Apparatus and method for diagnosing battery

Abstract

An apparatus for diagnosing a battery, according to one embodiment of the present invention, comprises: a profile acquisition unit for acquiring a charging profile that indicates a voltage change in the battery during charging; and a control unit for calculating a voltage change amount of the battery at a charging start time point of the charging profile, calculating a target resistance of the battery on the basis of the calculated voltage change amount and the initial SOC of the battery at the charging start time point, and comparing the target resistance with a first resistance profile, in which the target resistance of the battery calculated in a previous charging cycle is stored, thereby diagnosing the state of the battery.

Description

Battery diagnostic device and method

[0001] This application claims priority to Korean Patent Application No. 10-2024-0061802, filed on May 10, 2024, the entire contents of which are disclosed in the specification and drawings of the said application are incorporated herein by reference.

[0002] The present invention relates to a battery diagnosis device and method, and more particularly, to a battery diagnosis device and method for diagnosing the state of a battery based on resistance generated during a charging process.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage batteries, robots, and satellites has been in full swing, research into high-performance batteries capable of repeated charging and discharging is actively being conducted.

[0004] Currently commercialized batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are receiving attention for their advantages of being able to charge and discharge freely, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based batteries.

[0005] While extensive research is being conducted on these batteries to improve capacity and density, improving lifespan and safety is also crucial. To improve battery safety, technology is required to accurately diagnose the current battery condition.

[0006] In particular, it is necessary to prevent lithium plating on the cathode surface. Lithium plating on the cathode surface can cause side reactions with the electrolyte and alter the battery's kinetic balance, leading to battery degradation.

[0007] Furthermore, lithium plating can cause battery swelling. When swelling occurs, the center of the battery swells more than the edges, creating an uneven pressure distribution within the battery. This can lead to reduced battery performance and sudden electrical failure, a phenomenon known as sudden death.

[0008] The present invention has been devised to solve the above-mentioned problems, and its purpose is to provide a battery diagnosis device and method for diagnosing a battery at risk of sudden death based on the resistance of the battery generated during the charging process.

[0009] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0010] A battery diagnosis device according to one aspect of the present invention may include a profile acquisition unit configured to acquire a charging profile indicating a voltage change of a battery during a charging process; and a control unit configured to calculate a voltage change amount of the battery at a charging start time point of the charging profile, calculate a target resistance of the battery based on the calculated voltage change amount and an initial SOC of the battery at the charging start time point, and diagnose a state of the battery by comparing the target resistance with a first resistance profile in which a target resistance of the battery calculated in a previous charging cycle is stored.

[0011] The above control unit may be configured to calculate the initial resistance based on the voltage change amount and the charging current of the charging process.

[0012] The control unit may be configured to determine the initial resistance as the target resistance when the initial SOC is equal to a preset target SOC.

[0013] The control unit may be configured to calculate the target resistance from the initial resistance based on a resistance table preset to indicate a resistance ratio for each SOC, when the initial SOC is different from the target SOC.

[0014] The above resistance table can be preset to correspond to multiple reference cycles.

[0015] The control unit may be configured to calculate the target resistance based on a resistance table corresponding to the cycle of the battery when the cycle of the battery is the same as any one of the plurality of reference cycles.

[0016] The control unit may be configured to select a plurality of target cycles adjacent to the cycle of the battery from among the plurality of reference cycles when the cycle of the battery is different from the plurality of reference cycles, generate a target resistance table from a resistance table corresponding to the plurality of target cycles, and calculate the target resistance based on the target resistance table.

[0017] The control unit may be configured to calculate the total resistance for the battery by dividing the initial resistance by a resistance ratio corresponding to the initial SOC in the resistance table, and to calculate the target resistance for the battery by multiplying the total resistance by a resistance ratio corresponding to the target SOC in the resistance table.

[0018] The control unit may be configured to determine a first resistance section based on the first resistance profile and compare the first resistance section with the target resistance to diagnose the state of the battery.

[0019] The control unit may be configured to determine a first resistance line for a plurality of resistors included in the first resistance profile, and to determine the first resistance section by adding a preset resistance threshold value to the determined first resistance line.

[0020] The control unit may be configured to diagnose the state of the battery as normal when the target resistance falls within the first resistance range.

[0021] The control unit may be configured to diagnose the state of the battery as abnormal if the target resistance does not fall within the first resistance range.

[0022] The control unit may be configured to calculate a sub-voltage change amount between the voltage of the battery immediately after the charging starts in the charging profile and the voltage at a point in time when the charging has been in progress for a preset period of time, calculate a sub-resistance of the battery based on the calculated sub-voltage change amount, and diagnose a state of the battery based on the target resistance and the sub-resistance.

[0023] The control unit may be configured to determine a second resistance section based on a second resistance profile in which the sub-resistance of the battery calculated in the previous charging cycle is stored, and to diagnose the state of the battery based on a result of comparing the first resistance section with the target resistance and a result of comparing the second resistance section with the sub-resistance.

[0024] The control unit may be configured to determine a second resistance line for a plurality of resistors included in the second resistance profile, and to determine the second resistance section by adding a preset resistance threshold value to the determined second resistance line.

[0025] The control unit may be configured to diagnose the state of the battery as normal when the target resistance belongs to the first resistance section or when the sub-resistance belongs to the second resistance section.

[0026] The control unit may be configured to diagnose the state of the battery as abnormal when the target resistance does not belong to the first resistance section and the sub resistance does not belong to the second resistance section.

[0027] The control unit may be configured to calculate the voltage change amount by calculating the difference between the initial voltage of the battery immediately before the charging starts and the voltage of the battery immediately after the charging starts.

[0028] A battery pack according to another aspect of the present invention may include a battery diagnostic device according to one aspect of the present invention.

[0029] A battery diagnosis method according to another aspect of the present invention may include a profile acquisition step of acquiring a charging profile indicating a voltage change of a battery during a charging process; a voltage change calculation step of calculating a voltage change of the battery at a charging start time of the charging profile; a target resistance calculation step of calculating a target resistance of the battery based on the calculated voltage change and an initial SOC of the battery at the charging start time; and a diagnosis step of diagnosing a state of the battery by comparing the target resistance with a first resistance profile in which a target resistance of the battery calculated in a previous charging cycle is stored.

