Battery pack maintenance for electric vehicle

Abstract

A method and apparatus for repairing or testing a used battery pack from an electric vehicle include removing the battery pack from the vehicle. Battery tests are performed on at least some of the plurality of batteries and battery test results for each of the batteries tested are obtained. A cradle is configured to receive at least two different types of batteries. The cradle includes connectors to electrically couple circuitry of a battery tester to the battery.

Description

BACKGROUND OF THE INVENTION

The present invention relates to electric vehicles of the types which use battery packs for storing electricity. More specifically, the present invention relates to maintenance of such battery packs.

Traditionally, automotive vehicles have used internal combustion engines as their power source. Petroleum as a source of power. However, vehicles which also store energy in batteries are finding widespread use. Such vehicle can provide increased fuel efficiency and can be operated using alternative energy sources.

Some types of electric vehicles are completely powered using electric motors and electricity. Other types of electric vehicles include an internal combustion engine. The internal combustion engine can be used to generate electricity and supplement the power delivered by the electric motor. These types of vehicles are known as “hybrid” electric vehicles.

Operation of an electric vehicle requires a source of electricity. Typically, electric vehicles store electricity in large battery packs which consist of a plurality of batteries. These batteries may be formed by a number of individual cells or may themselves be individual cells depending on the configuration of the battery and battery pack. The packs are large and replacement can be expensive.

SUMMARY OF THE INVENTION

A method and apparatus for repairing or testing a used battery pack from an electric vehicle include removing the battery pack from the vehicle. Battery tests are performed on at least some of the plurality of batteries and battery test results for each of the batteries tested are obtained. A cradle is configured to receive at least two different types of batteries. The cradle includes connectors to electrically couple circuitry of a battery tester to the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an electric vehicle.

FIG. 2 is simplified schematic diagram of a battery pack for use in the electric vehicle of FIG. 1.

FIG. 3 is a block diagram of a device in accordance with one example embodiment of the present invention.

FIG. 4 is a simplified block diagram of a device for use in selecting batteries for use in refurbishing a battery pack.

FIG. 5 illustrates a database shown in FIGS. 3 and 4.

FIG. 6 is a flow chart showing steps for use in refurbishing a battery pack.

FIG. 7 is a simplified block diagram showing a diagnostic device including a cradle configured to receive battery.

FIG. 8 shows graphs of voltage and current versus time charging of a battery.

FIG. 9 shows graphs of voltage and current versus discharging of a battery.

FIG. 10 is a front perspective view of a configuration of an electric vehicle battery.

FIG. 11 is front perspective view of another configuration of an electric vehicle battery.

FIG. 12A is a front perspective view and FIG. 12B is a rear perspective view of a configuration of a hybrid electric vehicle battery.

FIG. 13A is a front perspective view and FIG. 13B is a rear perspective view of a another configuration of a hybrid electric vehicle battery.

FIG. 14 is a schematic diagram showing polarity reversing circuitry for use in coupling to a battery.

FIG. 15 is a perspective view showing electric vehicle battery encased in a cradle.

FIG. 16 is a perspective view showing a battery of FIG. 15 placed into the cradle.

FIG. 17 is a perspective view showing a battery of FIG. 16 placed into the cradle.

FIG. 18 is a perspective showing a cradle with a cover in the closed position.

FIG. 19 is a top cutaway view of the cradle of FIG. 15.

FIG. 20 is a perspective view of a hybrid electric vehicle battery facing a cradle.

FIG. 21 is a perspective view of a battery positioned in the cradle of FIG. 20.

FIG. 22 is a perspective view of a battery secured in the cradle of FIG. 20.

FIG. 23 is a perspective view showing the cradle of FIG. 20 having a cover in the closed position.

FIG. 24 is a side cross sectional view of the cradle of FIG. 20.

FIG. 25 is a perspective view showing an electrical contacts of FIG. 20.

FIG. 26 is a top plan view of the battery placed in a cradle of FIG. 20.

FIG. 27 is a top plan view showing the battery secured in the cradle of FIG. 20.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As discussed in the background section, battery packs used with electric vehicles are able to store large amounts of energy. The battery packs are large and difficult to work on and test because of the high voltages involved. Further, the battery packs are expensive. In one aspect, the present application recognizes that a single bad battery within the battery pack can reduce the capabilities of the overall battery pack. A bad battery or (batteries) can reduce the amount of energy the battery pack can store, reduce the rate at which the battery pack can be recharged and cause other batteries with in the battery pack to drain prematurely.

