Patent Publication Number: US-6909287-B2

Title: Energy management system for automotive vehicle

Description:
The present invention is a divisional of application Ser. No. 09/564,740, filed May 4, 2000 is now U.S. Pat. No. 6,331,762 which claims priority to Provisional Application Ser. No. 60/132,622, filed May 5, 1999, and entitled AUTOMOTIVE VEHICLE BATTERY CHARGING SYSTEM; U.S. Provisional Application No. 60/165,208, filed Nov. 12, 1999, and entitled ENERGY MANAGEMENT SYSTEM FOR AUTOMOTIVE VEHICLE; and Provisional Application Ser. No. 60/175,762, filed Jan. 12, 2000, and entitled ENERGY MANAGEMENT SYSTEM FOR AUTOMOTIVE VEHICLE, which are incorporated herein by reference in their entirety. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to automotive vehicles. More specifically, the present invention relates to an energy management and monitor system for a battery of an automotive vehicle. 
   Automotive vehicles powered by combustion engines typically include a battery. The battery is used to power the electrical system when the engine is not running. Additionally, the engine is used to charge the battery. The engine is also used to power electrical components of the vehicle when the engine is running. 
   Vehicles contain charging systems, simply referred to as an “alternator,” which are powered by the engine and used to charge the battery. Typical prior art charging systems have been a simple voltage regulator connected to the output of an alternator. The voltage regulator is used to set a voltage generated by the alternator which is applied to the battery. However, this technique does not take into account the actual condition of the battery as the voltage across the battery is not an accurate representation of the battery&#39;s condition. Additionally, such systems do not provide any information about the use of the battery, or the battery&#39;s current state of charge or state of health. 
   SUMMARY OF THE INVENTION 
   Various aspects of the present invention provide a method and/or an apparatus for monitoring or controlling charging of a battery in a vehicle. In one aspect, a method is provided for charging a battery in a vehicle having an internal combustion engine configured to drive an alternator electrically coupled to the battery and adapted to charge the battery with a charge signal applied to the battery. The method includes coupling to the battery through a four point Kelvin connection, measuring a dynamic parameter of the battery using the Kelvin connection, where the dynamic parameter measurement a function of a time varying signal. A condition of the battery as a function of the measured dynamic parameter. The charge signal from the alternator is controlled in response to the determined condition of the battery. 
   In another aspect, an apparatus for monitoring the condition of a storage battery while the storage battery is coupled in parallel to an electrical system of an operating vehicle is provided. The apparatus includes a first electrical connection directly coupled to a positive terminal of the battery, a second electrical connection directly coupled to a negative terminal of the battery, and the first and second electrical connections are coupled to a voltage sensor to measure a time varying voltage across the battery. A third electrical connection is directly coupled to the positive terminal of the battery and a fourth electrical connection directly is coupled to a negative terminal of the battery, the third and fourth electrical connections are coupled to a forcing function having a time varying component. In one aspect, a current sensor is provided which is electrically in series with the battery. A microprocessor is configured to determine the condition of the battery as a function of a dynamic parameter of the battery based upon the measured voltage and the forcing function. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a simplified block diagram showing a battery monitor in a vehicle in accordance with one embodiment of the present invention. 
       FIG. 2  is a more detailed schematic diagram showing the battery monitor of FIG.  1 . 
       FIG. 3  is a simplified block diagram showing steps in performing diagnostics in accordance with one aspect of the present invention. 
       FIG. 4  is a simplified block diagram showing steps in collecting data for use with the present invention. 
       FIG. 5  is a simplified block diagram which illustrates performing diagnostics on a starter motor of the vehicle of FIG.  1 . 
       FIG. 6  is a simplified block diagram showing steps related to adjusting the charging profile for charging the battery of the vehicle of FIG.  1 . 
       FIG. 7  is a graph which illustrates one sample curve of regulator voltage output versus state of charge for the battery of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
   The present invention offers an apparatus and method for monitoring the condition of the battery and controlling charging of the battery. Such a method and apparatus can be part of a general energy management system for a vehicle. 
     FIG. 1  is a simplified block diagram showing an automotive vehicle  10  which includes a battery monitor  12  in accordance with one embodiment of the present invention. Vehicle  10  includes vehicle loads  14  which are shown schematically as an electrical resistance. A battery  18  is coupled to the vehicle load  14  and to an alternator  20 . Alternator  20  couples to an engine of the vehicle  10  and is used to charge battery  18  and provide power to loads  14  during operation. 
   In general, automotive vehicles include electrical systems which can be powered when the engine of the vehicle is operating by a generator, or alternator. However, when the engine is not running, a battery in the vehicle is typically used to power the system. Thus, the standard generator system in a vehicle serves two purposes. The generator is used to supply power to the vehicle loads, such as lights, computers, radios, defrosters and other electrical accessories. Further, the generator is used to recharge the battery such that the battery can be used to start the vehicle and such that the battery may power the electrical accessories when the engine is not running. 
