Abstract:
A method of testing a battery is provided the method may include: (a) applying a heavy load to the battery, (b) measuring the voltage V 1  between the positive and negative terminals of the battery after a first time period under which the battery is subjected to the heavy load; (c) removing the heavy load, (d) waiting for a second length of time, (e) reading the voltage across the positive and negative terminals after the second length of time V 2 , (f) performing a cold cranking amps CCA test if the CCA test indicates a CCA value above a first threshold, then consider V 2 , if V 2  is below the second threshold than skip to step g but if V 2  is above a second threshold than determine if the V 2  is above a third threshold, if V 2  is above a third threshold than determine that the battery is good and skip steps g-h; but if V 2  is below the third threshold then if a battery charge flag has been set, determine that the battery is bad and skip steps g and h, if the battery charge flag has not been set, determine that the battery is good but needs additional charging and skip steps g-h, if the CCA test indicates a CCA valve below the first threshold then move to step g, (g) determine if the battery charge flag has been set, if the battery charge flag has been set, then determine that the battery is bad, if the battery charge flag has not been set then move to step h; and (h) applying a charging current to the battery if the charging current is less than a fourth threshold amount then stop charging the battery and return to step a, if the charging current is greater than the fourth threshold amount, then charge the battery for a third length of time then stop charging the battery and return to step a.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a method and apparatus for charging a battery. More particularly, the present invention relates to a battery tester/charger for use on smaller vehicle batteries, such as batteries for all terrain vehicles (ATV&#39;s), marine batteries, motorcycle batteries and batteries for ride-on lawnmowers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Battery tester chargers are used to test a battery. Part of conducting a battery test is to load or charge the battery and then measure the voltage of the battery. Previous battery tester chargers may be used in testing and charging batteries used in vehicles such as automobiles. However, previous battery tester chargers may not provide a test tailored for use of smaller batteries used in smaller vehicles, such as motorcycles, ATV&#39;s, boats and lawnmowers. 
         [0003]    Because some prior existing battery tester chargers use a testing routine designed for larger batteries, testing and charging smaller batteries may result in a battery that is still useful for operations to fail the test and be discarded. Such a situation may result in waste of useful batteries. It may be useful to provide a battery tester charger that provides a testing and charging operation that is more appropriate for smaller batteries. 
       SUMMARY OF THE INVENTION 
       [0004]    The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus and method is provided in some embodiments provides a more appropriate testing and charging operation for batteries used in smaller vehicles. 
         [0005]    In accordance with another embodiment of the present invention, a method of testing a battery is provided. The method may include: (a) applying a heavy load to the battery, (b) measuring the voltage V 1  between the positive and negative terminals of the battery after a first time period under which the battery is subjected to the heavy load; (c) removing the heavy load, (d) waiting for a second length of time, (e) reading the voltage across the positive and negative terminals after the second length of time V 2 , (f) performing a cold cranking amps CCA test if the CCA test indicates a CCA value above a first threshold, then consider V 2 , if V 2  is below the second threshold than skip to step g but if V 2  is above a second threshold than determine if the V 2  is above a third threshold, if V 2  is above a third threshold than determine that the battery is good and skip steps g-h; but if V 2  is below the third threshold then if a battery charge flag has been set, determine that the battery is bad and skip steps g and h, if the battery charge flag has not been recently set determine that the battery is good but needs additional charging and skip steps g-h, if the CCA test indicates a CCA valve below the first threshold then move to step g, (g) determine if the battery charge flag has been set, if the battery charge flag has been set, then determine that the battery is bad, if the battery has not been charged then move to step h; and (h) applying a charging current to the battery if the charging current is less than a fourth threshold amount then stop charging the battery and return to step a, if the charging current is greater than the fourth threshold amount, then charge the battery for a third length of time then stop charging the battery and return to step a. 