In one aspect of the present invention, a battery pack is removed from the electric vehicle whereby maintenance can be performed on it. More specifically, individual batteries of the pack tested. A refurbished battery pack is made by preparing a new set of batteries for use in creating a refurbished battery pack. The new set of batteries is formed from used batteries from previously used battery pack(s) along with one or more additional batteries. The set of batteries used to form the refurbished battery pack are selected such that they have at least one test result which is similar to the others. The refurbished battery pack can then placed in an electric vehicle and be used as a source of power for the vehicle.

FIG. 1 is a simplified block diagram of an electric vehicle 100. Electric vehicle 100 can be configured to operate solely based upon electric power, or may include an internal combustion engine. Vehicle 100 includes a battery pack 102 and at least one electric motor 104. Vehicle electronics and control system 106 couples to the battery pack and electric motor and is configured to control their operation. Wheels 110 of vehicle 100 are configured to propel the vehicle in response to a mechanical input from electric motor 104. Electric motor 104 operates using energy drawn from the battery 102. In some configurations a regenerative braking system can be used in which a braking energy is recovered from the wheels 110 by the electric motor 104 or other equipment. The recovered energy can be used to recharge the battery pack 102.

FIG. 1 also shows optional components of vehicle 100. These optional components allow the vehicle 100 to operate as “hybrid” vehicle. In such a configuration, an internal combustion engine 120 is provided which operates using, for example, petroleum based fuel 122. The engine 120 can be configured to directly mechanically drive the wheels 110 and/or an electric generator 122. The electric generator 122 can be configured to charge the battery pack 102 and/or provide electrical power directly to electric motor 104.

The battery pack 102 is a critical component of the electric vehicle 100. Operation of the battery pack 102 will determine the efficiency of the vehicle, the overall range of the vehicle, the rate at which the battery pack 102 can be charged and the rate at which the battery pack 102 can be discharged.

FIG. 2 is a simplified diagram of an example configuration of battery pack 102. In FIG. 2, a plurality of individual batteries 140 are shown connected in series and parallel. Each of the individual batteries 140 may comprise a single cell or may comprise multiple cells connected in series and/or parallel. These may be removable battery modules formed by a single cell or a group of cells. If elements 140 are a group of cells, in some configurations individual connections may be available within the battery and used in accordance with the invention.

During the lifetime of vehicle 100, the battery pack 102 will degrade with time and use. This degradation may be gradual, or may occur rapidly based upon a failure of a component within the pack 102. When such a failure occurs, or when the pack has degraded sufficiently, the entire battery pack 102 is typically replaced. The battery pack 102 is one of the primary components of electric vehicle 100 and its replacement can be very expensive. In one aspect, the present invention is directed to performing maintenance on battery pack 102. The maintenance can be performed after the battery pack has failed, or prior to the failure of the battery pack.

In one aspect, the invention includes the recognition that the failure, degradation, or impending failure of battery pack 102 may be due to the failing or degrading of one or more of the individual batteries 140 within the pack 102. In such a case, the battery pack 102 can be refurbished or otherwise repaired by identifying the failed, failing, or degraded batteries 140 and replacing them with operable batteries 140. In another aspect, the present invention includes the recognition that the simple replacement of a faulty battery 140 in a battery pack 102 may not provide the optimum configuration for the repaired or refurbished battery pack 102. More specifically, a “new” battery 140 used to replace a “bad” battery 140 within the battery pack 102 will introduce a battery which is not balanced with respect to other batteries 140 in the pack 102. This unbalanced battery 140 may cause further deterioration in the battery pack 102. Thus, in one aspect, the present invention includes selecting batteries 140 which have a similar characteristic or measured parameter for replacing bad batteries 140 within a battery pack 102.

In one aspect, the present invention provides a method and apparatus in which batteries 140 for use in battery packs 102 are sorted and selected for replacement based upon measured parameters. The measured parameters can be selected such that they are in agreement with one another within a desired range. Example parameters include static parameters in which a static property of a battery is measured using a static function as well as dynamic parameters in which a property of a battery is measured using a dynamic function. Example parameters include dynamic parameters such as conductance resistance, admittance, impedance, etc., as well as static equivalents. Load testing based parameters may also be employed. Other example parameters include battery capacitance, battery state of charge, battery voltage, and others.