   A standard generator system typically consists of a three phase AC alternator coupled to the engine by a belt or a shaft, rectification diodes and a voltage regulator. These components may exist separately or be part of an integral unit and are typically, somewhat inaccurately, referred to as an “alternator”. The voltage regulator is configured such that a constant voltage is supplied by the charging system, regardless of the current being drawn by the electrical system. The actual load applied to the generator system varies depending upon the number of accessories that are activated and the current required to recharge the battery. Typical values for the voltage regulator output are between 13.5 and 15.5 volts, depending upon the vehicle manufacturer and particular battery chemistry. Further, the voltage on a specific vehicle can also be compensated for ambient temperature. 
   This prior art approach has a number of draw backs. The output voltage of the generator must be selected to be high enough to rapidly charge the battery under any condition and regardless of the state of charge of the battery. Electrical loads on the vehicle are designed to operate at 12.6 volts, the voltage provided by the battery when the engine is switched off. However, these electrical loads must also operate at the higher voltage supplied when the generator system is on. This higher voltage which is impressed upon the electrical system causes higher I 2 R (resistive) losses in the loads due to the increased voltage level. This wastes energy and causes the components to heat. This results in reduced life of the electrical circuitry, higher operating temperatures and wasted energy which must ultimately come from the primary fuel source used to operate the engine. 
   The high voltage across the battery is necessary when the battery&#39;s state of charge is low in order to rapidly recharge the battery. However, when the battery&#39;s state of charge is within an acceptable range (which occurs most of the time at normal driving speeds), the high voltage across the battery results in high I 2 R (resistive heating) losses within the battery resulting in waste of energy, heating of the battery causing premature battery failure, gassing of the battery also resulting in premature failure and heating of electrical components causing premature component failure. 
   One aspect of the present invention includes the recognition of the aforementioned problems associated with prior art battery charging techniques. In one aspect of the present invention, a battery charging system controller is provided which monitors the condition of the battery under charge and controls the charging system in response to the condition of the battery. With such general aspects of the invention, the particular implementation of the battery monitor and charge control can be selected as appropriate. 
   In the embodiment illustrated in  FIG. 1 , battery monitor  12  includes a microprocessor  22  coupled to a voltage sensor  24 , a current sensor  26  and a forcing function  28 . Microprocessor  22  may also include one or more inputs and outputs illustrated as I/O  30  adapted to couple to an external databus or to an internal databus associated with the vehicle  10 . Further, a user input/output (I/O)  32  is provided for providing interaction with a vehicle operator. In one embodiment, microprocessor  22  is coupled to alternator  20  to provide a control output  23  to alternator  20  in response to inputs, alone or in various functional combinations, from current sensor  26 , voltage sensor  24  and forcing function  28 . In one embodiment, the control output  23  is configured to control alternator  20  such that a nominal voltage output from alternator  20  is 12.6 volts, typical of the nominal open-circuit voltage of the battery  18 . Further, microprocessor  22  can raise the output voltage from alternator  20  in accordance with an inverse relationship to the state of charge of battery  18 . This can be configured such that alternator  20  only charges battery  18  when necessary, and only charges battery  18  as much as is necessary. This charging technique can increase battery life, lower component temperature of loads  14 , increase the lifespan of loads  14  and save fuel. This configuration provides a feedback mechanism in which the state of charge of battery  18  is used to control the charging of battery  18 . The battery monitor  12  is easily installed in a vehicle electrical system. A single shunt current sensor  26  must be inserted in one of the primary battery cables and a control line provided to allow control of alternator  20 . The control can be by simply adjusting the voltage supplied to a voltage regulator of alternator  20  to thereby control charging of battery  18 . The battery monitor  12  can be a separate, self-sufficient and self-contained monitor which operates without requiring interaction with other components of the vehicle, except in some embodiment, alternator  20 . 
     FIG. 1  also illustrates a Kelvin connection formed by connections  36 A and  36 B to battery  18 . With such a Kelvin connection, two couplings are provided to the positive and negative terminals of battery  18 . This allows one of the electrical connections on each side of the battery to carry large amounts of current while the other pair of connections can be used to obtain accurate voltage readings. Because substantially no current is flowing through the voltage sensor  24 , there will be little voltage drop through the electrical connection between sensor  24  and battery  18  thereby providing more accurate voltage measurements. In various embodiments, the forcing function  28  can be located physically proximate battery  18  or be connected directly to battery  18 . In other embodiments, the forcing function  28  is located anywhere within the electrical system of vehicle  10 . In one aspect, the present invention includes an in-vehicle battery monitor  12  which couples to battery  18  through a Kelvin connection and further may optionally include a current sensor  26  and may be capable of monitoring battery condition while the engine of vehicle  12  is operated, loads  14  are turned on and/or alternator  20  is providing a charge signal output to charge battery  18 . In one particular embodiment, the combination of the Kelvin connection formed by connections  36 A and  36 B along with a separate current sensor  26  connected in series with the electrical system of the vehicle  10  is provided and allows monitoring of the condition of battery  18  during operation of vehicle  10 . The use of an current sensor  26  is used to provide a monitor of the total current I T  flowing through battery  18 . 
