DC pulse battery testing device and method for determining a battery type

Abstract

The invention relates to a method for identifying a battery type (Pb, Li ion) by means of a battery testing device (1), having the steps: application of a DC pulse having a current strength (IB) of at least 30. Ampere to a battery (18) to be tested for at least five seconds; before the application of the pulse, measurement of a pre-pulse voltage (U0) of the battery; during the application of the pulse, measurement of a pulse voltage (U1) of the battery; determination of a transition voltage difference between the pre-pulse voltage and the pulse voltage; determination of a characteristic of a transition voltage difference parameter in dependence upon the transition voltage difference; assignment of a specific battery type (Pb, Li ion) to the tested battery in dependence upon the characteristic; and a battery testing device and a battery testing system.

Claims

1. A method for identifying a battery type (Pb, Li ion) by means of a battery testing device (1), having the steps: application of a DC pulse having a current strength (IB) of at least 30 Ampere to a battery (18) to be tested for at least five seconds, before the application of the pulse, measurement of a pre-pulse voltage (U0) of the battery, during the application of the pulse, measurement of a pulse voltage (U1) of the battery, determination of a transition voltage difference between the pre-pulse voltage and the pulse voltage, determination of a characteristic of a transition voltage difference parameter in dependence upon the transition voltage difference, assignment of a specific battery type (Pb, Li ion) to the tested battery in dependence upon the characteristic.

2. The method according to claim 1, wherein the DC pulse has an at least substantially constant current strength (IB) in the range of between 60 and 120 Ampere.

3. The method according to claim 1, wherein the DC pulse is applied to the battery for a period in the range of between eight and 15 seconds.

4. The method according to claim 1, having: measurement of at least one further pulse voltage (U2-U14) of the battery at at least one further timepoint (T2-T14) during the application of the pulse, determination of a characteristic of at least one pulse voltage difference parameter in dependence upon a pulse voltage difference between two measured pulse voltages, assignment of a specific battery type to the tested battery in dependence upon the characteristic.

5. The method according to claim 4, wherein a pulse voltage (U1-U14) of the battery is measured at a plurality of timepoints (T1-T14), especially a total of ten or fifteen timepoints, during the application of the pulse, and wherein a characteristic of at least one further pulse voltage difference parameter is determined in dependence upon at least one pulse voltage difference between two of the measured pulse voltages, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

6. The method according to claim 4, wherein a characteristic of a voltage difference mean value parameter is determined in dependence upon a mean value of voltage differences arising between voltages measured at adjacent times before or during the application of the pulse, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

7. The method according to claim 4, wherein a characteristic of a voltage difference discharge parameter is determined in dependence upon the development over time of the voltage changes between voltages measured at adjacent times before or during the application of the pulse, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

8. The method according to claim 1, wherein a characteristic of a pre-pulse voltage parameter is determined in dependence upon the pre-pulse voltage (U0), and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

9. The method according to claim 1, wherein a pulse response current (I1-I14) is measured at each of a plurality of timepoints (T1-T14) during the application of the DC pulse, and wherein a characteristic of at least one pulse current difference parameter is determined in dependence upon at least one current difference between two measured pulse response currents, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

10. The method according to claim 1, wherein a characteristic of an application current difference parameter is determined in dependence upon at least one application current difference between the application current (IB) and a measured pulse response current, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

11. The method according to claim 1, wherein a pulse response current (I1-I14) of the battery is measured at a plurality of timepoints (T1-T14), especially a total of ten or fifteen timepoints, during the application of the pulse, and wherein a characteristic of at least one further pulse current difference parameter is determined in dependence upon at least one current difference between two of the measured pulse response currents, and wherein a specific battery type is assigned to the tested battery in dependence upon the characteristic.

12. The method according to claim 11, wherein both a pulse voltage (U1-U14) and a pulse response current (I1-I14) of the battery are measured at a plurality of timepoints (T1-T14), especially a total of ten or fifteen timepoints, during the application of the pulse.