         [0006]    In accordance with yet another embodiment of the present invention a battery tester charger is provided. The battery tester charger may include: a microcontroller; a data entry device operatively connected to the microcontroller; a display operatively connected to the microcontroller; and a set of terminals configured to connect the microcontroller to a battery, wherein the microcontroller is configured to; (a) applying a heavy load to the battery; (b) measuring the voltage V 1  between the positive and negative terminals of the battery after a first time period under which the battery is subjected to the heavy load; (c) removing the heavy load; (d) waiting for a second length of time; (e) reading the voltage across the positive and negative terminals after the second length of time V 2 ; (f) performing a cold cranking amps CCA test if the CCA test indicates a CCA value above a first threshold, then consider V 2 , if V 2  is below the second threshold than skip to step g but if V 2  is above a second threshold than determine if the V 2  is above a third threshold, if V 2  is above a third threshold than determine that the battery is good and skip steps g-h; but if V 2  is below the third threshold then if a battery charge flag has been set, determine that the battery is bad and skip steps g and h, if the battery charge flag has not been set determine that the battery is good but needs additional charging and skip steps g-h; if the CCA test indicates a CCA valve below the first threshold then move to step g; (g) determine if the battery charge flag has been set, if the battery charge flag has been set, then determine that the battery is bad, if the battery charge flag has not been set then move to step h; and (h) applying a charging current to the battery if the charging current is less than a fourth threshold amount then stop charging the battery and return to step a, if the charging current is greater than the fourth threshold amount, then charge the battery for a third length of time then stop charging the battery and return to step a. 
         [0007]    In accordance with another embodiment of the present invention, a battery tester charger is provided. The battery tester charger may include a means for processing; a means for entering data operatively connected to the means for processing; a means for displaying operatively connected to the means for processing; and means for connecting the means for processing to the battery, wherein the a means for processing is configured to; (a) applying a heavy load to the battery; (b) measuring the voltage V 1  between the positive and negative terminals of the battery after a first time period under which the battery is subjected to the heavy load; (c) removing the heavy load; (d) waiting for a second length of time; (e) reading the voltage across the positive and negative terminals after the second length of time V 2 ; (f) performing a cold cranking amps CCA test if the CCA test indicates a CCA value above a first threshold, then consider V 2 , if V 2  is below the second threshold than skip to step g but if V 2  is above a second threshold than determine if the V 2  is above a third threshold, if V 2  is above a third threshold than determine that the battery is good and skip steps g-h; but if V 2  is below the third threshold then if a battery charge flag has been set, determine that the battery is bad and skip steps g and h, if the battery charge flag has not been set determine that the battery is good but needs additional charging and skip steps g-h; if the CCA test indicates a CCA valve below the first threshold then move to step g; (g) determine if the battery charge flag has been set, if the battery charge flag has been set, then determine that the battery is bad, if the battery charge flag has not been set then move to step h; and (h) applying a charging current to the battery if the charging current is less than a fourth threshold amount then stop charging the battery and return to step a, if the charging current is greater than the fourth threshold amount, then charge the battery for a third length of time then stop charging the battery and return to step a. 
         [0008]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0009]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0010]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram of a battery tester charger attached to a battery in accordance with one embodiment of the invention. 
           [0012]      FIGS. 2-5  illustrate a flow chart showing a series of steps that may be accomplished by the battery charger tester in accordance with an embodiment of the invention. 
           [0013]      FIG. 6  illustrates a table showing a bounce back voltage corresponding to a cold cranking amps value. 
           [0014]      FIG. 7  is a table illustrating a maximum charge current by battery to capacity. 
           [0015]      FIG. 8  is a flow chart showing the steps accomplished during a cold cranking amp test. 
           [0016]      FIG. 9  is a flow chart showing the steps accomplished when calculating a charge time. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  illustrates a battery tester charger system  10 . A battery tester charger system  10  includes a battery tester charger  12  equipped with cables  14 . The cables  14  include a positive cable  16  and a negative cable  18 . The positive cable  16  has an alligator clamp  20  and the negative cable  18  has an alligator clamp  22 . The alligator clamps  20  and  22  have configured to attach to the positive  24  and the negative  26  post on the battery  28 . When the alligator clamps  20  and  22  are attached to the posts  24  and  26  then the battery tester charger  12  is operably connected to the battery  28 . 
         [0018]    The battery tester charger  12  includes a display screen  30  and input device  32 . The display screen  30  permits a user to see various conditions of the battery  28  as detected by the battery tester charger  12 . In addition, the display screen  30  may also display questions to which the user may input a response via the input device  32 . In some embodiments of the invention, the input device  32  may be a keyboard. In other embodiments of the invention, the input device  32  can include any device that can input data into the battery tester charger. For example, a bar code reader could be used as an input device  32 , to read a barcode on a battery  28 . The input device  32  could also not be a separate feature from the display screen  30  but may be part of the display screen  30  such as a touch screen. The input device  32  may not be a standard keyboard but may be merely various keys having functions when pressed. Any other suitable means for inputting data may be incorporated as part of the input device  32 . 