   In operation, microprocessor  22  is capable of measuring a dynamic parameter of battery  18 . As used herein, a dynamic parameter includes any parameter of battery  18  which is measured as a function of a signal having an AC or transient component. Examples of dynamic parameters include dynamic resistance, conductance, admittance, impedance or their combinations. In various aspects of the invention, this measurement can be correlated, either alone or in combination with other measurements or inputs received by microprocessor  22 , to the condition or status of battery  18 . This correlation can be through testing of various batteries and may be through the use of a lookup table or a functional relationship such as a characterization curve. The relationship can also be adjusted based upon battery construction, type, size or other parameters of battery  18 . Examples of various testing techniques are described in the following references which are incorporated herein by reference U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 4,816,768, issued Mar. 28, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE; U.S. Pat. No. 4,825,170, issued Apr. 25, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE WITH AUTOMATIC VOLTAGE SCALING; U.S. Pat. No. 4,881,038, issued Nov. 14, 1989, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE WITH AUTOMATIC VOLTAGE SCALING TO DETERMINE DYNAMIC CONDUCTANCE; U.S. Pat. No. 4,912,416, issued Mar. 27, 1990, to Champlin, entitled ELECTRONIC BATTERY TESTING DEVICE WITH STATE-OF-CHARGE COMPENSATION; U.S. Pat. No. 5,140,269, issued Aug. 18, 1992, to Champlin, entitled ELECTRONIC TESTER FOR ASSESSING BATTERY/CELL CAPACITY; U.S. Pat. No. 5,343,380, issued Aug. 30, 1994, entitled METHOD AND APPARATUS FOR SUPPRESSING TIME VARYING SIGNALS IN BATTERIES UNDERGOING CHARGING OR DISCHARGING; U.S. Pat. No. 5,572,136, issued Nov. 5, 1996, entitled ELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATION FOR LOW STATE-OF-CHARGE; U.S. Pat. No. 5,574,355, issued Nov. 12, 1996, entitled METHOD AND APPARATUS FOR DETECTION AND CONTROL OF THERMAL RUNAWAY IN A BATTERY UNDER CHARGE; U.S. Pat. No. 5,585,728, issued Dec. 17, 1996, entitled ELECTRONIC BATTERY TESTER WITH AUTOMATIC COMPENSATION FOR LOW STATE-OF-CHARGE; U.S. Pat. No. 5,592,093, issued Jan. 7, 1997, entitled ELECTRONIC BATTERY TESTING DEVICE LOOSE TERMINAL CONNECTION DETECTION VIA A COMPARISON CIRCUIT; U.S. Pat. No. 5,598,098, issued Jan. 28, 1997, entitled ELECTRONIC BATTERY TESTER WITH VERY HIGH NOISE IMMUNITY; U.S. Pat. No. 5,757,192, issued May 26, 1998, entitled METHOD AND APPARATUS FOR DETECTING A BAD CELL IN A STORAGE BATTERY; U.S. Pat. No. 5,821,756, issued Oct. 13, 1998, entitled ELECTRONIC BATTERY TESTER WITH TAILORED COMPENSATION FOR LOW STATE-OF-CHARGE; U.S. Pat. No. 5,831,435, issued Nov. 3, 1998, entitled BATTERY TESTER FOR JIS STANDARD; U.S. Pat. No. 5,914,605, issued Jun. 22, 1999, entitled ELECTRONIC BATTERY TESTER; U.S. Pat. No. 5,945,829, issued Aug. 31, 1999, entitled MIDPOINT BATTERY MONITORING; U.S. Pat. No. 6,002,238, issued Dec. 14, 1999, entitled METHOD AND APPARATUS FOR MEASURING COMPLEX IMPEDANCE OF CELLS AND BATTERIES; U.S. Pat. No. 6,037,777, issued Mar. 14, 2000, entitled METHOD AND APPARATUS FOR DETERMINING BATTERY PROPERTIES FROM COMPLEX IMPEDANCE/ADMITTANCE; and U.S. Pat. No. 6,051,976, issued Apr. 18, 2000, entitled METHOD AND APPARATUS FOR AUDITING A BATTERY TEST. 
   In the specific embodiment illustrated in  FIG. 1 , the forcing function is a function which applies a signal having an AC or transient component to battery  18 . The forcing function can be through the application of a load which provides a desired forcing function in which current is drawn from battery  18 , or can be through active circuitry in which a current is injected into battery  18 . This results in a current labeled I F  in FIG.  1 . The total current, I T  through battery  18  is due to both the forcing function current I F  and the current flowing through loads  14 , I L . Current sensor  26  is positioned to sense the total current I L . One example battery dynamic parameter, the dynamic conductance (or reciprocally the battery resistance) can be calculated as: 
    ΔG=V=ΔI T /ΔV  EQ. 1 
   where ΔV is the change in voltage measured across the battery  18  by voltage sensor  24  and ΔI T  is the change in total current measured flowing through battery  18  using current sensor  26 . Note that Equation 1 uses current and voltage differences. In one embodiment, the change in voltage and change in current are measured over a period of 12.5 seconds and at a rate of 50 msec to thereby provide a total of 20 readings for ΔV and ΔI T  every second. The forcing function  28  is provided in order to ensure that the current through battery  18  changes with time. However, in one embodiment, changes in I L  due to loads  14  or the output from alternator  20  can be used alone such that ΔI T =ΔI L  and the forcing function  28  is not required. 