13. The method according to claim 1, wherein in dependence upon the assignment of the tested battery to a specific battery type in respect of one or more parameters, especially the assignment parameters under consideration, a specific battery type is allocated as test result if a characteristic which has been assigned to the same battery type (Pb, Li ion) is present in respect of all of the parameters under consideration or in respect of a predetermined proportion thereof.

14. The battery testing system operated by means of a method according to claim 1.

Description

(1) Advantageous arrangements of the different aspects of the invention are the subject matter of the subsidiary claims. Further features, advantages and possible applications of the invention will be found in the following description in conjunction with the Figures, which show, partly in diagrammatic form:

(2) FIG. 1 in a sectional view a battery testing device in accordance with an embodiment of the invention with a connected battery to be measured;

(3) FIG. 2 a U-t diagram of a test result for a Li ion battery when a method in accordance with an embodiment of the invention is carried out;

(4) FIG. 3 a U-t diagram of a test result for a lead battery when a method in accordance with an embodiment of the invention is carried out; and

(5) FIG. 4 a flow diagram of a battery test which is carried out with a battery testing device in accordance with an exemplary embodiment of the invention using a method in accordance with an exemplary embodiment of the invention.

(6) FIGS. 1, 2 and 3 illustrate a battery testing device in accordance with an embodiment of the invention which can be operated by means of a method for identifying a battery type in accordance with an embodiment of the invention. The described battery testing device 1 is especially arranged to identify batteries 2 of the “lead battery” battery type and of the “lithium ion battery” battery type that are installed in motor vehicles and to differentiate them from one another. Irrespective thereof it will be understood that the invention can also be applied to any other battery types.

(7) FIG. 1 shows a battery testing device 1 which, for carrying out the method for identifying the battery type, is connected to a battery 2 to be tested. In the diagram the battery 2 is separate; in accordance with the invention, however, the battery can also be installed in, for example, a motor vehicle (not shown herein).

(8) The battery testing device 1 has: a voltage measuring unit 4, a DC generator 6 and optionally a current measuring unit 7. By means of the DC generator 6, a DC pulse can be generated over a period of one or more seconds or longer. The voltage measuring unit 4, if applicable the current measuring unit 7 and the DC generator 6 are connected, electrically and for signal transmission, to a control unit 10 of the battery testing device 1 via the line 8.1 indicated by a dotted line. The control unit 10 is additionally connected to a memory unit 12, a display unit 14 and a sensor arrangement 16 by means of further lines. In addition, the control unit 10 is connected by means of a further line 8.5 to a timer 13 which enables the DC pulse to be applied to the battery 2 being tested over a predetermined period of time, in this case preferably five or ten seconds. The timer is preferably in the form of a conventional component of the control unit 10.

(9) The battery 2 to be tested has an energy storage means 18 having secondary cells (not shown) of a specific battery type and poles 20 (positive, represented by the + sign) and 22 (negative, represented by the—sign) connected to the energy storage means 18. In addition, the battery 2 has a battery management system 24 which has sensors (not shown) for detecting a temperature, a state of charge and/or an ageing state of the battery.

(10) For carrying out the exemplary method for identifying the battery type of the battery 2 being tested, each of the poles 20 and 22 is connected by means of a connector to the battery testing device 1. The connector has for each pole 20 and 22 a power connection 28, 30 for application of the DC current and a measurement connection 32, 34 for voltage measurement and accordingly for measurement of a plurality of voltage values U at different timepoints t.sub.1, t.sub.2, t.sub.3 and t.sub.4.

(11) In addition, in this exemplary embodiment there can optionally be arranged on the battery 2 a temperature sensor 36, which is connected to the sensor arrangement 16, for measuring the temperature of the surface and/or environment of the battery. In this exemplary embodiment that sensor 36 is then arranged close to an interface 38 via which the sensor arrangement 16 is connected to the battery management system 24, but could also be arranged at some other location specific to the application.

(12) The mode of operation of the battery testing device 1 in accordance with the described embodiment of a test method according to an embodiment of the invention in which lithium ion batteries and lead batteries are to be differentiated is described below with reference to FIGS. 2 and 3.