FIG. 3 is a simplified block diagram of a battery pack maintenance device 200 for performing maintenance on battery pack 102. FIG. 3 shows one example of battery test circuitry, in FIG. 3 maintenance device 200 is shown coupled to battery 140 having a positive terminal 202 and a negative terminal 204. A connection 206 is provided to terminal 202 and a similar connector 208 is provided to terminal 204. The connectors 204 and 206 are illustrated as Kelvin connectors, however, the invention is not limited to this configuration. Through connections 206 and 208, a forcing function 210 is coupled to battery 140. The forcing function applies a forcing function signal to the battery 140. The forcing function signal may have a time varying component and may be an active signal in which an electrical signal is injected into the battery or maybe a passive signal in which a current is drawn from the battery. Measurement circuitry 212 is configured to measure a response to the battery 140 to the applied forcing function signal from the forcing function 210. Measurement circuitry 212 provides a measurement signal to microprocessor 214. Microprocessor 214 operates in accordance with instructions stored in memory 220. Memory 220 may also be configured to contain parameters measured from battery 140. A user input/output circuitry 220 is provided for use by an operator. Further, the device 200 is configured to store data in database 220. The battery testing may be optionally performed in accordance with techniques pioneered by Midtronics, Inc. of Willowbrook, Ill., and Dr. Keith S. Champlin, including for example, those discussed in U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin; U.S. Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin; U.S. Pat. No. 4,816,768, issued Mar. 28, 1989, to Champlin; U.S. Pat. No. 4,825,170, issued Apr. 25, 1989, to Champlin; U.S. Pat. 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No. 11/931,907, filed Oct. 31, 2007, entitled BATTERY MAINTENANCE WITH PROBE LIGHT; U.S. Ser. No. 60/992,798, filed Dec. 6, 2007, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 61/061,848, filed Jun. 16, 2008, entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/168,264, filed Jul. 7, 2008, entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No. 12/174,894, filed Jul. 17, 2008, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 12/204,141, filed Sep. 4, 2008, entitled ELECTRONIC BATTERY TESTER OR CHARGER WITH DATABUS CONNECTION; U.S. Ser. No. 12/328,022, filed Dec. 4, 2008, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 12/416,457, filed Apr. 1, 2009, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION; U.S. Ser. No. 12/416,453, filed Apr. 1, 2009, entitled INTEGRATED TAG READER AND ENVIRONMENT SENSOR; U.S. Ser. No. 12/416,445, filed Apr. 1, 2009, entitled SIMPLIFICATION OF INVENTORY MANAGEMENT; U.S. Ser. No. 12/485,459, filed Jun. 16, 2009, entitled CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/498,642, filed Jul. 7, 2009, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/697,485, filed Feb. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/698,375, filed Feb. 2, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/712,456, filed Feb. 25, 2010, entitled METHOD AND APPARATU FOR DETECTING CELL DETERIORATION IN AN ELECTROCHEMICAL CELL OR BATTERY; U.S. Ser. No. 61/311,485, filed Mar. 8, 2010, entitled BATTERY TESTER WITH DATABUS FOR COMMUNICATING WITH VEHICLE ELECTRICAL SYSTEM; U.S. Ser. No. 61/313,893, filed Mar. 15, 2010, entitled USE OF BATTERY MANUFACTURE/SELL DATE IN DIAGNOSIS AND RECOVERY OF DISCHARGED BATTERIES; U.S. Ser. No. 12/758,407, filed Apr. 12, 2010, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 12/765,323, filed Apr. 22, 2010, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 12/769,911, filed Apr. 29, 2010, entitled STATIONARY BATTERY TESTER; U.S. Ser. No. 61/330,497, filed May 3, 2010, entitled MAGIC WAND WITH ADVANCED HARNESS DETECTION; U.S. Ser. No. 12/774,892, filed May 6, 2010, entitled SCAN TOOL FOR ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/786,890, filed May 25, 2010, entitled BATTERY TESTER WITH PROMOTION FEATURE; U.S. Ser. No. 61/348,901, filed May 27, 2010, entitled ELECTRTONIC BATTERY TESTER; U.S. Ser. No. 29/362,827, filed Jun. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 61/351,017, filed Jun. 3, 2010, entitled IMPROVED ELECTRIC VEHICLE AND HYBRID ELECTRIC VEHICLE BATTERY MODULE BALANCER; U.S. Ser. No. 12/818,290, filed Jun. 18, 2010, entitled BATTERY MAINTENANCE DEVICE WITH THERMAL BUFFER; U.S. Ser. No. 61/373,045, filed Aug. 12, 2010, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONERY STORAGE BATTERY; U.S. Ser. No. 12/888,689, filed Sep. 23, 2010, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 12/894,951, filed Sep. 30, 2010, entitled BATTERY PACK MAINTENANCE FOR ELECTRIC VEHICLES; U.S. Ser. No. 61/411,162, filed Nov. 8, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 13/037,641, filed Mar. 1, 2011, entitled MONITOR FOR FRONT TERMINAL BATTERIES; which are incorporated herein by reference in their entirety.