   In one embodiment, the voltage and current sensors provide synchronized operation, within one microsecond, and are substantially immune to measurement errors due to network propagation delays or signal line inductance. Furthermore, microprocessor  22  can detect a failure of the voltage regulator and alternator  20  if the voltage output exceeds or drops below predetermined threshold levels. This information can be provided to an operator through user interface  32 , for example, a “service regulator soon” indication. 
   A temperature sensor  37  is provided which can be coupled directly to one of the terminals of the battery  18  for measuring battery temperature. The temperature sensor  37  can be used in determining the condition of the battery, as battery condition is a function of temperature and can be used in estimating the amount of power which will be required to start the engine of the vehicle. Any type of temperature sensor can be used, for example, a thermistor, thermocouple, RTD, semiconductor or other temperature sensor. 
   In one embodiment, current sensor  26  comprises a resistance shunt of 250 μohms and current through the shunt is determined by measuring the voltage drop across the shunt. However, other types of current measurement techniques can also be used such as Hall Effect sensors or through an inductance probe. The change of voltage across the battery and the resultant change in current through the battery is sampled using, for example, one or more analog to digital converters. This information can be correlated to determine the total capacity, such as the total Cold Cranking Amp (CCA) capacity of the battery. 
   Note that during the measurement cycle, vehicle loads  14  may be applied unexpectedly causing noise to be present in the measurements. One technique which might be considered to reduce the noise is to discard those samples which are outside of a predetermined or adjustable window or are outside of the dynamic range of the analog to digital converter. However, quite unexpectedly it has been found that the accuracy of measurements can be increased by increasing the dynamic range of the analog to digital converters, at the expense of the accuracy of the samples obtained from the converter. By averaging all of the samples, even those which are statistically large or small relative to other samples, the present invention is capable of providing accurate voltage and current measurements even in a noisy environment. By averaging samples, and providing sufficient dynamic range for the analog to digital converter, no samples will be discarded and errors in the measurements will tend to cancel against other errors. 
   In general, the present invention uses the direct relationship between the dynamic conductance of the battery and the condition of the battery. For example, if a battery drops more than 15% below its rated capacity, microprocessor  22  can provide an output which indicates that the battery  18  should be replaced. Further, the conductance can be used to determine the charge level of the battery. Such a measurement can be augmented to improve accuracy by monitoring the total current flowing into battery  18 , or out of battery  18 , using current sensor  26 . The voltage across the battery  18  can also be used to determine the charge used in the determination of charge level. In general, the state of charge can be determined as a function of various combinations either alone or together of battery state of health, temperature, charge balance (charge going into and out of the battery), charging efficiency and initial conditions such as the battery construction, manufacture, plate configuration or other conditions of the battery. The functional relationship can be determined by characterizing multiple batteries or through the use of artificial intelligence techniques such as neural networks. 
     FIG. 2  is a more detailed schematic diagram of battery monitor  12 .  FIG. 2  shows microprocessor  22  which includes a memory  40 .  FIG. 2  illustrates I/O  32  with which can be, for specific examples, a communication link in accordance with various standards such as J1850, J1708, J1939, etc. Memory  40  is shown as an internal memory. However, external memory or an optional external memory  42  can also be provided. In general, memory is provided for storing programming functions, ratings, variables, etc. Microprocessor  22  can be a microcontroller or any type of digital circuitry and is not limited specifically to a microprocessor.  FIG. 2  illustrates forcing function  28  in greater detail and includes a resistance R 1    44  and a switch S 1    46  controlled by microprocessor  22 . Switch  46  can be, for example, a field effect transistor. Voltage sensor  24  is shown as including a differential amplifier  47  coupled to battery  18  through a DC blocking capacitor C 1    48 . Shunt  26  is illustrated as a resistance R 2    50  and a differential amplifier  52 . Switches S 2    54  and S 3    56  are positioned to selectively couple amplifiers  52  and  47 , respectively, to microprocessor  22  and are actuated by a sample control line to provide data samples to microprocessor  22 . An analog to digital converter can be an integral part of microprocessor  22  or it can be a separate component to digitize the outputs from amplifiers  47  and  52 . Capacitors C 2  and C 3  provide sample and hold circuits. 