(13) In the embodiment shown in FIGS. 2 and 3, the first assignment parameter 41, the second assignment parameter 42 and the third assignment parameter 43 are taken into account in order to determine to which of the two mentioned battery types the battery being tested belongs.

(14) The third assignment parameter 43 relates to the timepoint T.sub.1 before the introduction of the DC pulse 100 and is dependent upon the measured first voltage 51. Values for the first voltage 51 of 13 V (third threshold value 73) or more are assigned to lithium ion batteries, lower values to lead batteries.

(15) The second assignment parameter 42 relates to the transition from the timepoint T.sub.1 before the introduction of the DC pulse 100 to the timepoint T.sub.2 at the beginning of the DC pulse 100 and is dependent upon the first voltage difference 61 between the measured first voltage 51 and the measured second voltage 52. Values for the first voltage difference 61 of 0.6 V (first threshold value 71) or more are assigned to lead batteries, lower voltage differences to lithium ion batteries.

(16) The first assignment parameter 41 relates to the build-up of the voltage during the DC pulse 100 and is dependent upon the second voltage difference 62 between the measured second voltage 52 and the measured third voltage 53. Values for the second voltage difference 62 of 0.1 V (second threshold value 72) or more are assigned to lead batteries, lower voltage differences to lithium ion batteries.

(17) A test result (that is to say the information “Li ion battery” or the information “lead battery”) is output on the display 14 only if the characteristic of each of the three assignment parameters 41, 42 and 43 is assigned to the corresponding battery type. In that respect the three assignment parameters are equally weighted.

(18) The third assignment parameter results from the measured first voltage 51 and has the characteristics greater than or equal to 13 V and less than 13 V. The characteristic greater than or equal to 13 V is assigned to batteries of the “Li ion” type, because the latter have corresponding voltages. The characteristic less than 13 V is accordingly assigned to batteries of the “lead” type.

(19) FIG. 2 shows the case where, as a result of the characteristics of the three assignment parameters 41, 42 and 43, the battery type “Li ion” is assigned to the battery being tested. The first voltage 51.sub.L at timepoint T.sub.1 is 13.2 V and therefore more than 13 V. That characteristic of the third assignment parameter 43 is consequently assigned to a lithium ion battery.

(20) The second voltage 52.sub.L at timepoint T.sub.2 is 13.6 V. The first voltage difference 61.sub.L is therefore 0.4 V and consequently less than 0.6 V. Accordingly, that characteristic of the first assignment parameter 41 is assigned to a lithium ion battery.

(21) The third voltage 53.sub.L at timepoint T.sub.3 is 13.65 V. The second voltage difference 62.sub.L is therefore 0.05 V and consequently less than 0.1 V. Accordingly, that characteristic of the second assignment parameter 42 is likewise assigned to a lithium ion battery.

(22) Since the characteristics of each of the assignment parameters 41, 42 and 43 are assigned to a lithium ion battery, “Li ion battery” is output as the test result on the display 14.

(23) FIG. 3 illustrates the case where, as a result of the characteristics of the three assignment parameters 41, 42 and 43, battery type “lead” is assigned to the battery being tested. The first voltage 51.sub.B at timepoint t.sub.1 is 12.6 V and therefore less than 13 V. That characteristic of the third assignment parameter 43 is consequently assigned to a lead battery.

(24) The second voltage 52.sub.B at timepoint t.sub.2 is 13.4 V. The first voltage difference 61.sub.B is therefore 0.8 V and consequently more than 0.6 V. Accordingly, that characteristic of the first assignment parameter 41 is assigned to a lead battery.

(25) The third voltage 53.sub.B at timepoint t.sub.3 is 13.6 V. The second voltage difference 62.sub.B is therefore 0.2 V and consequently more than 0.1 V. Accordingly, that characteristic of the second assignment parameter 42 is likewise assigned to a lead battery.

(26) Since the characteristics of each of the assignment parameters 41, 42 and 43 are assigned to a lead battery, “lead battery” is output as the test result on the display 14.