During operation, device 200 is capable of measuring a parameter of battery 140 through the Kelvin connections 206 and 208. For example, a forcing function can be applied by forcing function 210. Measurement circuitry 212 can monitor the effect of the applied forcing function signal on the battery 140 and responsively provide an output to microprocessor 214. This can be used to measure a dynamic parameter of the battery such as dynamic conductance, etc. The present invention is not limited to this particular testing method and other techniques may also be employed. Further, the testing of battery 140 or group of batteries 140 may be performed using sensors within battery pack 102. In such a configuration, the testing may be performed without disassembling the battery pack 102. Microprocessor 214 can operate in accordance with programming instructions stored in memory 220. Memory 220 can also store information by microprocessor 214. Operation of device 200 can be controlled by user I/O 220 which can comprise, for example, a manual input such as a keyboard and/or an output such as a display. As discussed below in greater detail, measured parameters of battery can be stored in database 222 for subsequent retrieval.

FIG. 4 is simplified block diagram of a battery selection system 250 in accordance with one example embodiment of the invention. Battery selection system 250 can be embodied in the device 200 shown in FIG. 3 or can be a separate system. System 250 may typically be implemented in a computer or microprocessor system and is configured to access information from the database 222. System 250 includes a controller 252 coupled to the database 222 and battery selection criteria 254. Controller 252 examines battery parameters stored in database 222 based upon the selection criteria 254. Based upon this examination, controller 252 provides a selection information output 255. The selection information output 255 provides information related to which of the batteries identified in the database 222 should be used to form a refurbished battery pack 102. The selection information output 255 may also include information related to specifically where in the physical or electrical configuration of the battery pack 102 a specific battery 140 should be positioned. A user I/O 256 is also provided which may include a physical input such as a keypad and/or an output such as a display. The user I/O can be used to provide instructions to controller 252 and provide a mechanism for controller 252 to provide an output to an operator. The selection information 255 output may be delivered through the user I/O 256 or through some other means. Further, the selection criteria 254 can be updated as desired. In some configurations, controller 252 can also be configured to modify data within the database 222. The selection criteria 254 and the database 222 can be implemented in a memory such as memory 220 shown in FIG. 3.

FIG. 5 shows an example configuration of database 222. Database 222 includes a number of different fields. A battery identification field 224 is used to store information which identifies a battery 140. The battery 140 may be a battery from within an existing battery pack 102 or may be a new battery 140. At least one battery parameter 226 is associated with an identified battery. In some configurations, more than one battery parameter 226 is associated with one specific battery 140.

The battery identification 224 can be in accordance with any technique which will provide information which can be used to identify a battery. This may include, for example, a serial number or the like. The identifying information can be created during the refurbishing process, or at some other time, for example, during manufacture of a battery 140 or pack 102. This information may be manually entered into the database 222 using, for example, user I/O 220 shown in FIG. 3 or user I/O 256 shown in FIG. 4, or may be entered into database 222 using more automated techniques such as a barcode scanner, RFID tag, etc. User I/O 220 and 256 may comprise such inputs. The battery parameter 226 can comprise any information which is related to an identified battery 140. The information can be information obtained through a battery test or may be information obtained through other means. For example, information related to the age of the battery may be used, information related to whether the battery 140 came from a battery pack 102 in which an operator has or has not identified any problems, manufacturing information, geographic location information, information related to a location of a battery within the battery pack 102, etc. Examples of other parameters include parameters collected by testing the battery may include temperature, etc. These parameters may include the results of any type of battery test or data measured or collected prior to, during, or after a test is performed and are not limited to those discussed herein.

FIG. 6 is simplified block diagram 300 shown in steps in accordance with one example embodiment of the present invention. The steps begin at start block 302. At block 304 battery parameters are collected as discussed above. These battery parameters are stored in the database 222 and associated with information which identifies a respective battery 140. At block 306, the selection criteria 254 is applied to the data contained in database 222. Based upon this selection criteria, at block 308, the controller 352 shown in FIG. 4 provides the selection information output 255 which identifies refurbished battery pack information as discussed above.

During operation of the system discussed above, any bad batteries 140 within the battery pack 102 are identified by testing and removed from the battery pack. This may require that the battery pack 102 be charged and discharged. Further, remaining batteries 140 in the battery pack 102, as well as any replacement batteries 140, may be charged or discharged such that they are all at the approximately the same state of charge.