[0030] According to one aspect of the present invention, a battery diagnostic device can non-destructively diagnose the state of a battery based on the resistance behavior of the battery.

[0031] In particular, the battery diagnostic device can predict and diagnose in advance whether a battery is likely to experience sudden death based on the resistance of the battery.

[0032] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0033] The following drawings attached to this specification serve to further understand the technical idea of ​​the present invention together with the detailed description of the invention described below, and therefore the present invention should not be interpreted as being limited to the matters described in such drawings.

[0034] FIG. 1 is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0035] FIG. 2 is a diagram schematically illustrating a charging profile according to one embodiment of the present invention.

[0036] Figure 3 is an enlarged view of the charging protocol of Figure 2.

[0037] FIG. 4 is a diagram schematically illustrating a first resistance profile according to one embodiment of the present invention.

[0038] Figure 5 is an enlarged view of the first resistance profile of Figure 4.

[0039] FIG. 6 is a diagram schematically illustrating the capacity retention rate of a battery according to one embodiment of the present invention.

[0040] FIG. 7 is a schematic diagram illustrating a resistance table according to one embodiment of the present invention.

[0041] FIG. 8 is a diagram schematically illustrating a second resistance profile according to one embodiment of the present invention.

[0042] Figure 9 is an enlarged view of the second resistance profile of Figure 8.

[0043] FIG. 10 is a schematic drawing of a battery pack according to another embodiment of the present invention.

[0044] FIG. 11 is a schematic drawing of a vehicle according to another embodiment of the present invention.

[0045] FIG. 12 is a diagram schematically illustrating a battery diagnosis method according to another embodiment of the present invention.

[0046] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0047] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0048] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0049] Terms that include ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

[0050] Throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0051] Additionally, throughout the specification, when we say that a part is "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with other elements in between.

[0052]

[0053] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0054] FIG. 1 is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0055] Referring to FIG. 1, the battery diagnostic device may include a profile acquisition unit and a control unit.

[0056] Here, a battery refers to a physically separate, independent cell having a negative terminal and a positive terminal. For example, a lithium-ion battery or a lithium polymer battery may be considered a battery. Furthermore, the battery may be of a cylindrical type, a prismatic type, or a pouch type. Furthermore, a battery may also refer to a battery bank, a battery module, or a battery pack in which multiple cells are connected in series and / or parallel. For convenience of explanation, the term "battery" will be described herein below as referring to a single, independent cell.

[0057] The profile acquisition unit (110) can be configured to acquire a charging profile (CP) indicating a voltage change of the battery during the charging process.

[0058] Specifically, a charge profile (CP) may be a profile that represents the change in voltage according to the time or capacity of the battery from the start of charging to the end of charging during the charging process. For example, a charge profile (CP) may be a profile that represents the correspondence between charging time and voltage. As another example, a charge profile (CP) may be a profile that represents the correspondence between state of charge (SOC) and voltage. As yet another example, a charge profile (CP) may be a profile that represents the correspondence between capacity and voltage.

[0059] Here, since the charging time, capacity based on the charging time, and SOC based on the charging time are interchangeable factors over time, there are no special restrictions on the charging profile (CP). However, for convenience of explanation, the charging profile (CP) is described below as a profile representing the correspondence between SOC and voltage.

[0060] For example, the profile acquisition unit (110) can directly receive the charging profile (CP) of the battery from the outside. That is, the profile acquisition unit (110) can acquire the charging profile (CP) by being connected to the outside via wire and / or wirelessly and receiving the charging profile (CP).

[0061] As another example, the profile acquisition unit (110) can receive battery information regarding the battery's voltage and SOC. Furthermore, the profile acquisition unit (110) can generate a charging profile (CP) based on the received battery information. That is, the profile acquisition unit (110) can acquire a charging profile (CP) by directly generating the charging profile (CP) based on the battery information.

[0062] FIG. 2 is a diagram schematically illustrating a charging profile (CP) according to one embodiment of the present invention. In the embodiment of FIG. 2, the charging profile (CP) can be expressed as an XY graph in which the X-axis is set to SOC and the Y-axis is set to voltage.

[0063] Specifically, the embodiment of FIG. 2 is a charge profile (CP) of a battery that is rapidly charged. For example, charging of the battery starts at SOC S1(%), and rapid charging of the battery ends at SOC S6(%). Then, the battery is rapidly charged while the charge C-RATE decreases at SOCs S2(%), S3(%), S4(%), and S5(%). That is, the charge C-RATE of the SOC section of S1(%) to S2(%) is greater than the charge C-RATE of the SOC section of S2(%) to S3(%). The C-RATE of the SOC section of S2(%) to S3(%) is greater than the C-RATE of the SOC section of S3(%) to S4(%). The C-RATE of the SOC section of S3(%) to S4(%) is greater than the C-RATE of the SOC section of S4(%) to S5(%). The C-RATE of the SOC section of S4(%) to S5(%) is greater than the C-RATE of the SOC section of S5(%) to S6(%).

[0064] The profile acquisition unit (110) may be connected to the control unit (120) so as to be able to communicate with it. For example, the profile acquisition unit (110) may be connected to the control unit (120) via wire and / or wirelessly. The profile acquisition unit may transmit the acquired charging profile (CP) to the control unit (120).

[0065] The control unit (120) may be configured to calculate the voltage change amount of the battery at the start of charging of the charging profile (CP).

[0066] Specifically, the battery may be in a no-load state just before charging begins. Therefore, the initial voltage of the battery just before charging begins is the open circuit voltage (OCV).

[0067] Figure 3 is an enlarged diagram illustrating the charging protocol of Figure 2. For example, the SOC of the battery immediately before charging begins is S1 (%), and the voltage is V1 (V).

[0068] And, when charging starts, the battery voltage increases rapidly compared to the initial voltage due to the battery's internal resistance. For example, let's say the terminal voltage of the battery is V, the initial voltage is OCV, the charging current is I, and the battery's internal resistance is R. Here, the terminal voltage of the battery can be expressed according to the formula "V=OCV+IR". That is, immediately after charging starts, the battery voltage can increase by "IR".