         [0019]    The tester charger  12  may be a stand alone tester charger  12  used only for smaller batteries such as those found in motorcycles, ATV&#39;s, marine applications and small lawn tractors. In other embodiments the tester charger  12  may be used with a large variety of batteries large and small. For example, the OneStep battery tester charger marketed and sold by the OTC Tool Company maybe modified or made in accordance with embodiments of the invention. The OneStep battery tester charger maybe used to recondition automotive batteries arranging in size from 150 cold cranking amps (CCA) to 1500 CCA. 
         [0020]    In some embodiments of the invention, existing battery tester chargers may be reprogrammed to conduct the steps set forth in the flow chart shown in  FIGS. 2-5 . In other embodiments of the invention existing battery tester chargers are not retrofit but rather are new battery chargers having microprocessors manufactured with software and/or hardware configured to perform the steps described in the flow chart set forth in  FIGS. 2-5 . In other embodiments the tester charger may include a computer such as a personal computer (pc). 
         [0021]    In some embodiments of the invention, the flowchart shown in  FIGS. 2-5  is a sub routine used when the battery tester charger is connected to smaller batteries such as batteries rated less than 300 CCA. Other battery testing charging routines may be used for batteries having a larger rating of 300 CCA. Other embodiments of the invention battery tester charger may only contain the routine described in  FIGS. 2-5  and batteries having a higher rating than 300 cold cranking amps use a different battery tester charger. 
         [0022]    Turning now to  FIG. 2 , the flow chart describing the steps set forth in  FIGS. 2-5  will now be described. In step S 10 , the battery tester charger  12  is turned on. Optionally the display screen  30  may display a screen showing the manufacturer of the battery tester charger and the version of the battery tester charger routine programmed onto the battery charger  12 . After a short delay, such as a two second delay for example, the battery tester charger  12  will move on to step S 12 . 
         [0023]    In step S 12  user is presented via the display screen  30  options to go and test and charge a battery or activate different functions or display a menu of functions. If the user requests the menu functions be displayed then at S 16 , the display screen  30  will display different menu features. If the user selects a “go” option to test and charge a battery, then the battery tester charger  12  will move on to step S 18  where user may be asked if the battery  28  is damaged or frozen. 
         [0024]    As shown in  FIG. 2  and step S 18 , two numbers  1  and  2  are associated next to the possible responses to the question of whether or not the battery  28  is frozen. For example, number  1  is associated with no and number  2  is associated with yes. Throughout the flow chart, shown in  FIGS. 2-5  various numbers may be associated with various responses a user may input. These numbers may be examples of buttons that a user may press to indicate a response. For example, in S 18 , pressing the button  1  on the input device  32  will indicate to the battery tester charger  12  that the no response is used. In the alternative, pressing the number  2  in the input device  32  the tester charger will take such input as a yes response to the question whether the battery  28  is damaged or frozen. However in other embodiments of the invention the user may simply type in the response or press other numbers or characters which may be associated with the various responses. The example numbers located next to and/or otherwise associated with various responses shown in  FIGS. 2-5  is meant to be exemplary only and not limiting to the invention. 
         [0025]    In some embodiments of the invention, the battery tester charger  12  may be electronically connected (either wired or wireless) to a printer to prepare and print written reports. In other embodiments in the invention, reports may be sent electronically via email or any other technique for sending electronic messages. 
         [0026]    If the user indicates that the battery  28  is frozen or damaged at step S 20  the charger  12  will indicate that the battery  28  is frozen and not usable. If the user indicates that the battery  28  is not frozen, then the system may advance to S 22  where the user may enter a part number for the battery  28 . If the user does indicate that a part number is desired to be entered then at step S 24  the part number entry process is initiated. At step S 28 , the battery tester charger  12  asks the user if the battery  28  has a part number. If it does not, the system moves to S 26  where a user may enter what type of battery rating  28  is to be used. 
         [0027]    However, if the battery  28  does have a part number, then at step S 32  if the part number has a rated CCA or cold cranking amps associated with it as programmed into a memory associated with a micro controller, then the system may automatically advance to step S 44 . However, if there is no CCA associated with the part number as stored on the tester charger  12  then the user will be prompted to enter the rated CCA associated with the battery  28  or part number. 