The batteries may be tested while remaining in the pack through connections at individual points between multiple batteries. In another example, the batteries are tested by collecting data over an internal databus of vehicle 100 using techniques described in copending application Ser. No. 12/174,894 which is entitled BATTERY TESTER FOR ELECTRIC VEHICLE, filed Jul. 17, 2008. In another example, the entire battery pack 102 may be tested by supplying a known current to the entire pack 102, or a portion of the pack 102. This current may be a DC current, a time varying DC current, a bi-polar current, a uni-polar AC current, etc. While is current is applied, a battery 140 or groups of batteries 140 within the battery pack 102 can be monitored. This monitoring may be through sensors which are internal to the battery pack 102 or through sensors which are separably applied to the battery 102. In another example, individual batteries are removed from the pack and tested.

The present invention includes the recognition that in a high voltage string of batteries, simply replacing one faulty battery 140 with a new battery 140 may not provide an optimal solution in refurbishing the battery pack 102. This is because the replacement battery 140 may be out of balance with the other batteries 140 in the battery pack 102. Thus, it is desirable that the batteries 140 in the battery pack 102 be balanced in such a way that they have a similar capacity, state of charge, voltage, impedance, conductance, or other parameter, depending upon the selection criteria 254.

The particular selection criteria 254 can be selected as desired. For example, the selection criteria 254 can be determined by testing many batteries 140 across many different battery packs 102 and identifying which parameter 226 or parameters 226 will have a detrimental impact if they are “out of balance” with other batteries 140 within a battery pack 102, identifying a range of acceptable values of a particular parameter 226, identifying an interrelationship between multiple parameters 226 and/or identifying a particular physical or electrical configuration of such batteries 140 within a battery pack 102. Using a load test as an example, a group of batteries 140 may be fully charged and then discharged for a period of time at a desired discharged rate. The voltage of the batteries 140 during or following the discharge can be measured. Batteries 140 having a voltage which is within a selected percentage of the voltage of other batteries 140 may be identified for use in a refurbished battery pack 102. This selection process may be applied only to batteries 140 which are used to replace faulty batteries 140 within a battery pack 102, or may be applied to additional batteries 140 within the battery pack 102 including all of the batteries 140 within a particular battery pack 102. Further, the batteries 140 which are used to replace faulty batteries 140 may themselves be retrieved from other battery packs 102 which are in the process of being refurbished or otherwise disassembled. The replacement batteries 140 may also comprise new or otherwise unused batteries 140. The battery 140 discussed herein may comprise an individual cell or may comprise multiple cells or batteries. The battery 140 and/or cells may operate in accordance with any suitable battery technology. The database 222 discussed above may be implemented in any suitable database 222 format. In one configuration, the database 222 may be implemented manually. In another configuration, the database is stored in a memory, for example, a computer memory.

FIG. 7 is a simplified block diagram showing battery tester 200 including a battery cradle 350. Tester 200 includes test circuitry 352 coupled to user I/O 220. FIG. 7 also illustrates a remote I/O connection 354 for communicating with a remote location such as over a network, to a centralized data system, to other electrical equipment, to a remote user, etc. An optional printer 356 is also illustrated in FIG. 7 and can be used to provide a physical hard copy of test results or other information.

The test circuitry 352 couples to the battery 350 to a removable cable 360. Cable 360 has ends 362 and 364 which plug into the battery cradle 350 and the test circuitry 352, respectively. The battery 140 can be placed into the cradle 350 whereby tests may be performed by the battery 140. Battery 140 is illustrated as including battery terminals 202 and 204 which couple to Kelvin connections 206 and 208 in cradle 350. These may be Kelvin connections or single connections. A midpoint connector 370 is also illustrated which allows a midpoint test connector 372 to connect to one or more connections between cells or groups of cells within the battery 140.

The configuration shown in FIG. 7 simplifies the technical requirements of connecting a battery to the battery test circuitry. The use of an individual cradle allows the battery to simply be “snapped” into place for testing. The cradle can include a protective case cover and integrated safety lock to protect the operator and circuitry during testing. Mechanical and/or electrical polarity detection can be used as discussed below in greater detail. The cable 360 can be replaceable as if it becomes worn through extended use. Additionally, different types of cradles can be used for different types of batteries 140 and simply plugged into the cable 360. Some particular types of cradles 350 may use different types of cabling connections 360. This allows the particular cable to be easily exchanged and/or plugged into a different type of cradle 350. In one configuration, the cable 360 represents a wireless communication link such as an RF link using BlueTooth®, WIFI, etc. In such a configuration, part of the test circuitry maybe located within the cradle 350 in order to sense voltages directed and/or apply forcing functions. The remote I/O 354 can then communicate as appropriate including wireless or wired connections such as Ethernet, WIFI, etc. The battery test circuitry 352 can be configured for testing, discharging and charging the battery 140. Some tests or battery maintenance may require discharging or recharging as well as testing the battery 140.