   Forcing function  28  can be formed by resistance as illustrated in  FIG. 2 , or by a current sink or through an existing load of the vehicle. Switch S 1    46  can be an FET, or biopolar transistor or can be a mechanical or existing switch in the automotive vehicle. Although shunt  26  is illustrated with a shunt resistance, other types of current sensors such as Hall effect sensors or cable resistance based sensors can be used. Other types of DC blocking techniques can be used to replace capacitancy C 1    48  such as a DC coupled amplifier. 
     FIG. 3  is a simplified block diagram  100  showing diagnostic steps performed by microprocessor  28  in accordance with the invention. At blocks  102  and  104 , the dynamic parameter(s) for the battery  18  are obtained and at block  104  data is collected. The type of data collected at block  104  can be any type of data used in determining the condition of the battery. For example, the data can be values used for ΔV and ΔI T , information related to the type of battery, etc. This information can be stored in memory  40  for subsequent retrieval by microprocessor  22 . The data can be collected over any time period and during any type of engine or battery operation. At block  106 , microprocessor  22  performs diagnostics based upon the data stored in memory  40 . If a battery fault or impending fault is detected, an output can be provided at block  108  such as providing a “service battery soon” indication on the dash of the vehicle  10 . 
   Various aspects of the invention include the particular diagnostics performed by diagnostic block  106 . The diagnostics can be simple diagnostics such as a simple if-then rule in which the collected data is compared to various thresholds to provide the diagnostic output. Absolute values of the data can be used for this comparison or various statistical operations can be performed on the data for use in the comparison. For example, averages or standard deviation of the data can be compared to a threshold. The threshold levels can be determined through testing of the vehicle and entered into memory  40  during manufacture. Preferably, when battery  18  is replaced, the thresholds are updated accordingly. 
   In more advanced embodiments of the diagnostic block  106 , microprocessor  22  can perform diagnostics using fuzzy logic, neural networks or artificial intelligence techniques. Neural networks can advantageously be used as they do not require that the battery, alternator and vehicle loads be modeled. Instead, neural networks are capable of learning what “normal” data collected at step  104  should be, and can provide an indication when a pattern of the data is drifting outside of normal operation. Further, the neural network can be “trained” to recognize potential sources of the failure and provide an expected time until the system completely fails. These diagnostic techniques can be selected and implemented such that the operator is warned of an impending failure, prior to the complete failure of the battery  18  or alternator  20 . 
     FIG. 4  is a block diagram  130  showing example steps in accordance with data collection and calculation of a dynamic parameter in accordance with the present invention. Of course, as should be pointed out with respect to all of the flow charts set forth herein, those skilled in the art will recognize that the particular functions of the blocks and the order in which the blocks are executed can be easily rearranged and the invention is not limited to the specific embodiments set forth herein. 
   In block diagram  130 , at block  132  microprocessor  22  obtains an initial voltage V 1  across battery  18  using voltage sensor  24  and an initial current I T1  through battery  18  using current sensor  26 . Next, the forcing function  28  is applied to battery  18  at step  133 . At block  134 , microprocessor  22  obtains values V 2  and I T2  with the forcing function applied, and at step  136  the forcing function is removed. Values for ΔV and ΔI T  are calculated at step  138 . In one example embodiment, the forcing function is applied for a duration of 100 μSec 20 times every second. N values are obtained at block  140 . In one example, N is equal to 256. At block  142 , the average of ΔV and I T2  for the N samples is calculated and a dynamic parameter for the batter  18  is determined at block  144 . This dynamic parameter can be correlated to a condition of the battery at block  146  and displayed on user I/O  32 , output through I/O  30  or used to control alternator  20  through alternator control  23 . 
   In one aspect of the invention, the battery monitor performs a state of charge measurement, in real time and regardless of battery polarization, and automatically corrects for the state of health of the battery and the battery temperature. In general, state of health can be determined as a function of the battery conductance and the open circuit voltage across battery  18 . For example, the state of health can be determined as:
 
SOH=k 1 (G/RATING) * f(V OC )−k 2   EQ. 2
 
where k 1  and k 2  are constants which are related to the type of battery, G is the measured conductance of the battery, rating is a rating for the battery and f(V OC ) is a relationship between the state of charge and the open circuit voltage of the battery as set forth in the aforementioned Champlin and Midtronics, Inc. patents. The state of health will range between 0 and 100%. Using the state of health determined by Equation 2, the state of charge (from 0 to 100%) can be determined in accordance with Equation 3: 
               SOCt   2     =       100   *       [       ∫     t   1       t   2       ⁢     i   ⁢     ⅆ   t     ⁢       ∫     t   1       t   2       ⁢       e   ⁡     (   T   )       ⁢     ⅆ   t     ⁢       ∫     t   1       t   2       ⁢       e   ⁡     (   i   )       ⁢     ⅆ   t                 ]         (   SOH   )     ⁢     (     AMP   -   HOURCAPACITY     )           +     SOC     t   1                 EQ   .           ⁢   3             
 
where t 1  is the time at which the state of charge is known (i.e., from the period of overcharge, for example), t 2  is the present time, i is the current (amps) in or out of the battery at time t, T is the battery temperature, e(T) is the charge acceptance efficiency at temperature T, and e(i) is the charge acceptance efficiency at current i. Of course, Equations 2 and 3 are simply examples of state of health and state of charge measurements and other techniques can be used in accordance with the invention.