[0069] The control unit (120) may be configured to calculate the voltage change amount by calculating the difference between the initial voltage of the battery just before charging begins and the voltage of the battery immediately after charging begins.

[0070] Specifically, the control unit (120) can calculate the voltage change amount by calculating the difference between the OCV of the battery immediately before charging begins and the terminal voltage of the battery immediately after charging begins.

[0071] For example, in the embodiment of FIG. 3, the control unit (120) can calculate the voltage change amount by calculating the formula “V2-V1”.

[0072] The control unit (120) may be configured to calculate the target resistance of the battery based on the calculated voltage change amount and the initial SOC (State of Charge) of the battery at the start of charging.

[0073] Here, the initial SOC is the SOC corresponding to the OCV of the battery. In other words, the initial SOC refers to the SOC of the battery at the point when charging of the battery begins.

[0074] The control unit (120) can be configured to calculate the initial resistance based on the voltage change amount and the charging current of the charging process.

[0075] Specifically, the control unit (120) can calculate the initial resistance based on the voltage change amount and the charging current using Ohm's law. For example, assuming that the voltage change amount is △V and the charging current is I, the control unit (120) can calculate the initial resistance by calculating the formula "△V÷I".

[0076] For example, in the embodiments of FIGS. 2 and 3, it is assumed that the charging current for the SOC section of S1(%) to S2(%) is I. The control unit (120) can calculate the value obtained by dividing the voltage change amount (V2-V1) by the charging current (I) as the initial resistance.

[0077] Additionally, the control unit (120) can calculate the target resistance in a different manner when the initial SOC is different from the target SOC.

[0078] Specifically, the control unit (120) may be configured to determine the initial resistance as the target resistance when the initial SOC is equal to the preset target SOC. Conversely, the control unit (120) may be configured to calculate the target resistance from the initial resistance based on a resistance table preset to indicate the resistance ratio for each SOC when the initial SOC is different from the target SOC. A specific embodiment of how the control unit (120) calculates the target resistance will be described below.

[0079] The control unit (120) may be configured to diagnose the condition of the battery by comparing the target resistance with a first resistance profile (P1) in which the target resistance of the battery calculated in the previous charging cycle is stored.

[0080] Specifically, the first resistance profile (P1) is a profile in which the target resistance of the battery calculated for each past charging cycle is stored. For example, assuming that the current cycle is the nth cycle, the target resistance calculated for the 1st to (n-1)th cycles may be stored in the first resistance profile (P1). Then, when the battery condition diagnosis for the nth cycle is completed, the target resistance calculated for the nth cycle may be stored in the first resistance profile (P1).

[0081] Fig. 4 is a diagram schematically illustrating a first resistance profile (P1) according to one embodiment of the present invention. In the embodiment of Fig. 4, the first resistance profile (P1) can be expressed as an XY graph in which the X-axis is set as a cycle and the Y-axis is set as resistance.

[0082] The control unit (120) may be configured to determine the first resistance section (R1) based on the first resistance profile (P1).

[0083] First, the control unit (120) can be configured to determine a first resistance line (L1) for a plurality of resistors included in the first resistance profile (P1).

[0084] For example, the control unit (120) can determine the first resistance line (L1) for the first resistance profile (P1) through regression analysis. Here, the first resistance line (L1) can be linear or nonlinear.

[0085] As another example, the control unit (120) may determine the first resistance line (L1) by considering the regression analysis result of the first resistance profile (P1) together with the preset first reference resistance line. Here, the first reference resistance line is a resistance line derived from the first resistance profile (P1) of a pre-designed reference battery. That is, the reference battery is a battery pre-designed in a normal state, and the first reference resistance line is a resistance line that can be applied to a battery in a normal state. Therefore, the control unit (120) may determine the first resistance line (L1) corresponding to the first resistance profile (P1) by grafting the first reference resistance line onto the regression analysis result of the first resistance profile (P1).

[0086] Preferably, the control unit (120) can determine the first resistance line (L1) for the first resistance profile (P1) through regression analysis.

[0087] Fig. 5 is an enlarged view of the first resistance profile (P1) of Fig. 4. In the embodiment of Fig. 5, the control unit (120) can determine the first resistance line (L1) of the first resistance profile (P1).

[0088] The control unit (120) may be configured to determine a first resistance section (R1) by adding a preset resistance threshold value to the determined first resistance line (L1).

[0089] Specifically, the control unit (120) can adjust the first resistance line (L1) by adding a preset resistance threshold value to the cycle-by-cycle resistance value according to the first resistance line (L1). In addition, the control unit (120) can determine a resistance section below the adjusted first resistance line (L1) as the first resistance section (R1).

[0090] For example, in the embodiment of FIG. 5, the control unit (120) can move the first resistance line (L1) parallel along the Y-axis by adding a resistance threshold value (TH) to the cycle-by-cycle resistance value of the first resistance line (L1). In addition, the control unit (120) can determine a resistance section below the first resistance line (L1) as the first resistance section (R1).

[0091] In addition, the control unit (120) can be configured to diagnose the state of the battery by comparing the first resistance section (R1) and the target resistance.

[0092] Specifically, the control unit (120) can diagnose the state of the battery depending on whether the target resistance belongs to the first resistance section (R1).

[0093] First, if the resistance value of the target resistor is lower than or equal to the resistance value of the first resistance line (L1), the control unit (120) can determine that the target resistor belongs to the first resistance section (R1). Conversely, if the resistance value of the target resistor exceeds the resistance value of the first resistance line (L1), the control unit (120) can determine that the target resistor does not belong to the first resistance section (R1).

[0094] For example, the control unit (120) may be configured to diagnose the battery status as normal when the target resistance falls within the first resistance range (R1).

[0095] As another example, the control unit (120) may be configured to diagnose the battery status as abnormal if the target resistance does not fall within the first resistance range (R1).

