preferably, the present invention utilizes the circuitry shown in FIG. 4 for sensing, recording and transmitting battery information. The sensors include current sensors 40 for sensing the current supplied from the battery 12. Suitable current sensors are available from Honeywell utilizing magneto-resistive technology. Temperature sensors 42 are employed to sense the ambient temperature to which the battery is exposed during use. Suitable temperature sensors include thermistors available from Honeywell. Voltage sensors 44 serve to sense the voltage supplied by battery 12. The voltage sensors are simple resistive dividers, whose voltage is read directly by the signal conditioning circuitry. 
     A real time clock and random access memory (RAM) 46 are also used in this particular embodiment. The real time clock is used to provide suitable clock signals for tagging events with the time of their occurrences. The functions of the clock and RAM can be provided, for example, by Part No. MCC146818 from Motorola. 
     The sensors 40, 42, 44 and clock/RAM 46 are fed into suitable signal conditioning circuitry 48. Signal conditioning circuitry 48 provides the necessary signal conditioning to interface the aforementioned components with microprocessor 50. Typically, signal conditioning circuitry 48 includes analog to digital converters and the like for converting analog signals from the sensors to digital data for use with the microprocessor 50. A commercially available example of suitable signal conditioning circuitry is the Tile Array signal conditioning circuitry available from Exar as Beta 180. Microprocessor 50, in this example, includes 12 kilobytes of read only memory (ROM) and is available from Motorola as component No. MCC68HC711. A non-volatile memory 52 serves to record and permanently store information. For example, microprocessor 50 can be used to create tables in memory 52 which record the current levels supplied by battery 12 per unit time. In other words, the microprocessor 50 stores information generated by the current sensor 40 on a timed basis provided by clock 46 and stores it in memory 52. Likewise, temperature and voltage data can be stored in memory 52. In this example, non-volatile memory 52 can be a 16 kilobyte memory provided by Xicor as component No. X28C64H. 
     The recorded battery information can be read from memory 52 through an output port provided by an RS-232 serial interface translator 54 which is available from Harris Semiconductor as ICL232. 
     The components making up the battery monitoring circuitry of FIG. 4 can be suitably arranged on the substrate 22 so as not to impede the normal connector-battery connection. In FIGS. 2 and 3 the circuitry components are generally indicated by the reference numeral 56. Components 56 are located in pockets 58 in the upper surface 60 of substrate 22. Components 56 thus do not appreciably extend above the surface 60. Electrical connection to the components 56 are made by traces on substrate surface 60. For example, trace 62 extends from positive battery post contact 32 to the pocket 58 and makes electrical connection with an appropriate component 56 (e.g., voltage sensor 44). Similarly, trace 64 extends from negative battery contact 34 to the voltage sensor to thereby monitor the voltage supplied via posts 16, 18 to the electrical equipment during use. It will be appreciated that, depending upon the degree of sophistication, more than one trace may be required and that the components 56 can be placed at various locations on substrate 22. The components, such as integrated circuit dies, are connected, for example, by conventional wire bonds between the die and the termination of the traces. A glob topcoating or other protective measures can be placed over the die, if desired. The top and bottom surfaces of the substrate 22 can also be covered with a suitable Kapton protective layer (not shown). 
     Trace(s) 66 extends from the component serving as a serial interface translator to an input/output port 68. Port 68 is suitably located near an edge of substrate 22 to receive an external connector, as will appear. A suitable power converter (not shown) is also preferably employed to take power from the battery post and convert it to levels suitable for powering the various components 56 such as microprocessor 50. An auxiliary backup battery may also be employed, if desired. 
     By way of non-limiting, yet specific examples, substrate 22 is a phenolic, nonconductive circuit board which is approximately 0.020 to 0.060 inch thick. In order to provide for proper mating with connector 12, the thickness of wafer 10 should be less than about 15 percent of the length of battery posts 16 and 18. 
     In operation, the device 10 is slipped over the battery posts 16 and 18 so that they extend through holes 24 and 26, with the substrate 22 lying essentially flush against battery end face 20. Connector 14 is then mated, in the normal fashion, with posts 16 and 18 to provide power to the electrical equipment which is schematically illustrated by box 70 in FIG. 1. As the battery is used to power equipment 70, the sensors 40, 42 and 44 continually provide information about the battery characteristics. This information can provide, for example, the number of charge/discharge cycles, the number and severity of deep-discharge cycles, total time spent in deep-discharge, and temperature fluctuations. Shock sensors and other similar sensors (not shown) could also be used to detect other operating environments such as the G-loads supplied to the battery. Microprocessor 50 can be suitably programmed to perform the desired data manipulation functions via input/output port 68. 
     The information stored in memory 52 is easily read from device 10. As shown in FIG. 5, a hand-held data collector 72 includes a cord 74 having a suitable connector 76 on one end thereof which slides over the edge of device 10 to make electrical contact with the traces of input/output port 68. Data can be read from memory 52 in a known manner so that the stored information is transmitted to data collector 72. If desired, the hand-held data collector 72 can later transmit this information to a larger computer 78 for further analysis. Collection of the data can be obtained without removing the sensor from the battery. All that is needed is to remove the connector 14 and make electrical connection with the input/output port 68. Alternatively, the sensor could be hard-wired to computer monitoring systems on the vehicle carrying the battery or other read-out devices. 
     It should be understood that while this invention has been described in connection with a particular example thereof, no limitation is intended thereby since obvious modifications will become apparent to those skilled in the art after having the benefit of studying the foregoing specification, drawings and following claims.