 
   Using the battery state of charge and the battery state of health, battery monitor  12  can predict the starting capabilities of a starter motor of vehicle  10 . For example, by comparing the amount of current measured by current sensor  26  which has been previously been required to start the engine of vehicle  10  for a particular temperature, microprocessor  22  can determine if the current state of charge of the battery for the current state of health at the current temperature will be sufficient to provide enough current to start the engine. The performance and any degradation in the starter motor can also be taken into account by microprocessor  22 . For example, if the amount of current required to start the engine has been increasing with time, microprocessor  22  can extrapolate and predict what amount of current will be required to start the engine in the future.  FIG. 5  is a simplified block diagram  200  which illustrates steps performed by a microprocessor  22  in diagnosing the starting capability of battery  18 . At block  202 , microprocessor  22  determines the starting capability of battery  18 . For example, the starting capability can be an estimation or measurement of the amount of current which battery  18  can supply over a short duration. At block  204 , microprocessor  22  estimates the starting requirements of the starting motor of the engine of vehicle  10 . For example, the past requirements of the starter motor can be recalled from memory  40  and any trend can be used to predict what will be required for starting the engine. Other inputs can also be used in this determination such as the current temperature. At block  206 , a starter diagnostic output is provided. For example, if it appears that the battery will have difficulty in operating the starter motor for a sufficient duration to start the motor of the vehicle, vehicle loads  14  can be selectively switched off by microprocessor  22  through I/O  30 . Additionally, a warning can be provided to an operator through user I/O  32  of an impending problem, prior to its actual occurrence, such that the battery  18  can be replaced. 
   In another aspect of the invention, microprocessor  22  can be adapt or alter the performance of the engine and/or loads  14  based upon a number of different parameters in order to provide optimal charging to battery  18 . For example, microprocessor  22  can interface to a data bus of a microprocessor of the vehicle  10  through I/O  30  to control engine operation. Alternatively, microprocessor  22  can be the same microprocessor used to control vehicle operation. The microprocessor  22  can adjust the idle speed of the engine, shift points of the transmission and the load placed on the electrical system by some of the loads  14  to increase or decrease the rate of battery charging based upon the expected driving patterns of an operator. For example, if the microprocessor has observed that the vehicle is normally operated for a short duration, the microprocessor  22  can increase the idle speed of the engine and attempt to reduce loads placed on battery  18  to increase the charging rate of battery  18 . Further, microprocessor  22  can alter the shift points of the transmission to cause the engine to operate at a high (or lower) speed than normal. The prediction of engine operation can also be based upon time of day and the day of the week such that repeated driving patterns can be accounted for, for example, commuting to work. Further, in vehicles where it is possible to recognize the operator of the vehicle, such as through the seat position memory in a power seat of the vehicle, microprocessor  22  can alter the charging pattern based upon the driving characteristics of a specific driver. 
     FIG. 6  is a simplified block diagram flowchart  250  showing steps performed by microprocessor  22  in adjusting engine speed or loads to control the charge in battery  18 . Block  252 , microprocessor  22  determines the charge required by battery  18  to become is fully charged, this determination can be based upon a measurement of the current charge level of battery and a determination of the maximum amount of charge that battery  18  can hold, for example, as a function of the state of health of battery  18 . At block  254 , microprocessor  22  predicts the expected driving pattern for the upcoming engine use. At block  256 , microprocessor  22  adjusts the engine operation and/or vehicle loads  14  in order to optimize the charging of the battery  18  based upon the charge required as determined at step  252  and the driving pattern predicted at step  254 . During engine operation, microprocessor  22  continues to monitor the battery state of charge at block  258  and adjusts the charging accordingly at block  260 . Once battery  18  has been fully charged, the microprocessor  22  can reduce the charging rate as appropriate. 
   If the drive cycle is, or has tendency to be, insufficient to charge the battery  18 , microprocessor  22  can provide an output to an operator through user I/O  32  to indicate that either the vehicle must be driven for an extended period of time or an alternative charging method be used to charge battery  18 . An indication can also be provided as to a prediction regarding how many further such drive cycles can be supported by the battery  18  before it will have insufficient remaining charge to start the vehicle. 