[0096] Here, "normal" refers to a state in which sudden death is unlikely to occur. "Abnormal" refers to a state in which sudden death is predicted to be highly likely. In other words, a battery diagnosed as abnormal may be highly susceptible to sudden death.

[0097] In general, frequent rapid charging can lead to a higher incidence of lithium plating, a phenomenon in which lithium metal is deposited on the cathode surface, compared to regular charging. Furthermore, because lithium plating can cause internal shorts, fires, explosions, or sudden deaths, it's crucial to identify warning signs in advance.

[0098] In particular, before sudden death occurs, byproducts accumulate at the interface between the cathode and the separator, clogging the pores of the separator and depleting the electrolyte, which can significantly increase the liquid diffusion resistance of lithium ions. Since an increase in the liquid diffusion resistance is indicated by an increase in the target resistance, the control unit (120) can determine the possibility of sudden death of the battery depending on whether the target resistance falls within the first resistance range (R1).

[0099] For example, in the embodiment of FIG. 5, the target resistance of the battery from cycle C1 does not fall within the first resistance range (R1). Therefore, the control unit (120) can diagnose the state of the battery as abnormal from cycle C1.

[0100] FIG. 6 is a schematic diagram illustrating the capacity retention rate of a battery according to one embodiment of the present invention. Specifically, referring to FIG. 6 , the battery suddenly dies during the CS cycle, with the capacity retention rate plummeting to 75% or less. Since sudden death occurs suddenly, the battery diagnostic device (100) can predict and diagnose the possibility of sudden death in advance based on the behavior of the target resistance.

[0101]

[0102] Meanwhile, the control unit (120) provided in the battery diagnostic device (100) may optionally include a processor, an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, a data processing device, etc. known in the art to execute various control logics performed in the present invention. In addition, when the control logic is implemented in software, the control unit (120) may be implemented as a set of program modules. At this time, the program modules may be stored in a memory and executed by the control unit (120). The memory may be located inside or outside the control unit (120) and may be connected to the control unit (120) by various well-known means.

[0103] In addition, the battery diagnostic device (100) may further include a storage unit (130). The storage unit (130) may store data or programs required for each component of the battery diagnostic device (100) to perform operations and functions, or data generated in the process of performing operations and functions. The storage unit (130) is not particularly limited in type as long as it is a known information storage means known to be capable of recording, erasing, updating, and reading data. As an example, the information storage means may include RAM, flash memory, ROM, EEPROM, registers, etc. In addition, the storage unit (130) may store program codes defining processes executable by the control unit (120).

[0104] For example, the storage unit (130) can store various pieces of information used to diagnose the status of a battery, such as a charge profile (CP), a first resistance profile (P1), a first resistance line (L1), a resistance threshold value (TH), and a first resistance section (R1).

[0105]

[0106] Below, an embodiment in which the control unit (120) calculates the target resistance when the SOC at the start of charging of the battery is not constant for each cycle is described. That is, an embodiment in which the target resistance is calculated when the initial SOC is different from the target SOC is described.

[0107] The control unit (120) can be configured to calculate the initial resistance based on the voltage change amount and the charging current of the charging process.

[0108] Additionally, the control unit (120) may be configured to compare the initial SOC of the battery immediately before charging begins with a preset target SOC.

[0109] Specifically, the target SOC may be preset to any one of the battery's available SOC ranges. For example, the target SOC may be preset to 10% SOC.

[0110] Depending on the battery usage situation, the initial SOC of the battery just before charging begins may vary. For example, in the nth cycle, the battery may be charged from an SOC of 8%, and in the n+1th cycle, the battery may be charged from an SOC of 15%. Therefore, to more accurately calculate the target resistance, the control unit (120) may compare the initial SOC of the battery in the current cycle with the target SOC.

[0111] The control unit (120) may be configured to calculate the target resistance based on the initial resistance according to the comparison result.

[0112] If the initial SOC is equal to the target SOC, the control unit (120) may be configured to determine the initial resistance as the target resistance.

[0113] Specifically, the control unit (120) may be configured to calculate the voltage change amount by calculating the difference between the initial voltage of the battery immediately before charging begins and the voltage of the battery immediately after charging begins. Furthermore, the control unit (120) may divide the calculated voltage change amount by the charging current to calculate the initial resistance. Finally, the control unit (120) may determine the calculated initial resistance as the target resistance of the battery.

[0114] If the initial SOC is different from the target SOC, the control unit (120) may be configured to calculate the target resistance from the initial resistance based on a resistance table (T) preset to indicate the resistance ratio for each SOC.

[0115] Specifically, the control unit (120) can convert the initial resistance corresponding to the initial SOC into the target resistance corresponding to the target SOC based on a preset resistance table (T).

[0116] More specifically, the control unit (120) may be configured to calculate the total resistance for the battery by dividing the initial resistance by a resistance ratio corresponding to the initial SOC in the resistance table (T). In addition, the control unit (120) may be configured to calculate the target resistance for the battery by multiplying the calculated total resistance by a resistance ratio corresponding to the target SOC in the resistance table (T).

[0117] Fig. 7 is a schematic diagram illustrating a resistance table (T) according to one embodiment of the present invention. In the embodiment of Fig. 7, the sum of the resistance ratios of p1 to p100 is 1 or 100%.

[0118] Meanwhile, in the embodiment of Fig. 7, the resistance table (T) is set at 5% SOC intervals, but the SOC intervals in the resistance table (T) can be applied without limitation. Furthermore, the resistance ratio for an SOC (e.g., 3%) not included in the resistance table (T) can be interpolated and utilized based on the resistance ratios (p1 and p5) of adjacent SOCs (e.g., 0% and 5%).

[0119] In the embodiment of FIG. 7, it is assumed that the preset target SOC is 10%, the initial SOC of the battery is k%, and the initial resistance is R. The control unit (120) can calculate the total resistance of the battery by dividing the initial resistance R by the resistance ratio pk of the initial SOC. For example, the control unit (120) can calculate the total resistance of the battery by calculating the formula “R÷pk.” In addition, the control unit (120) can calculate the target resistance of the battery by multiplying the total resistance of the battery by the resistance ratio p10 of the target SOC. For example, the control unit (120) can calculate the target resistance of the battery by calculating the formula “R÷pk×p10.”