(27) Relevant environmental and operating conditions of the battery being tested, such as temperature, state of charge or ageing state, can be recorded by means of the sensor arrangement 16 and/or a battery management system 24 of the battery 2 and in the embodiment shown can optionally be incorporated into the reliability criterion and/or into the assessment of the assignment parameters and/or as further assignment parameters.

(28) If, in an embodiment not shown, such environmental and/or operating conditions are not determined by means of a battery management system of the battery being tested, it is possible for values relating to the current temperature of the battery to be recorded directly at one of the two battery poles to which the connectors 28, 30, 32 and 34 are in any case applied, for example by means of a different temperature sensor (not shown), especially the sensor arrangement 16. One of those connectors can be configured to receive the temperature sensor and its connection, for example at a binding post. For the purposes of the invention the temperature of the metal battery pole can be sufficiently representative of temperatures in the interior of the battery. In such an embodiment a state of charge can be determined in dependence upon a voltage “U” applied to and measured at the measurement connectors 32, 34, an ageing state in dependence upon a DC resistance of the battery which is then to be measured.

(29) In the exemplary embodiment of FIGS. 2 and 3, current values, for example measured at timepoints t.sub.2 and t.sub.3, are not determined and are not used in the determination of the battery type, but this would be readily possible within the scope of the invention using a battery testing device according to FIG. 1. The battery testing device according to FIG. 1, however, is arranged to measure such current values and to use determined measured values or measured value differences in accordance with the invention.

(30) In the exemplary embodiment of FIGS. 2 and 3, measurement of current values and/or voltage values at a timepoint t.sub.4 after the DC pulse is not carried out and is not used in the determination of the battery type. The battery testing device according to FIG. 1, however, is arranged to carry out such measurements and to use determined measured values or measured value differences in accordance with the invention.

(31) In the embodiment shown, no battery type is assigned if the results from the characteristics of the first and second assignment parameters, preferably also of the third assignment parameter, do not point to the same battery type. A conflicting result can initiate repetition of the measurement.

(32) In FIG. 4, in respect of the method carried out for identifying a battery type there is described an exemplary embodiment which is independent of that of FIGS. 1 to 3; the battery testing device used for that purpose can correspond to that of FIG. 1 but can also be constructed in accordance with a different exemplary embodiment of the invention. FIG. 4 shows a flow diagram of a battery test which is carried out with a battery testing device 1 in accordance with an exemplary embodiment of the invention using a method in accordance with an exemplary embodiment of the invention.

(33) The battery test in accordance with this exemplary embodiment serves for differentiating between batteries connected to a motor vehicle. Many current vehicle models, depending upon the standard or extra equipment provided, are provided with either a battery of the lithium ion type (Li ion) or with a battery of the lead battery type (Pb). In the case of Just-in-Time or Just-in-Sequence production which is provided in motor vehicle assembly lines, it is routinely the case that, in an assembly line, vehicles fitted with a lead battery and fitted with a lithium ion battery are assembled in succession in an irregular order.

(34) For various functions—such as, for example, the charging of the vehicle battery in accordance with the vehicle customer's or the vehicle manufacturer's requirements—a charging device provided on the assembly line must have inter alia a battery testing device 1 for identifying the battery type of the battery 18 installed. Such a battery testing device 1 and the performance of a battery test for identifying the battery type is described in this exemplary embodiment. The individual steps of the method with the functional relationships are explained and described in detail below:

(35) In step 110, the vehicle battery 18, connected to the on-board network of the vehicle, is connected to the battery testing device 1 by connecting the connectors 28, 30, 32 and 34 to the poles 20 and 22.

(36) In step 120—that is to say before application of the DC pulse to the battery—the pre-pulse voltage U0 and the pre-pulse current I0 of the battery are measured at a timepoint T0.