In one configuration, the test circuitry 352 receives information regarding the state of charge and/or voltage of batteries within a battery pack. A replacement battery 140 is then connected to the device 200 and the circuitry 352 adjust the state of charge and/or voltage of the replacement battery 140 to more closely match the state of charge and/or the voltage of the other batteries within the pack. As specified above, similar techniques can be used to balance the state of charge for all the batteries within a battery pack. The information regarding the state of charge and/or voltage can be received by the test circuitry by a user I/O 220 or through remote I/O 354. For example, the information may be received from the onboard databus of the vehicle such as OBDII databus, over wireless connection, input by service personnel. The state of charge of the battery may be determined using an approximate relationship between voltage of the battery, and/or current in/out of the battery, and state of charge. Other techniques may be used including measurement of dynamic parameter as discussed above. When charging a battery, the circuitry can be charged using a constant current or can charge in a constant current or constant voltage mode as desired. In such embodiments, the forcing function 210 is configured as a constant current source, a constant voltage source as well as a load including a constant current load.

Preferably, the test circuitry includes a fail safe configuration whereby if a voltage of a battery is out of a predetermined range, such as 2.5 volts to 4.25 volts, the current or voltage applied to the battery 140 may be terminated. As described below in more detail, the test circuitry can selectively couple to individual cells within the battery 140 if appropriate midpoint connections are provided. A power on self test (POST) and/or watchdog timer can be selectively provided within test circuitry 252 in order to improve the reliability of the device. In one configuration, a “start” button is provided on the user I/O 220 which can be used to initiate the charge/discharge cycle. Over voltage, current and temperature protection is preferably provided in order to protect the battery and the test circuitry.

FIG. 8 shows graphs of battery voltage and battery current during a constant voltage charging mode. As illustrated in FIG. 8, during a first phase of operation, a constant current is applied to the battery. In a second period, a constant voltage is applied to the battery followed by a waiting time. These periods can be cycled in order to maximize battery charge. Similarly, FIG. 9 shows a constant current discharging mode. In such a configuration a constant is applied to the battery for a first period of time. The discharge current is then brought to zero amps.

FIG. 10 is a front perspective view of battery 140 when configured as an electrical vehicle (EV) type battery. In such a configuration, the battery is made up of four cells in which two parallel pairs of cells are connected in series providing a total of four cells. The battery includes a positive connector 400 and a negative connector 402 including a midpoint connector 404. There are two different versions of this type of battery. FIG. 11 illustrates a second configuration in which the positive and negative connections 400, 402 are reversed. In one aspect, the present invention includes a cradle 350 configure to couple to electrical (EV) vehicle batteries configured either in the configuration shown in FIG. 10 or 11.

Similarly, hybrid electric vehicles (HEV) include two types of battery packs. FIG. 12A is a front perspective view and FIG. 12B is a rear perspective view of a first type of hybrid electric battery pack 140. In FIG. 12A, battery 140 includes end terminals 420 and 422. Typically, the hybrid electrical vehicle (HEV) battery consists of eight individual cells connected in series. The inner cell connectors provide inner cell connections between each of the eight batteries for a total of seven inner cell connections in addition to the two end connections. An inner cell connector 424 is provided having a “key” on the left side. In FIG. 12B, a second inner cell connector 426 is shown in which the “key” is opposite the key shown of connector 424 and is positioned on the right side. FIGS. 13A and 13B are front and rear perspective view, respectively, of a second hybrid electric battery 140. In FIG. 13A, end connectors 430 and 432 are illustrated along with an inner cell connector 434 having a “key” on the right side of the illustration. In FIG. 13B, a second inner cell connector 436 is illustrated in which the “key” is positioned on the left side of the figure. In one aspect, the present invention provides a cradle 350 for coupling to either the battery pack configuration shown in FIGS. 12A, 12B or the configuration shown in FIG. 12A, 12B or 13A, 13B.

FIG. 14 is an electrical schematic diagram of switching circuitry 450 used to selectively couple test circuitry 352 to cells within the battery 140 through the inner cell connector 372. In FIG. 14, two inner cell connectors 372A and 372B are illustrated for use in coupling to opposed ends of battery 140 when configured for a hybrid electric vehicle as illustrated in FIGS. 13A and 13B. Switching circuitry 450 includes four relay type switches 452A, 452B, 452C and 452D. Each of the relays 452 include two switches which each have an electrical connection to one of two connections in connector 372A, 372B connecting to an inner cell battery. A switch controller 454 is optically isolated from other circuitry and includes a transistor which drives coils within each of the relay switches 452A, B, C, and D. By selectively actuating the relays 452A, B, C, and D, the polarity of the electrical connections to the inner cell batteries can be reversed. Thus, in one embodiment, circuitry within test circuitry, for example measurement circuitry 272 shown in FIG. 3, senses a voltage of the inner cell connection and selectively actuates relays 452A, B, C and D through controller 454 to obtain the desired polarity on the electrical connection. Similarly circuitry can be used to select a desired polarity of electrical connections to the end points 400, 402 shown in FIGS. 10 and 11 as well as the end point connections 420, 422 and 430, 432 shown in FIGS. 12A and 13A, respectively. Circuitry 450 can be located in test circuitry 352 or can be located within cradle 350 as desired.