         [0028]    Once the user has associated the rated CCA associated with the battery  28 , then the system will continue to step S 44 . In some embodiments of the invention the user may need to press go or a similar input in order for the battery tester charger  12  to advance to the next step. 
         [0029]    Returning now to step S 22 , if the user indicated that there was no part number associated with the battery  28  or did not wish to enter one, then the system would advance to step S 26 . The user would be asked to select-what type of battery  28  rating to be used for the test. Once the rating type had been entered in step S 30 , then the battery tester charger  12  may ask the user if the battery  28  to be tested and charged is a gel cell battery, an absorbed glass mat (AGM) battery or a spiral wound battery, (such as one commonly identified as an Optima battery). 
         [0030]    If the answer to these questions is no, then the system assumes that the battery  28  to be tested is a flooded lead acid battery FLA. Once the user has indicated whether or not the battery is a gel, AGM or spiral wound battery in step S 35 , at step S 38  the system will ask user whether the battery  28  is rated for less than 300 CCA. If the battery  28  is not rated for greater than 300 CCA battery tester charger  12  will move to A at step S 40  on  FIG. 3 . 
         [0031]    If the battery is rated at greater than 300 cold cranking amps then the user may be prompted to respond to whether the battery  28  is large sized, for example, 3D, 4D,  31 , etc. The user may then be asked at S 38  if the battery is rated for greater than 300 CCA&#39;s. If the answer is no, then at step S 40 , the system will move to A on  FIG. 3 . If the answer is yes, then at step S 14  the tester charger  12  will not enter the small battery charging and testing, routine described herein and go to a large battery tester charging routine. 
         [0032]    It will be understood that the entry data requested in the routine described in  FIG. 2  are optional questions. In some embodiments of the invention, the battery tester charger  12  may sense what type of battery  28  is being tested or charged. In other embodiments of the invention fewer or more questions than those set forth in the steps described in  FIG. 2  may be used in accordance with the invention. 
         [0033]    Now turning to  FIG. 3  at A, the next step shown is step S 46 . At S 46  a heavy load is applied to the battery  28  for about 4 seconds. In some embodiments of the invention, the heavy load is about 150 amps. At step S 48 , after applying the heavy load for about 4 seconds, the battery tester charger  12  senses the voltage between the positive  24  and the negative  26  posts. After the load volts have been sensed and recorded by a battery tester charger at step S 50  the heavy load is turned off. At step S 52 , the battery charger tester  12  waits a first period of time for the battery  28  to recover from the heavy load. In some embodiments of the invention, that waiting time may be about 20 seconds. 
         [0034]    At step S 54  a battery tester charger may then read the voltage between the positive posts  24  and the negative post  26  as a recovery voltage. This recovery voltage is illustrated in  FIG. 3  and is referred to as rv20sb meaning recovery voltage at 20 seconds for a small battery. At step S 56 , the battery tester charger  12  may calculate a charge time based on the recovery voltage. 
         [0035]    It will be understood that some embodiments of the invention the steps listed in  FIG. 3  may be accomplished more than once as part of the loop during a battery testing charging procedure. However, step S 56  in some embodiments of the invention is only accomplished the first time steps shown in  FIG. 3  are accomplished during a single battery charging and testing session. In other words, if the steps shown in  FIG. 3  are repeated multiple times during a battery charging session, step S 56  is accomplished only the first time and omitted in other loops involving the steps shown in  FIG. 3 . 
         [0036]    At step S 58 , if the battery  28  was inputted back at step S 34  to be a gel, AGM or spinal wound battery then the system would move to step S 64 . However if at step S 58 , the user did not input that the battery was a gel, AGM or spiral wound battery, then the system would move to step S 60  where the system would determine whether the recovery voltage read at step S 54  was less than 11 volts. If the recovery voltage was not less than 11 volts, then the system would move to step S 64 , which is to go to B on  FIG. 4 . If the recovery voltage as measured in step S 54  was less than 11 volts then the system would move to step S 62 . At step S 62  the tester  12  determines if the 4 second load voltage as read at step S 48  was greater than 3.5 volts. If it was not, then the system would move to step S 64 . However, if the 4 second load voltage as recorded in step S 48  was greater than 3.5 volts then the system determines the battery to be bad and the system moves to S 68  where the display  30  indicates the battery  28  is bad and a printed report at S 66  maybe generated indicating that the battery  28  is bad. 
