Abstract:
A battery management system used for monitoring battery pack characteristics for electric or hybrid vehicles. The battery management system includes a processing unit which is easily connected to a battery pack of a vehicle for testing the battery pack according to the test method of the present invention. The battery management system tests a battery pack and records, stores and analyzes test data. The battery management system may also transfer data to a computer unit. The computer unit can share data and analysis on a network or the Internet.

Description:
TECHNICAL FIELD 
     The present invention is related to a method and apparatus for monitoring batteries and, more particularly to an improved method and apparatus for monitoring battery systems of a golf car. 
     DISCUSSION 
     In recent times, an increasing amount of research and development has been directed toward extending the life of battery packs used to power electric or hybrid vehicles. Improvements in battery life result in greater utility of the particular vehicle and lower overall costs. The lower costs inure to both the vehicle manufacturer, in the form of reduced warranty, and to the vehicle owner, in the form of reduced repair, trouble shooting, and replacement. 
     A particular area of research focuses on the operational characteristics of a battery pack during its lifetime. Battery packs generally comprise multiple batteries connected in series or parallel fashion. As such, poor operation of a single battery within the battery pack can degrade operation of the battery pack as a complete unit. Thus, it is important to be able to test the battery packs and monitor individual battery characteristics. 
     Traditional testing methods monitor individual battery voltage and require, in sequence, that the battery pack be fully charged, discharged, individual voltages measured, and recharged to put the vehicle back into service. Such methods are not cost effective in that a particular vehicle must be removed from operation for an extended period of time in order to complete the test and fully charge the battery pack for further use. Additionally, traditional test apparatuses are inefficient because the battery pack and individual batteries must be directly accessible. 
     Additionally, battery pack performance is a concern for particular parties. For example, the golf industry utilizes fleets of battery powered golf cars for carrying golfers and clubs around golf courses. As such, a golf club&#39;s management is concerned with the operation and battery life of the golf cars which they purchase from manufacturers. The golf car manufacturers are also concerned about the quality of golf car they are providing to their customers. Finally, the battery pack manufacturers are also concerned about the quality of battery packs which they are providing to their customers and warranty costs which they will incur as the result of poor battery performance. 
     It is therefore desirable to provide a battery management system which can efficiently monitor the operational life of a series of batteries within a battery pack. 
     It is further desirable to provide a battery management system which can record and analyze historical data of battery packs and share the data with other concerned parties in remote locations. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a battery management system for testing batteries of an electric or hybrid vehicle. In particular, the present invention enables an operator to monitor the quality of particular batteries in a battery pack during the lifetime of the battery pack. As such, an operator is able to determine when a particular battery need be replaced. Furthermore, the battery management system enables analysis and distribution of battery pack information to concerned parties. 
     A battery management system is provided for managing a battery pack of an electric or hybrid vehicle. The battery pack includes a plurality of batteries. The battery management system includes a first interface component, in electrical communication with the battery pack and a second interface component in selective electrical communication with the first component. A circuit is also included which is in electrical communication with a second interface component. The circuitry is adapted to measure a first parameter of each of the batteries of the battery pack and compare the first parameter of a particular battery to the remaining batteries. An output is further provided for signaling an operator if a result of the first parameter comparison is not within a predetermined range. 
     The method of the present invention is implemented for testing a battery pack of an electric or hybrid vehicle when the battery pack comprises a plurality of batteries. The method of the present invention includes the steps of measuring a first parameter of each battery of the battery pack, selecting the first parameter value of a particular battery of the battery pack, determining an average first parameter value of the remaining batteries of the battery pack, determining a result in value of a function of the isolated first parameter and the average first parameter value of the remaining batteries, providing an alert signal if the result in value is not within a predetermined range. This process is then repeated for each battery of the battery pack. 
     The battery management system can also be in communication with a computer system. The computer system can further analyze battery pack information and transmit results or other information via a network, to concerned parties. 
     One advantage of the present invention is that a simplified, nonintrusive solution is provided for monitoring the lifetime performance of a battery pack. 
     A second advantage of the present invention is that each battery of the battery pack is monitored and the data from each battery can be stored for analytical purposes. In this way, specific problems within the battery pack, during the lifetime of the battery pack, can be identified easily and dealt with quickly. 
     Another significant advantage of the present invention is the speed of the testing process. The present invention eliminates charge and discharge steps of traditional battery testing systems, enabling a vehicle to be quickly tested and put back into service. 
     A further advantage of the present invention is the quick accessibility of the battery pack and the battery to the testing apparatus. 
     For a more complete understanding of the invention, its objects and advantages, reference should be made to the following specification and to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings, which form an integral part of the specification, are to be read in conjunction therewith, and like reference numerals are employed to designate identical components in the various views: 
     FIG. 1 is a schematic view of the battery management system according to the principles of the present invention; and 
     FIG. 2 is a flow diagram of the operation of the battery management system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a battery management system  1  for monitoring and testing a battery pack of an electric or hybrid vehicle. With particular reference to FIG. 1, an electric or hybrid vehicle  10 , such as a golf car, is shown. In a preferred embodiment, the vehicle  10  includes a battery pack  12  comprising six individual six-volt batteries  14 , labeled sequentially  14   a  through  14   f . Thus, the preferred embodiment is a 36-volt system. It should be noted, however, that the present invention is equally applicable to other voltage systems, including 12 volt and 24 volt systems. This configuration is merely exemplary in nature and it should be appreciated that the number and rating of the batteries  14  may be varied. Each battery  14  has a positive and a negative terminal  16 ,  18 , respectively. The batteries  14  of the battery pack  12  are shown preferably connected in a series configuration. As such, the positive terminal  16  of the first battery is in electrical communication with the negative terminal  18  of the second battery, whose positive terminal  16  is in electrical communication with the negative terminal  18  of a third battery and so on. The battery pack  12  is in electrical communication with an electric motor  13  for driving the vehicle  10 . 