[0120] That is, the control unit (120) can convert the initial resistance R corresponding to the initial SOC k (%) into the target resistance (R÷pk×p10) corresponding to the target SOC 10 (%). Then, the control unit (120) can diagnose the state of the battery based on the result of comparing the target resistance and the first resistance section (R1).

[0121] A battery diagnosis device (100) according to one embodiment of the present invention calculates a target resistance by considering a situation in which the initial SOC of the battery is not constant, and can diagnose the state of the battery based on the calculated target resistance. That is, the battery diagnosis device (100) calculates the target resistance using a resistance table (T), thereby having the advantage of being able to diagnose the state of the battery even in a situation in which the initial SOC of the battery is not constant for each cycle.

[0122]

[0123] In one embodiment, the resistance table may be preset to correspond to multiple reference cycles.

[0124] For example, the resistance table can be preset every n cycles. As a specific example, the resistance table can be preset every 50 cycles.

[0125] As another example, the resistance table can be preset at M cycle intervals from the BOL cycle (e.g., the first cycle) to the EOL cycle (e.g., the Nth cycle). Preferably, M is a natural number less than N. More preferably, M is a divisor of N.

[0126] The control unit (120) may be configured to calculate a target resistance based on a resistance table corresponding to the cycle of the battery when the cycle of the battery is the same as any one of a plurality of reference cycles.

[0127] Specifically, if the cycle of the battery is included in multiple reference cycles and the initial SOC of the battery is different from the target SOC, the control unit (120) can determine a resistance table corresponding to the cycle of the battery. Then, the control unit (120) can calculate the target resistance from the initial resistance based on the determined resistance table.

[0128] For example, it is assumed that multiple reference cycles are set every 50 cycles from the first cycle. The reference cycles can be set as the first cycle, the 51st cycle, the 101st cycle, etc. If the cycle of the battery is the 51st cycle, the control unit (120) can select a resistance table corresponding to the 51st cycle from among the resistance tables corresponding to each of the multiple reference cycles. In addition, if the initial SOC of the battery is different from the target SOC, the control unit (120) can calculate the target resistance from the initial resistance based on the resistance table preset to correspond to the 51st cycle.

[0129] The control unit (120) may be configured to select a plurality of target cycles adjacent to the cycle of the battery from among the plurality of reference cycles when the cycle of the battery is different from the plurality of reference cycles.

[0130] Specifically, if the cycle of the battery is not included in the plurality of reference cycles, the control unit (120) may select some cycles that are closest to the cycle of the battery among the plurality of reference cycles as target cycles. For example, the control unit (120) may select two cycles that are closest to the cycle of the battery among the plurality of reference cycles as target cycles. In the previous embodiment, if the cycle of the battery is the 70th cycle, the control unit (120) may select the 51st cycle and the 101st cycle as target cycles.

[0131] The control unit (120) may be configured to generate a target resistance table from a resistance table corresponding to a plurality of target cycles. In addition, the control unit (120) may be configured to calculate a target resistance based on the target resistance table.

[0132] Specifically, the control unit (120) can set a representative value of the resistance ratio for each SOC based on a plurality of target cycles and generate a target resistance table including the set representative values.

[0133] For example, the control unit (120) may set a representative value based on the average value, median value, maximum value, minimum value, or a combination thereof of the resistance ratios for each SOC for multiple target cycles. Preferably, the control unit (120) may set the average value of the resistance ratios for each SOC for multiple target cycles as the representative value.

[0134] In the above embodiment, the control unit (120) assumes that the resistance ratio of the nth SOC of the 51st cycle is R51n, and the resistance ratio of the nth SOC of the 101st cycle is R101n. The control unit (120) can set the resistance ratio of the nth SOC of the target resistance table by calculating the average of R51n and R101n.

[0135] As another example, the control unit (120) can interpolate multiple target cycles to generate a target resistance table corresponding to the cycle of the battery.

[0136] Specifically, it is assumed that the cycle of the battery is cycle b, and the multiple target cycles are cycle a and cycle c. The control unit (120) can interpolate the resistance ratio by SOC of cycle a and the resistance ratio by SOC of cycle c in the ratio of "(ba)÷(ca):(cb)÷(ca)" to calculate the resistance ratio by SOC of cycle b.

[0137] For example, in the preceding embodiment, it is assumed that the cycle of the battery is the 76th cycle. The control unit (120) can calculate the resistance ratio of the nth SOC of the 76th cycle by interpolating the resistance ratio (R51n) of the nth SOC of the 51st cycle and the resistance ratio (R101n) of the nth SOC of the 101st cycle at a ratio of 1:1.

[0138] That is, the battery diagnosis device (100) has the advantage of being able to diagnose the state of the battery more accurately by calculating the target resistance using a resistance table corresponding to the cycle of the battery.

[0139]

[0140] Below, an embodiment in which the control unit (120) supplementarily diagnoses the state of the battery by further considering the sub-resistance is described.

[0141] The control unit (120) may be configured to calculate a sub-voltage change amount between the voltage of the battery immediately after charging starts in the charging profile (CP) and the voltage at the point in time when charging has proceeded for a preset period of time.

[0142] Specifically, the preset time can be determined within the time required to charge at the same charge C-RATE from the start of charging. For example, the preset time can be 30 seconds.

[0143] For example, in the embodiment of FIG. 3, the initial voltage of the battery immediately before charging begins is V1, the voltage of the battery immediately after charging begins is V2, and the voltage of the battery at the point when charging has proceeded for a preset period of time is V3. The control unit (120) can calculate the sub-voltage change amount of the battery by calculating the formula "V3-V2."

[0144] The control unit (120) can be configured to calculate the sub-resistance of the battery based on the calculated sub-voltage change amount.

[0145] For example, in the embodiments of FIGS. 2 and 3, it is assumed that the charging current for the SOC section of S1(%) to S2(%) is I. The control unit (120) can calculate a value obtained by dividing the sub-voltage change amount (V3-V2) by the charging current (I) as a sub-resistance.