   As discussed above, in one aspect of the present invention, the output from the alternator  20  is adjusted based upon the state of charge and/or the state of health determination(s).  FIG. 7  is a graph showing the regulator voltage output from alternator  20  as a function of the state of charge of battery  18 . As illustrated in  FIG. 7 , microprocessor  22  reduces the voltage output from alternator  20  as the state of charge of battery  18  increases to 100% charge. The particular profile can be adjusted to a specific battery, alternator and/or engine configuration or to the driving characteristics of an operator. Such a system can significantly reduce or eliminate overcharging of battery  10  and the generation of excessive heat. Further, such a technique can be used to reduce or eliminate the undercharging of battery  10 . Additionally, by adjusting the voltage based upon the state of charge, battery  18  and system component life will increase. For example, vehicle loads  14  will be exposed to over voltages for a reduced amount of time. This also allows the various systems components to be optimized for particular charging requirements or voltage levels. In general, the output of the alternator  20  can be reduced and the battery capacity required for a particular vehicle can be reduced because battery charge will be more efficiently maintained. This can reduce overall vehicle weight and improve vehicle mileage. Further still, IR (current-resistance) type losses in the electrical system and overcharging will be reduced thereby reducing the load on the vehicle engine and improving efficiency of the vehicle. In general, this technique will improve vehicle reliability by reducing heat due to excessive IR losses, increasing battery life, providing early detection of impending battery failure and insuring proper vehicle operation even with after market batteries which are used to replace the original battery. 
   If such a system is implemented when the vehicle is originally manufactured, monitor  12  allows battery management over the entire life of the vehicle. This can be both during assembly and delivery of the vehicle as well as during the lifespan of actual vehicle operation. Additionally, one aspect includes a storage battery  18  with rating information carried in a computer storage device such as a digital memory within a housing of the battery. This data can be communicated to monitor  12  through I/O  30 . In one aspect, the electrical connections to the battery are also used as a data communication bus such that monitor  12  can communicate with the storage device in battery  18 . The storage device can also be used to store the history, such as the charging and usage history, of battery  18 . 
   Battery monitor  12  can monitor and diagnose operation of alternator  20 . For example, a typical alternator provides a multiphase output. By monitoring the data points collected and stored in memory  40 , microprocessor  22  can observe the loss of one or more phases in the alternator&#39;s output. Similarly, the failure of a rectifying diode in alternator  20  can be detected by microprocessor  22  by observing an asymmetrical ripple pattern. Microprocessor  22  can provide an output to an operator through user I/O  32  such as a “service alternator soon” output. This information can also be communicated to the vehicle microprocessor through I/O  30 . 
   I/O  30  is shown in schematic form and can be any type of input or output and represents, in some embodiments, multiple input(s) and output(s). Various examples of inputs and outputs include a connection to a databus of the vehicle, a connection to a databus adapted to couple to a diagnostic device such as that provided in service equipment, a connection to a remote vehicle monitoring system, such as one that is capable of coupling through a cellular phone connection of the vehicle. In such an embodiment, the vehicle is capable of recording and reporting information to a remote service such as an emergency assistance service or a service provided to monitor the operation of the vehicle and suggest that maintenance be provided. Various types of inputs and outputs can be provided through direct connections or through non-physical connections such as radio frequency or infrared communication techniques. The particular form of the data and standard used for the inputs and outputs can be selected as proprietary or industry standards. Microprocessor  22  can also be capable of providing advanced reporting and control functions through the use of standardized interfaces such as are available through HTML, XML, or various known or proposed alternatives. In such an embodiment, information collected by microprocessor  22  can be viewed through a “web page” interface provided by a browser. Such an embodiment is advantageous because it can provide a user input/output such as user I/O  32  in a standardized form such that it can be viewed or controlled through many types of standardized devices. In such an embodiment, information can be reported to, or the monitor  12  can be controlled, from a remote location. Additionally, if the vehicle  10  includes a browser type interface which may become commonly available in vehicles, the microprocessor  22  can be controlled and communicate through the vehicle&#39;s browser. In one aspect, vehicle monitor includes an IP (Internet Protocol) address such that it is capable of communicating in accordance with the Internet Protocol. When coupled to, for example, a cellular telephone connection of the vehicle, the battery monitor  12  is capable of being monitored and controlled from a remote location coupled through the Internet. However, as mentioned above, such an interface also provides a simple technique for interfacing the monitor  12  with a local computer in the vehicle and displaying information from the monitor  12  for use or control by an operator. 
   Through the use of the data collected by microprocessor  22  and memory  40 , microprocessor  22  is also capable of detecting the imminent failure of the starter motor of the vehicle. For example, by monitoring the voltage drop through the system during starting, microprocessor  22  can determine the average time to start the engine and the average and peak currents required during starting. Changes in these, or other, measurement values can indicate a degrading starter motor. Upon detection of an impending failure, a “service starter motor soon” indication can be provided to an operator through user interface  32 . 
   Microprocessor  22  can provide an indication that the battery  18  has insufficient capacity or substandard performance and alert an operator accordingly. For example, upon power up, such as that which occurs when battery  18  is replaced, microprocessor  22  can measure the capacity of the battery  18  and provide an indication to the operator if the capacity is less than a threshold level determined by the vehicle manufacturer and stored in the memory of the vehicle computer system. 