(37) In step 130, a DC pulse having a voltage of 14.4 V and a current strength of 80 A is applied to the battery for a period ΔT of ten seconds, the DC pulse being applied to the battery from the start timepoint Ts to the end timepoint Te. The measurement timepoint T0 is before the start timepoint Ts; the measurement points T1 to T14 are between the start timepoint Ts and the end timepoint Te (see Table in FIG. 4). In other exemplary embodiments, a different voltage and/or a different current strength can be applied.

(38) During the application of the DC pulse, a pulse voltage U1 to U4 and a pulse response current I1 to I4 are each measured at time intervals, preferably uniformly distributed time intervals, at various timepoints T1 to T14.

(39) On the basis of the measured voltages U0 to U14 and response currents I0 to I14, the respective characteristics of various assignment parameters are determined in method steps 140 to 180.

(40) On the basis of the characteristic determined in each case there is preferably determined for each assignment parameter used, by comparison with a stored table for that assignment parameter, whether and, if so, to which battery type the tested battery is to be assigned in respect of that assignment parameter. The appropriate table preferably contains a plurality of characteristics to be expected in respect of the assignment parameter for each of those characteristics for assignment to a battery type.

(41) The assignment parameters used for differentiating between lead batteries and lithium ion batteries in the described exemplary embodiment are described below in connection with that method step in which they are applied:

(42) Steps 140 to 160 serve especially but not exclusively for the simplest possible way of differentiating between fully charged batteries of different battery types.

(43) In step 140, a characteristic of an application current difference parameter is determined from the application current difference between the application current IB and the last measured pulse response current I14. If that current difference is greater than a threshold value (especially greater than five to 20 Ampere, for example greater than 10 Ampere), battery type Pb is assigned to the tested battery in respect of that assignment parameter.

(44) In addition, in step 140, a characteristic of a pulse current difference parameter is determined from a current difference between the first pulse response current I1 and a later pulse response current (for example I4 or I9). If that current difference reveals that the pulse response current measured later is greater, especially significantly greater, than the pulse response current measured earlier, battery type Pb is assigned to the tested battery in respect of that assignment parameter.

(45) If the two assignments determined in step 140 point to a lead battery, battery type Pb is allocated to the battery being tested (see “j” by the arrow from method step 140 in FIG. 4 to the allocation “Pb”).

(46) If, in step 140, it is not possible to make a clear assignment to a lead battery (see “n”), in step 150 reference is additionally made to a pre-pulse voltage parameter. If the pre-pulse voltage U0 is less than a threshold value (especially less than 12.5 to 12.9 Volt, for example less than 12.8 Volt), battery type Pb is assigned to the tested battery in respect of that assignment parameter. Virtually all lead batteries fulfil that criterion, with the possible exception of batteries which have been charged immediately beforehand.

(47) If, in addition to the assignment determined in step 150, the assignment determined in step 140 in respect of the application current difference parameter points to a lead battery, battery type Pb is allocated to the battery being tested (see “j” by the arrow from method step 150 in FIG. 4 to the allocation “Pb”).

(48) If, in step 150, it is likewise not possible to make a clear assignment to a lead battery (see “n”), in step 160 reference is additionally made to a further pre-pulse voltage parameter. If the pre-pulse voltage U0 is greater than a threshold value (here especially greater than 12.9 to 13.6 Volt, for example greater than 13.2 Volt), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(49) In addition, in step 160, a characteristic of a further pulse current difference parameter is determined from a current difference between the first pulse response current I1 and the last pulse response current I14. If this current difference reveals that, as the pulse progresses, the current strength falls by more than a threshold value (especially greater than five to 20 Ampere, for example greater than 10 Ampere), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(50) If the two assignments determined in step 160 point to a lithium ion battery, battery type Li ion is assigned to the battery being tested (see “j” by the arrow from method step 160 in FIG. 4 to the allocation “Li ion”).

(51) Depending upon the application and the required information accuracy, in the exemplary embodiment described here it can also be sufficient, especially for differentiating between fully charged batteries, to carry out only one or two of steps 140, 150 and 160 in order to allocate a battery type to the battery being tested.