[0146] The control unit (120) can be configured to diagnose the condition of the battery based on the target resistance and sub resistance.

[0147] The control unit (120) may be configured to determine the second resistance section (R2) based on a second resistance profile (P2) in which the sub-resistance of the battery calculated in the previous charging cycle is stored.

[0148] Specifically, the second resistance profile (P2) is a profile that stores the sub-resistance of the battery calculated for each past charging cycle. For example, assuming that the current cycle is the nth cycle, the sub-resistance calculated in the first to n-1th cycles may be stored in the second resistance profile (P2). Then, when the battery condition diagnosis in the nth cycle is completed, the sub-resistance calculated in the nth cycle may be stored in the second resistance profile (P2).

[0149] Fig. 8 is a diagram schematically illustrating a second resistance profile (P2) according to one embodiment of the present invention. In the embodiment of Fig. 8, the second resistance profile (P2) can be expressed as an XY graph in which the X-axis is set as a cycle and the Y-axis is set as resistance.

[0150] The control unit (120) may be configured to determine a second resistance line (L2) for a plurality of resistors included in the second resistance profile (P2).

[0151] For example, the control unit (120) can determine a second resistance line (L2) for the second resistance profile (P2) through regression analysis. Here, the second resistance line (L2) can be linear or nonlinear.

[0152] As another example, the control unit (120) may determine the second resistance line (L2) by considering the regression analysis result of the second resistance profile (P2) together with the preset second reference resistance line. Here, the second reference resistance line is a resistance line derived from the second resistance profile (P2) of the pre-designed reference battery. That is, the reference battery is a battery pre-designed in a normal state, and the second reference resistance line is a resistance line that can be applied to a battery in a normal state. Therefore, the control unit (120) may determine the second resistance line (L2) corresponding to the second resistance profile (P2) by grafting the second reference resistance line onto the regression analysis result of the second resistance profile (P2).

[0153] Preferably, the control unit (120) can determine the second resistance line (L2) for the second resistance profile (P2) through regression analysis.

[0154] Fig. 9 is an enlarged view of the second resistance profile (P2) of Fig. 8. In the embodiment of Fig. 9, the control unit (120) can determine the second resistance line (L2) of the second resistance profile (P2).

[0155] The control unit (120) may be configured to determine the second resistance section (R2) by adding a preset resistance threshold value to the determined second resistance line (L2). Specifically, the control unit (120) may determine the second resistance section (R2) by adding a resistance threshold value to the second resistance line (L2), similarly to determining the first resistance section (R1) by adding a resistance threshold value to the first resistance line (L1). Here, the resistance threshold value added to the first resistance line (L1) and the resistance threshold value added to the second resistance line (L2) may be the same or different.

[0156] For example, in the embodiment of FIG. 9, the control unit (120) can move the second resistance line (L2) parallel along the Y-axis by adding a resistance threshold value (TH) to the cycle-by-cycle resistance value of the second resistance line (L2). In addition, the control unit (120) can determine a resistance section below the second resistance line (L2) as the second resistance section (R2).

[0157] In addition, the control unit (120) can be configured to diagnose the state of the battery based on the result of comparing the first resistance section (R1) and the target resistance and the result of comparing the second resistance section (R2) and the sub resistance.

[0158] Specifically, the control unit (120) can diagnose the state of the battery depending on whether the target resistance belongs to the first resistance section (R1) and whether the sub resistance belongs to the second resistance section (R2).

[0159] First, if the resistance value of the target resistor is lower than or equal to the resistance value of the first resistance line (L1), the control unit (120) can determine that the target resistor belongs to the first resistance section (R1). Conversely, if the resistance value of the target resistor exceeds the resistance value of the first resistance line (L1), the control unit (120) can determine that the target resistor does not belong to the first resistance section (R1).

[0160] Next, if the resistance value of the sub-resistor is lower than or equal to the resistance value of the second resistance line (L2), the control unit (120) can determine that the sub-resistor belongs to the second resistance section (R2). Conversely, if the resistance value of the sub-resistor exceeds the resistance value of the second resistance line (L2), the control unit (120) can determine that the sub-resistor does not belong to the second resistance section (R2).

[0161] For example, the control unit (120) may be configured to diagnose the battery status as normal when the target resistance belongs to the first resistance section (R1) or when the sub-resistance belongs to the second resistance section (R2).

[0162] As another example, the control unit (120) may be configured to diagnose the battery status as abnormal when the target resistance does not belong to the first resistance section (R1) and the sub-resistance does not belong to the second resistance section (R2).

[0163] That is, the control unit (120) can diagnose the battery status as abnormal only when the target resistance does not belong to the first resistance section (R1) and the sub resistance does not belong to the second resistance section (R2).

[0164] For example, in the embodiments of FIGS. 5, 6, and 9, the target resistance in the C1 cycle does not belong to the first resistance section (R1), but the sub-resistance belongs to the second resistance section (R2). That is, if only the target resistance is considered, the battery state in the C1 cycle is diagnosed as an abnormal state, but if both the target resistance and the sub-resistance are considered, the battery state in the C1 cycle is diagnosed as a normal state. In addition, the target resistance in the C2 cycle does not belong to the first resistance section (R1), and the sub-resistance does not belong to the second resistance section (R2). In other words, the battery state in the C2 cycle is diagnosed as an abnormal state. In addition, sudden death occurs in the battery in the CS cycle after the C2 cycle.

[0165] When using a target resistor, the possibility of sudden battery death can be diagnosed earlier than when using a sub resistor. For example, the first cycle (e.g., C1) in which the target resistor does not fall within the first resistance range (R1) precedes the first cycle (e.g., C2) in which the sub resistor does not fall within the second resistance range (R2).

[0166] However, sudden death refers to a condition where the battery's internal resistance suddenly increases, rendering it unable to charge or discharge. Therefore, the battery's condition should be diagnosed as abnormal from a conservative and rigorous perspective. If the battery's condition is diagnosed solely based on the target resistance, it could be misdiagnosed. Furthermore, since the battery's condition is diagnosed as abnormal earlier than when considering the sub-resistance, the battery's usable lifespan is shortened.