     The vehicle also includes an interface component  20  which is interconnected with the battery pack  12 . Specifically, the interface component  20  includes seven leads (a, b, c, d, e, f, g) to the battery pack  12 . The first lead (a) is connected to the negative output terminal of the battery  14   a , the second lead (b) is connected to the series connection between battery  14   a  and battery  14   b , the third lead (c) is connected to the series connection between the battery  14   b  and battery  14   c , the fourth lead (d) is connected to the series connection between the battery  14   c  and battery  14   d , the fifth lead (e) is connected to the series connection between battery  14   d  and battery  14   e , the sixth lead (f) is connected to the series connection between the battery  14   e  and battery  14   f , and the seventh lead (g) is connected to the positive output terminal of the battery  14   f.    
     The vehicle  10  can optionally include a memory unit  22  which is able to store information such as vehicle number, battery ID, and other desired details. The memory unit  22  is also connected to the interface component  20  and may communicate using any of a number of serial or parallel communications protocols. The battery management system  1  includes a processing unit  2  having a second interface component  24  which is selectively connectable to the interface component  20  of the vehicle  10 . The processing unit  2  further includes a circuit  26  which connects to the second interface component  24 . The circuit  26  also connects to a microprocessor  28  to send and receive communication signals. The microprocessor  28  interconnects to a memory unit  30 . The memory unit  30  is of a read/write variety, storing recorded data, instructions and algorithms for running the battery management procedure. 
     The microprocessor  28  also communicates with an input device  32 . The input device  32  could include a keyboard, a keypad, a touch pad, or other device commonly known in the art. The input device  32  may be used by an operator to input information or select from a variety of process parameters. Additionally, the microprocessor  28  interconnects to an output device  34  for outputting information and results from the battery management procedure. The output device  34  could include a display screen or other device commonly known in the art. The microprocessor  28  implements the battery testing procedure of the present invention, discussed in detail below, and performs all required calculations. 
     The processing unit  2  also includes an output connector  36  for connection with an input connector  38  of a computer unit  40 . In this manner, the processing unit  2 , which may be portable, is able to download test information to the computer unit  40 . In turn, the computer unit  40  may be in communication with a network or the Internet for further communicating test information with other concerned parties, such as the battery pack manufacturer or a warranty center. Alternatively, the computer unit  40  may be connected to a database  42  which is further connected to a network or the Internet. The computer unit  40  may also program or reprogram the processing unit  2  in order to update the test procedure as necessary. The computer unit  40  may also communicate with the memory  22  through the processing unit  2 . 
     FIG. 2 shows a flow chart outlining the monitoring procedure of the present invention. Once the monitoring procedure has been initiated by the microprocessor  28 , the microprocessor  28  sets a first variable N equal to zero and a second variable J equal to the number of batteries  14  within the battery pack  12  at step  100 . The microprocessor  28  is able to automatically determine the number of batteries  14  within the battery pack  12  through information received from the memory unit  22 . 
     In a first preferred embodiment at step  110 , the circuit  26  measures the conductance of each battery  14  in the battery pack  12  and sends a signal to the microprocessor  28  that varies in accordance with the measured conductance. Measuring the conductance may be carried out using procedures and devices described in U.S. Pat. No. 5,945,829 to Bertness. This patent is incorporated by reference herein. In a second preferred embodiment at step  110 , the circuit  26  measures the impedance or conductance of each battery  14 . The variable N is then increased by one at step  120 . At step  130 , the microprocessor  28  selects the measured value of a particular battery (battery N) as a comparison value. At step  140 , the microprocessor  28  calculates the average measured value of the remaining batteries  14 . The average measured value of the remaining batteries  14  is compared to the comparison value of the particular battery to determine a resultant value at step  150 . The microprocessor  28  determines whether or not this resultant value falls within a predetermined range at step  160 . The predetermined range is pre-set by battery manufacturer standards. 
     If the resultant value falls outside of the predetermined range, an alert is signaled at step  170  and the result is recorded at step  180 . The alert may be provided on the output device  34 , or be an audible signal given by a speaker  42 , or even a visual signal from a light  44 . If the result does not fall outside of the predetermined range the result is recorded at step  180 , without alert. The microprocessor  28  determines whether N is equal to J, at step  190 , thus determining whether each battery  14  of the battery pack  12  has been tested. If N is not equal to J the process is repeated beginning at step  120 . If N is equal to J then the test is complete at step  200 . 
     While the invention has been described in its presently preferred form, it is to be understood that there are numerous applications and implementations for the present invention. Accordingly, the invention is capable of modification and changes without departing from the spirit of the invention as set forth in the appended claims.