         [0037]    As an alternative to printing a report, an electronic report may be sent via email or any other way of transmitting electronic data indicating that the battery  28  is bad. When a printed report is generated as indicated in S 66 , two copies of the report may be made. One report may be prepared for the customer and one for the technician. Once the battery  28  is determined to be bad, the routine is then stopped. Then at step S 68  a user may input data via the input device  32  to start the process over with a new battery or to conduct some other function. 
         [0038]    If the battery  28  is not indicated to be bad, the system moves to part B shown in  FIG. 4 . As step S 70  the system performs a cold cranking amps CCA test at step S 70 . The CCA test at S 70  is shown at  FIG. 8 . The CCA test at S 70  includes turning on a micro load at S 70 A. The micro load may be 25.2 amps. Other values may also be used. At step S 70   b  the system waits for a period of time, for example, 500 milliseconds. At step S 70   c  the system reads the micro load volts V 1 . At step S 70   d  the system turns off the micro load and waits for a period of time. As listed in step  70   e  in some embodiments the invention, the period of time may be about 2 seconds. At step S 70   f , the system may read the micro load volts V 2  which is the voltage of the battery after the waiting period. At step S 70   g  the bounce back voltage may be calculated which is V 2  minus V 1 . In other words, the micro load volts V 2  measured after the micro load has been removed minus the micro load voltage when this battery was under a micro load. The bounce back voltage maybe indicated by Vbb in the figures attached. At step S 70   h , the system may calculate a tested capacity and return that capacity at step S 70   i.    
         [0039]    At step S 72 , the tested calculated capacity is considered the system makes a determination based on whether the tested calculated capacity determined at step S 70   h  is greater than 75% of the rated cold cranking amps of the battery. S 74  shows an example look up table that may be programmed or saved into the battery tester charger  12  to make this determination. For example, in an example embodiment if the tested and calculated CCA is greater than 7 volts for a battery rated for a 150-199 CCA the testing CCA will be greater than 75% of the rating CCA. If the tested or measured CCA is greater than 7.8 volts for a 200-249 rated CCA battery, the tested or measured CCA will be greater than 75% of the rated CCA. If the measured tested CCA is greater than 8.6 volts for a 250-300 CCA rated battery then the tested or measured CCA will be greater then 75% of the rated CCA. 
         [0040]    If the tested CCA is greater than 75% of the rated cold cranking amps then the system, moves to step S 78  where the recovery voltage calculated at step S 54  is compared against a threshold amount of 12.1 volts. If the recovery voltage is less than 12.1 volts then the system moves to step S 76 . However, if the recovery voltage is greater than 12.1 volts the system moves to S 80  and a second threshold value is compared against the recovery voltage. If the recovery voltage is greater than 12.3 volts then it is determined that the battery is good at step S 83  and a printed report may be generated at step S 66 . Again the report may be printed electronically or on paper and multiple copies of the report may be generated. 
         [0041]    However, if the recovery voltage is not greater than 12.3 volts then the system may move to part C shown in  FIG. 5  as illustrated in step S 82 . 
         [0042]    Returning to step S 78 , if the voltage is not greater than 12.1 volts then the system returns to step S 76 . In addition, at step S 72  if the tested CCA is not greater than 75% of the rated cold cranking amp then the system also moves to step S 76 . At step S 76  the system determines whether or not a battery  28  charge flag has been set. In some embodiments, a charge flag or other marker is set to indicate that the battery  28  has been charged during the current test/charge procedure. If the charge flag has been set (indicating the battery  28  was charged during the test charge cycle) then at step S 68 , the system will display that the battery  28  is bad and print reports or generate electronic reports at step S 66 . However, if at step S 76  it is determined that that no charge flag has been set, then at step S 84 , the battery tester charger  12  will start to charge the battery  28 . 
         [0043]    In some embodiments where the method shown as the steps illustrated in  FIGS. 2-5  is incorporated into a tester charger  12  that also tests and charges large batteries. 
         [0044]    As shown in step S 84  the test recharger  12  starts to charge the battery  28 . As indicated in step S 86 , if the charge time is less than 10 minutes then the charging routine will continue. Once the charge time reaches 10 minutes as indicated in step S 88  then as indicated in step S 90  and S 94 , the charging function will be turned off. 