In one aspect, the present invention provides one or more cradle configuration for receiving a battery 140 and coupling the battery 140 to circuitry device 200. The cradle configuration allows coupling process to be at least partially automated thereby reducing the time required by an operator as well as the likelihood of operator error in providing the coupling. The cradle and associated circuitry can be configured to select a desired polarity of the connections to the battery and physically secure the battery for testing, charging, discharging, etc. This also allows a single cradle to be used with more than one battery configuration.

FIG. 15 is an exploded perspective view of battery 140 adjacent to cradle 350. In the configuration of FIG. 15, battery 140 is configured as an electric vehicle (EV) battery. In FIG. 15, cradle 350 is illustrated as including a base 500, a cover 502 and latches 504 to secure cover 502 to base 500. Locking tabs 508 are illustrated in open position. A safety switch 510 is also shown and configured to actuate when lid 502 is closed. FIG. 16 is a perspective view showing battery 140 and inserted into base 500. Connectors 206 and 208, and midpoint test connector 372 are shown. These are configured to make contact with battery terminals 202 and 204 and 370. In FIG. 17, the locking tabs 508 are rotated into position thereby secure the battery 140 against Kelvin connections 206, 208 and midpoint connector 372. This also secures the battery 140 within the base 350 whereby cover 502 may be closed and latched and secured with latches 504 as illustrated in FIG. 18. FIG. 19 is a partial cutaway view plan view of base 500. In FIG. 19, operating of locking tabs 508 is shown further. Connectors 206, 208 and midpoint connector 372 are shown as being spring-loaded and urged against connectors 208, 202 and 370, respectively, of battery 140. Note that when the cover 502 is closed, switch 510 is pushed downward and can thereby be used to provide fail safe operation of device without having a cover 502 in the closed position. A temperature sensor 509 such as a thermometer is positioned adjacent battery 140 to measure its temperature during charging and discharging.

FIG. 20 is a perspective view of cradle 350 configured to receive a hybrid electric vehicle (HEV) style battery 140. In the configuration of FIG. 20, cradle 350 contains a base 550, a cover 552 and latches 554. In order to couple to a hybrid electric vehicle battery, the base 550 includes inner cell electrical (or midpoint) connectors 372A, 372B which are configured to couple to inter cell connector 424 and 436 (or 434 and 436), respectively, of battery 140. A safety switch 560 is also illustrated. When battery 140 is inserted into base 550, a slidable portion 555 can be pushed towards battery whereby the battery is secured and electrical contact is made. In rotatable actuator 564 is turned to thereby secure moveable portion 565 in place. Once the battery is secured, the cover 552 can be closed and latched as illustrated in FIG. 23. In this position, the switch 560 is actuated to thereby ensure that the cover 552 has been closed prior operation of the device.

FIG. 24 is a side cross-sectional view of base 550 showing the actuator 564 in greater detail. As illustrated in FIG. 24, the actuator 564 can be rotated. Prior to rotation of actuator 564, moveable portion 565 is slid toward the battery 140 to thereby secure the battery into base 550. A locking disc 590 is slidably received in a track 592. The rotation of actuator 564 causes the locking disc 590 to be urged against track surface 594 to thereby secure the moveable portion 565 in position.

FIG. 25 is a perspective view of Kelvin connections 206 and 208 and midpoint connector 372A in greater detail. As illustrated in FIG. 25, midpoint connector 372A includes four electrical connectors 580 configured to couple to the midpoint connections between four of the batteries or cells within the hybrid electric vehicle battery 140. Alignment tabs 582 are arranged to position the battery 140 within the base 580 and align the electrical connectors 580 with the midpoint connectors to the individual cells. The connectors 580 are arranged to couple to electrical connections inner cell connectors 424 and 434. A similar connector 372B is provided opposite connector 372A and arranged to couple to inner cell connectors 426 and 436.

FIG. 26 is a top perspective view of base 550 having the battery 140 inserted therein prior to rotation of actuator 564. FIG. 27 is a top view showing battery 140 positioned in base 550 prior to movement of moveable portion 565 into position against the battery 140. In FIG. 27, moveable portion 565 has been moved into position and secured in position by rotating rotatable actuator 564.