[0167] Accordingly, the battery diagnostic device (100) according to one embodiment of the present invention can more accurately diagnose the condition of a battery by considering the sub-resistance in addition to the target resistance. Furthermore, the battery diagnostic device (100) can increase the expected life of the battery by considering both the target resistance and the sub-resistance.

[0168]

[0169] The battery diagnosis device (100) according to the present invention can be applied to a BMS (Battery Management System). That is, the BMS according to the present invention can include the battery diagnosis device (100) described above. In this configuration, at least some of the components of the battery diagnosis device (100) can be implemented by supplementing or adding to the functions of the components included in a conventional BMS. For example, the profile acquisition unit (110), the control unit (120), and the storage unit (130) of the battery diagnosis device (100) can be implemented as components of the BMS.

[0170] In addition, the battery diagnostic device (100) according to the present invention may be equipped in a battery pack (10). That is, the battery pack according to the present invention may include the battery diagnostic device (100) described above and one or more battery cells. In addition, the battery pack may further include electrical components (relays, fuses, etc.) and a case, etc.

[0171] FIG. 10 is a schematic drawing of a battery pack according to another embodiment of the present invention.

[0172] The positive terminal of the battery (11) can be connected to the positive terminal (P+) of the battery pack (10), and the negative terminal of the battery (11) can be connected to the negative terminal (P-) of the battery pack (10).

[0173] The measuring unit (12) can be connected to a first sensing line (SL1), a second sensing line (SL2), and a third sensing line (SL3). Specifically, the measuring unit (12) can be connected to a positive terminal of the battery (11) through the first sensing line (SL1), and can be connected to a negative terminal of the battery (11) through the second sensing line (SL2). The measuring unit (12) can measure the voltage of the battery (11) based on the voltage measured at each of the first sensing line (SL1) and the second sensing line (SL2).

[0174] And, the measuring unit (12) can be connected to the current measuring unit (A) through the third sensing line (SL3). For example, the current measuring unit (A) can be an ammeter or a shunt resistor capable of measuring the charging current and discharging current of the battery (11). The measuring unit (12) can measure the charging current of the battery (11) through the third sensing line (SL3) to calculate the charging amount. In addition, the measuring unit (12) can measure the discharging current of the battery (11) through the third sensing line (SL3) to calculate the discharging amount.

[0175] For example, the profile acquisition unit (110) can receive battery information about the voltage and current of the battery from the measurement unit (12). Then, the profile acquisition unit (110) can generate a charging profile (CP) based on the battery information.

[0176] As another example, the profile acquisition unit (110) can receive a charging profile (CP) from the measurement unit (12).

[0177] An external device may be connected to the positive terminal (P+) and negative terminal (P-) of the battery pack (10). For example, the external device may be a charging device or a load. In addition, the positive terminal of the battery (11), the positive terminal (P+) of the battery pack (10), the external device, the negative terminal (P-) of the battery pack (10), and the negative terminal of the battery (11) may be electrically connected.

[0178]

[0179] Fig. 11 is a schematic drawing of a vehicle (1) according to another embodiment of the present invention.

[0180] Referring to FIG. 11, a battery pack (10) according to an embodiment of the present invention may be included in a vehicle (1), such as an electric vehicle (EV) or a hybrid vehicle (HV). In addition, the battery pack (10) may drive the vehicle (1) by supplying power to a motor through an inverter provided in the vehicle (1). Here, the battery pack (10) may include a battery diagnostic device (100). That is, the vehicle (1) may include a battery diagnostic device (100). In this case, the battery diagnostic device (100) may be an on-board device included in the vehicle (1).

[0181]

[0182] FIG. 12 is a diagram schematically illustrating a battery diagnosis method according to another embodiment of the present invention.

[0183] Referring to FIG. 12, the battery diagnosis method may include a profile acquisition step (S100), a voltage change calculation step (S200), a target resistance calculation step (S300), and a diagnosis step (S400).

[0184] Preferably, each step of the battery diagnosis method can be performed by the battery diagnosis device (100). In the following, for convenience of explanation, any content that overlaps with the previously described content will be omitted or briefly described.

[0185] The profile acquisition step (S100) is a step of acquiring a charging profile (CP) that indicates a voltage change of the battery during the charging process, and can be performed by the profile acquisition unit (110).

[0186] For example, the profile acquisition unit (110) can directly receive the charging profile (CP) of the battery from the outside. That is, the profile acquisition unit (110) can acquire the charging profile (CP) by being connected to the outside via wire and / or wirelessly and receiving the charging profile (CP).

[0187] As another example, the profile acquisition unit (110) can receive battery information regarding the battery's voltage and SOC. Furthermore, the profile acquisition unit (110) can generate a charging profile (CP) based on the received battery information. That is, the profile acquisition unit (110) can acquire a charging profile (CP) by directly generating the charging profile (CP) based on the battery information.

[0188] The voltage change calculation step (S200) is a step for calculating the voltage change of the battery at the start of charging of the charging profile (CP), and can be performed by the control unit (120).

[0189] For example, the control unit (120) may be configured to calculate the voltage change amount by calculating the difference between the initial voltage of the battery just before charging begins and the voltage of the battery immediately after charging begins.

[0190] The target resistance calculation step (S300) is a step of calculating the target resistance of the battery based on the calculated voltage change amount and the initial SOC of the battery at the start of charging, and can be performed by the control unit (120).

[0191] The control unit (120) can calculate the target resistance in a different manner when the initial SOC is different from the target SOC.

[0192] The control unit (120) may be configured to calculate the initial resistance based on the voltage change amount and the charging current during the charging process. Specifically, the control unit (120) may be configured to determine the initial resistance as the target resistance when the initial SOC is equal to a preset target SOC. Conversely, the control unit (120) may be configured to calculate the target resistance from the initial resistance based on a resistance table preset to indicate a resistance ratio for each SOC when the initial SOC is different from the target SOC.