         [0045]    At that point, the charger tester  12  will go to A on  FIG. 3  as indicated in S 40 . However, returning to step S 86 , while the charge time is less than 10 minutes the tester charger  12  will not be monitoring the charge amps in step S 92 . If the charge time is greater than 10 minutes, and if the charge amps are less than a certain threshold, for example three amps, then as indicated in step S 96  the charger tester  12  will turn off the charge and set the charge done flag in step S 96 . However, if the charging amps do exceed the threshold and the charge time is not complete then the charging will continue as indicated in steps S 92  and S 94 . 
         [0046]    Once the charge time is completed as indicated in step S 88  or in S 94  then as indicated in step S 90  and S 94  the charge will turned off and the charge flag will be set. The battery tester charger will move to A in  FIG. 3  as indicated in step S 40 . 
         [0047]    Turning to step S 82 , when the system moves to C as indicated in  FIG. 5  to step S 98 . The charger tester  12  in step S 98  determines whether the battery  28  has been set. If the battery  28  charge flag has been set as indicated then at S 68  the tester charger  12  will display the battery  28  is bad and will print a report accordingly as indicated in S 66 . 
         [0048]    However, if it is determined that the battery  28  charge flag is not set in step S 98  then the battery tester charger  12  will determine at step S 100  that the battery  28  is good but needs more charge. 
         [0049]    Depending upon the value for the recovery voltage, an estimated charge time will be calculated in step S 56 .  FIG. 9  shows a listing of example steps that may be taken to calculated an estimated charge time. Starting in S 110  the charge time is considered to be Tc. In S 112 , the battery voltage (shown in  FIG. 9  as Iv_ 4 ) is compared. If Iv_ 4  is less than 4 volts, that in S 114  the charge time will be calculated to be 60 minutes. If Iv_ 4  is not less than 4 volts, than in S 116  rv20 is compared with 11.7 and 12.5 volts. If rv20 is greater than 11.7 and less than 12.5 volts, than at step  118 , the valve for Vss is assigned the valve of rv20. 
         [0050]    However, if rv20 is not greater than 11.7 and less than 12.5 volts, than at S 120  rv20 is compared to determine if rv20 is less than 11.7 volts. If rv20 less than 11.7 volts than the valve for Vss is assigned 11.7. If rv20 is not less than 11.7 volts than in S 124 , the value for Vss is assigned the value of 12.5. Once a value for Vss is assigned in either steps S 118 , S 122  or S 124 , in S 126  the assigned value for Vss is subtracted from 12.5 and that number is multiplied by 58.5 for a 20 amp input unit or the number is multiplied by 78.125 for a 15 amp unit. 
         [0051]    The number arrived at in S 126  is compared to 60 in S 132 . If the number from S 128  is greater than 60 then in S 134  the estimated charge time is 60 minutes. If the number from S 128  is less than 60 than in S 136  the charge time is number arrived at in S 128  in minutes. 
         [0052]    Returning now to  FIG. 5 , in step S 100  the display screen  30  may indicate to a user that the battery  28  is good but the battery  28  needs more charging and may indicate an estimated charge time. Estimating the amount of time it will take to charge the battery in S 100  may be accomplished by using the calculation arrived at in S 56 . After the remaining charge time has been displayed on the screen  30  for a period of time (for example perhaps 2 seconds), then the battery tester charger  12  will request that the user indicate whether the user wishes more charging to occur in step S 102 . 
         [0053]    As indicated in step S 104 , if a certain time period elapses (for example 60 seconds) and the user has not responded, then charging will occur automatically. As indicated in Step S 104 , if the user does not want to continue, a report will be generated that the battery  28  is good but more charging is needed in step S 66 . If a user determines that they do wish to continue to charge the battery  28  then the system will go to part B on  FIG. 4  as indicated in step S 64  in  FIG. 5 . 
         [0054]      FIG. 7  indicates a maximum charge current that may be used depending on the rated CCA in the battery. For example, if a battery is rated between 250 and 300 CCA then a maximum of 30 amps would be used to change the battery. If the rated CCA is between 200 and 249 then the maximum charging current will be 25 amps. If the rated CCA is between 150 and 199 then the maximum charge current will be 20 amps. 
         [0055]      FIG. 6  is a chart indicating a bounce back voltage (Vbb) times  100  value having a corresponded tested CCA value. The charger tester  12  may have a look up table stored in its memory to search for a CCA corresponding to a Vbb once the Vbb is determined a corresponding CCA and be returned via the look up table and used during the CCA test at step S 70 . For values in between values shown on the table of  FIG. 6  a CCA may be interpolated from the table. 
         [0056]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.