   Microprocessor  22  can generate an audit code (or a warranty code) in response to the various tests and data collected. Such codes are described in U.S. Pat. No. 6,051,976, issued Apr. 18, 2000, entitled METHOD AND APPARATUS FOR AUDITING A BATTERY TEST which is assigned to the present assignee and is incorporated herein by reference. In such an embodiment, microprocessor  22  encodes data collected or obtained during its operation. For example, raw data related to a battery test can be obtained and/or the ultimate result of the battery test and subsequently encoded by microprocessor  22 . The encoding can be a simple transposition cipher in which the locations and values of various bytes of information are rearranged. Such a code can be designed to prevent falsification of data which can occur where unscrupulous individuals are attempting to submit a falsified warranty claim for a failed component to a manufacturer. This coding technique allows the manufacturer to verify information when a warranty is submitted. Additionally, the information can be used to track operator error and assist in identification and isolation of component failure in order to redesign the components and reduce such failures. 
   In another aspect, microprocessor  22  is capable of automatically calibrating the measurements obtained from voltage sensor  24  and current sensor  26 . Using this aspect of the invention, microprocessor  22  can perform automatic or periodic calibrations to maintain accuracy over the lifespan of the vehicle. Automatic calibration can be provided by selectively switching in calibrated elements having known temperature and time drift characteristics, and using the measured data to correct for instrumentation gains and offsets. For example, a known resistance or voltage source can be selectively coupled to amplifiers  47  or  52 . Any offset values from these known values can be stored in memory  40  and used by microprocessor  22  to compensate for errors in measurements. 
   With the present invention, any polarization of the battery  18  such as that which can result from charging or starting operations, does not produce errors in the measurements performed by microprocessor  22 . Specifically, any such errors are eliminated by use of a real-time state of charge algorithm that is independent of the real time battery terminal voltage. 
   When the engine of vehicle  10  is not operating, microprocessor  22  can enter a sleep mode to reduce current draw and the resultant discharge of battery  18 . If desired, microprocessor  22  can periodically “wake up” to perform tests or monitor some aspect of the electrical system of vehicle  10 . 
   A loose or corroded connection to battery  18  can be detected by microprocessor  22  by observing a sudden increase in the resistance across battery  18 . An error can be provided to an operator through user interface  32  to alert the operator of the degraded connection. 
   Microprocessor  22  can also perform diagnostics on the electrical system of vehicle  12  when the engine is not operating. For example, microprocessor  22  can monitor the current being drawn by loads  14  when the engine is not running using current sensor  26 . For example, microprocessor  22  can compare the rate of current draw, over a selectable sample period with a threshold stored in memory  40 . If the measured rate exceeds the threshold, there may be a fault in the electrical system of the vehicle. Similarly, a small but constant current drain can also indicate a fault which could lead to the discharge of battery  18 . Microprocessor  22  can provide an indication to the user through user interface  32  that excessive current draw has occurred while the engine is off. Such current draw can lead to rapid discharge of battery  18  and prevent starting. 
   Current sensor  26  can also be used by microprocessor  22  to monitor the current flowing into and out of battery  18 . The summation of this current, taken over a time period (i.e., integration) can provide an indication that the battery is not receiving sufficient charge, or can provide an indication of the total charge received by battery  18 . This information can be displayed to an operator through user I/O  32 . Additionally, the information can be provided on I/O  30 . If the information indicates that the battery  18  is not receiving sufficient charge, steps can be taken as discussed above, to increase the charging rate of battery  18 . 
   In one embodiment, microprocessor  22  stores information in memory  40  related to the model number, and/or serial number, capacity or other information related to battery  18 . In such an embodiment, battery monitor  12  can be a physical part of battery  18  such that battery specific information can be programmed into memory during manufacture. The battery monitor  12  can provide an output to an operator through a display or other type of output device which is physically located on the battery  18 . Additionally, the display or user I/O  32  can be located within the vehicle. Input/output  30  can be configured to couple to the databus of the vehicle. For example, the battery  18  can include a data plug adapted to plug into the databus of the vehicle such that monitor  12  can exchange information through the databus. Microprocessor  22  can then report this information to the databus of the vehicle using input/output  30 . This allows the microprocessor of the vehicle the ability to perform advanced diagnostics and monitoring as the specific battery type is known. 
   Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, the circuitry and circuit configuration is provided as simply one embodiment and those skilled in the art will recognize that other configurations can be provided. The particular connections to the battery can be through Kelvin connections which include a “split” Kelvin connection in which the forcing function connection(s) are/is spaced apart from the battery such as that described and illustrated in U.S. patent application Ser. No. 09/431,697, filed Nov. 1, 1999 and entitled ELECTRICAL CONNECTION FOR ELECTRONIC BATTERY TESTER which is incorporated herein by reference in its entirety. In a further example of the present invention, alternator  20  can comprise an electronic battery charger such as those used to charge automotive vehicles when the vehicle is stationary or to charge stand by batteries such as those used in remote systems such as cellular sites. In such an embodiment, control line  23  is used to adjust the charger of battery  18  using the techniques set forth herein. In such an embodiment, element  10  shown in  FIG. 1  illustrates a standby power supply for equipment.