[0193] For example, in the embodiments of FIGS. 2 and 3, it is assumed that the charging current for the SOC section of S1(%) to S2(%) is I. The control unit (120) can calculate the initial resistance as a value obtained by dividing the voltage change amount (V2-V1) by the charging current (I). In addition, the control unit (120) can determine the initial resistance as the target resistance or calculate the target resistance based on the initial resistance, depending on whether the initial SOC of the battery is the same as the target SOC.

[0194] The diagnosis step (S400) is a step for diagnosing the state of the battery by comparing the target resistance with the first resistance profile (P1) in which the target resistance of the battery calculated in the previous charging cycle is stored, and can be performed by the control unit (120).

[0195] The control unit (120) may be configured to determine the first resistance section (R1) based on the first resistance profile (P1).

[0196] In addition, the control unit (120) may be configured to diagnose the state of the battery by comparing the first resistance section (R1) with the target resistance. For example, the control unit (120) may be configured to diagnose the state of the battery as normal when the target resistance falls within the first resistance section (R1). As another example, the control unit (120) may be configured to diagnose the state of the battery as abnormal when the target resistance does not fall within the first resistance section (R1).

[0197]

[0198] The embodiments of the present invention described above are not implemented only through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

[0199] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0200] In addition, the present invention described above is not limited to the above-described embodiments and the attached drawings, and all or part of each embodiment may be selectively combined and configured so that various modifications can be made, as those skilled in the art can make various substitutions, modifications, and changes within the scope of the technical idea of ​​the present invention.

[0201] (Explanation of symbols)

[0202] 1: Car

[0203] 10: Battery pack

[0204] 11: Battery

[0205] 12: Measurement section

[0206] 100: Battery Diagnostic Device

[0207] 110: Profile acquisition section

[0208] 120: Control unit

[0209] 130: Storage

Claims

1. A profile acquisition unit configured to acquire a charging profile indicating a voltage change of a battery during a charging process; and A battery diagnosis device comprising a control unit configured to calculate a voltage change amount of the battery at the start point of charging of the charging profile, calculate a target resistance of the battery based on the calculated voltage change amount and the initial SOC of the battery at the start point of charging, and diagnose the state of the battery by comparing the target resistance with a first resistance profile in which the target resistance of the battery calculated in a previous charging cycle is stored.

2. In paragraph 1, The above control unit, Calculate the initial resistance based on the voltage change amount and the charging current of the charging process, If the initial SOC is equal to the preset target SOC, the initial resistance is determined as the target resistance, A battery diagnostic device configured to calculate the target resistance from the initial resistance based on a resistance table preset to indicate a resistance ratio by SOC when the initial SOC is different from the target SOC.

3. In paragraph 2, The above resistance table is preset to correspond to multiple reference cycles, The above control unit, A battery diagnostic device configured to calculate the target resistance based on a resistance table corresponding to the cycle of the battery, when the cycle of the battery is the same as any one of the plurality of reference cycles.

4. In paragraph 3, The above control unit, A battery diagnostic device configured to select a plurality of target cycles adjacent to the cycle of the battery from among the plurality of reference cycles when the cycle of the battery is different from the plurality of reference cycles, generate a target resistance table from a resistance table corresponding to the plurality of target cycles, and calculate the target resistance based on the target resistance table.

5. In paragraph 2, The above control unit, A battery diagnostic device configured to calculate the total resistance for the battery by dividing the initial resistance by a resistance ratio corresponding to the initial SOC in the resistance table, and to calculate the target resistance for the battery by multiplying the total resistance by a resistance ratio corresponding to the target SOC in the resistance table.

6. In paragraph 1, The above control unit, A battery diagnostic device configured to determine a first resistance section based on the first resistance profile and to diagnose the state of the battery by comparing the first resistance section with the target resistance.

7. In paragraph 6, The above control unit, A battery diagnostic device configured to determine a first resistance line for a plurality of resistances included in the first resistance profile, and to determine the first resistance section by adding a preset resistance threshold value to the determined first resistance line.

8. In paragraph 6, The above control unit, If the target resistance falls within the first resistance range, the battery's status is diagnosed as normal, A battery diagnostic device configured to diagnose the state of the battery as abnormal if the target resistance does not fall within the first resistance range.

9. In paragraph 6, The above control unit, A battery diagnostic device configured to calculate a sub-voltage change amount between the voltage of the battery immediately after the charging starts in the charging profile and the voltage at a point in time when the charging has been performed for a preset period of time, calculate a sub-resistance of the battery based on the calculated sub-voltage change amount, and diagnose the state of the battery based on the target resistance and the sub-resistance.

10. In paragraph 9, The above control unit, A battery diagnostic device configured to determine a second resistance section based on a second resistance profile in which the sub-resistance of the battery calculated in the previous charging cycle is stored, and to diagnose the state of the battery based on a result of comparing the first resistance section with the target resistance and a result of comparing the second resistance section with the sub-resistance.

11. In paragraph 10, The above control unit, A battery diagnostic device configured to determine a second resistance line for a plurality of resistances included in the second resistance profile, and to determine the second resistance section by adding a preset resistance threshold value to the determined second resistance line.

12. In paragraph 10, The above control unit, When the target resistance belongs to the first resistance section or the sub resistance belongs to the second resistance section, the state of the battery is diagnosed as normal, A battery diagnostic device configured to diagnose the state of the battery as abnormal when the target resistance does not belong to the first resistance section and the sub resistance does not belong to the second resistance section.

13. In paragraph 1, The above control unit, A battery diagnostic device configured to calculate the voltage change amount by calculating the difference between the initial voltage of the battery immediately before the charging starts and the voltage of the battery immediately after the charging starts.

14. A battery pack comprising a battery diagnostic device according to any one of claims 1 to 13.

15. A profile acquisition step for acquiring a charging profile representing the voltage change of the battery during the charging process; A voltage change calculation step for calculating the voltage change of the battery at the start of charging of the above charging profile; A target resistance calculation step for calculating the target resistance of the battery based on the calculated voltage change amount and the initial SOC of the battery at the start of the charging; and A battery diagnosis method comprising a diagnosis step of diagnosing the condition of the battery by comparing the target resistance of the battery with a first resistance profile in which the target resistance of the battery is stored, calculated from a previous charging cycle.

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