(52) Steps 170 to 180 serve especially but not exclusively for the simplest possible way of differentiating between non-fully charged batteries of different battery types. Those steps therefore also make it possible to identify the battery type in the case of batteries in any state of charge.

(53) In step 170, joint consideration is given to a plurality of different assignment parameters for which the respective characteristic of the tested battery is determined in sub-steps 171 to 175.

(54) For each of sub-steps 171 to 175—that is to say for the respectively associated assignment parameter—there is determined, by comparison with the respective table, whether its characteristic is to be assigned to a lithium ion battery. If that is the case (see “j” in detailed view of step 170), a counter x is increased by one step (x=x+1).

(55) In step 180, battery type Li ion is assigned to the battery being tested if the counter x reaches a certain threshold value (see allocation “j” at step 180), in the present case, for example, a threshold value of three. In the exemplary embodiment that means that battery type Li ion is allocated when at least three of assignment parameters 171 to 175 indicate assignment to the battery type Li ion. If that is not the case, battery type Pb is allocated (see allocation “n”).

(56) The assignment parameters of sub-steps 171 to 175 are described in greater detail below:

(57) In sub-step 171, reference is made to a further pre-pulse voltage parameter. If the pre-pulse voltage U0 reaches a threshold value or is greater than that value (here especially greater than or equal to 12.5 to 13.2 Volt, for example greater than or equal to 12.8 Volt), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(58) In sub-step 172, reference is made to a transition voltage difference parameter the characteristic of which is determined from a voltage difference between the pre-pulse voltage U0 and the first pulse voltage U1. If that voltage difference reveals that after the application of the DC pulse to the battery the voltage increases by less than a threshold value (here especially 1.5 to 2.2 Volt, for example 1.8 Volt), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(59) In sub-step 173, a characteristic of a pulse voltage difference parameter is determined from a voltage difference between the first pulse voltage U1 and the last pulse voltage U14. If that voltage difference reveals that, as the pulse progresses, the voltage increases by less than a threshold value (especially less than 0.20 to 0.40 Volt, for example less than 0.30 Volt), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(60) In sub-step 174, a characteristic of a voltage difference mean value parameter is determined by determining a mean value of voltage differences arising between all pairs of voltages measured at adjacent times (mean value of [U1-U0, U2-U1, . . . , U14-U13]). If that mean value is smaller than a threshold value (especially less than 0.1 to 0.2 Volt, for example less than 0.16 Volt), battery type Li ion is assigned to the tested battery in respect of that assignment parameter. As further assignment parameters not considered here it is also possible to take into account a mean absolute deviation of the voltage difference from the mean value calculated in sub-steps 174.

(61) In sub-step 175, a characteristic of a voltage difference discharge parameter is determined by determining the development over time of the voltage changes between voltages measured at adjacent times. For that purpose, for example, a method of numerical integration with increasing difference quotients can be used. If the value so determined for the discharge remains below a specific threshold value (especially less than 0.05 to 0.1, for example less than 0.075), battery type Li ion is assigned to the tested battery in respect of that assignment parameter.

(62) Depending upon the application and the required information accuracy, in the exemplary embodiment described here it can also be sufficient, especially for differentiating between partially charged batteries, to carry out only one or two or three or four of sub-steps 171, 172, 173, 174 and 175 in order to allocate a battery type to the battery being tested.

(63) If, in that context, the number of assignment parameters used in step 170 is different from that shown in FIG. 4, it is accordingly also possible for the threshold value to be adapted in respect of the counter x for the allocation of a specific battery type. Independently of the number of assignment parameters considered in step 170, by means of a counter increase y (x=x+y) matched to a specific assignment parameter, it is possible to weight the individual assignment parameters if the characteristic of one or more specific assignment parameters is more relevant to the allocation of the battery type than the characteristic of one or more other assignment parameters.

(64) For example, once it has been ensured that the battery being tested has been connected to the vehicle but no large consumers, such as, for example, an air-conditioning system or a seat heating system, are so configured, reliable identification of the battery type can also be carried out preferably only on the basis of steps 110, 120, 130, 150, 172, 173 and 174.