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. As discussed above, the step of identifying can be performed based upon various parameters. Some of these parameters can be independently adjusted by the testing device or otherwise, for example voltage or state of charge for a particular battery or cell. Other parameters cannot be changed, for example, conductance, impedance, etc. In preparing a replacement battery pack, the parameters which can be adjusted independently may be changed as desired, for example, by charging or discharging a battery in order to provide a better match with other batteries in the replacement pack. The step of identifying can be configured such that a greater weight can be given to those parameters which cannot be adjusted. In such a configuration, prior to assembling the replacement battery pack, parameters which can be adjusted to more closely match one another can be changed accordingly. Further, an information in a database can be developed that relates a voltage or state of charge to conductance or impedance for a specific type of battery. In such a situation, if the database information indicates that a match will be difficult to obtain following equalization of adjustable parameters, the measurement device and/or method can be configured such that that particular battery will not be used and thereby saving time during the refurbishing process. Typically, a battery will comprise a lithium ion battery; another example technology is a nickel metal hydrate battery. However, the present invention is not limited to these battery configurations and may be implemented with other battery technologies. Typically electrical vehicle batteries will include four cells for battery module while hybrid electric vehicle batteries will include eight cells per battery module. The connections to a cell or battery can be single connections or Kelvin connections.

Claims

1. An apparatus for testing a battery of a battery pack from an electric vehicle, comprising: test circuitry configured to perform a battery test on the battery;a cradle configured to receive the battery, the cradle comprising: first and second connectors configured to electrically connect the test circuitry to end connectors of the battery, wherein the first and second connectors comprise Kelvin connectors;at least one midpoint test connector configured to electrically connect the test circuitry to an electrical midpoint between the end connectors, wherein the midpoint test connector is keyed and arranged to fit with a battery midpoint connector on the battery;a base arranged to receive the battery therein;switch circuitry coupled to the at least one midpoint test connector arranged to reverse a polarity of a connection to the battery through the at least one midpoint test connector, the switch circuitry including: at least one relay type switch electrically connected to first and second input connections of the at least one midpoint test connector and first and second output connections of the test circuitry, each relay type switch includes a first switch and a second switch, wherein when the first and second switches are selectively in a first polarity configuration the first switch electrically connects the first input connection to the first output connection and the second switch electrically connects the second input connection to the second output connection and wherein when the first and second switches are selectively in a second polarity configuration that is reversed from the first polarity configuration the first switch electrically connects the second input connection to the first output connection and the second switch electrically connects the first input connection to the second output connection;a switch controller operated by the test circuitry including an optoisolator and a transistor arranged to energize the at least one relay type switch;an actuator arranged to lock the battery in the base and urge the battery into electrical contact with the first, second and midpoint connectors; anda cover arranged to cover the base.

2. The apparatus of claim 1 wherein the actuator comprises a lock mechanism to secure the battery in the cradle.

3. The apparatus of claim 1 wherein the cradle includes a temperature sensor.

4. The apparatus of claim 1 wherein the at least one midpoint test connector includes a plurality of electrical connectors configured to couple to a plurality of electrical midpoints between the end connectors of the battery.

5. The apparatus of claim 1 including a second midpoint test connector configured to couple to additional midpoint connections between the end connectors of the battery.

6. The apparatus of claim 5 wherein the second midpoint connector is carried on a slidable portion.

7. The apparatus of claim 6 including a lock mechanism to secure the slidable portion to the base of the cradle.

8. The apparatus of claim 1 wherein the cradle includes a switch actuated by the cover when the cover is in a closed position.

9. The apparatus of claim 1 wherein the test circuitry is configured to measure a dynamic parameter of the battery.

10. The apparatus of claim 1 wherein the actuator comprises a locking tab.

11. The apparatus of claim 1 wherein the actuator comprises a rotatable actuator.

12. The apparatus of claim 1 wherein the switch circuitry coupled to the at least one midpoint test connector comprises a second relay type switch electrically connected to third and fourth input connections of the at least one midpoint test connector and third and fourth output connections of the test circuitry, the second relay type switch including a first switch and a second switch.

13. The apparatus of claim 12 wherein when the first and second switches of the second relay type switch are selectively in a third polarity configuration the first switch of the second relay type switch electrically connects the third input connection to the third output connection and the second switch of the second relay type switch electrically connects the fourth input connection to the fourth output connection and wherein when the first and second switches of the second relay type switch are selectively in a fourth polarity configuration that is reversed from the first polarity configuration the first switch of the second relay type switch electrically connects the fourth input connection to the third output connection and the second switch of the second relay type switch electrically connects the third input connection to the fourth output connection.