Battery pack determination method and vehicle manufacturing method

Abstract

To provide a new determination method to determine whether a battery pack is normal.SOLUTION: The determination method for determining whether a battery pack is normal has the steps of: measuring changes over time of at least one of the temperatures and the output voltage of the battery pack while heating the battery pack, and based on the measured changes over time, determining whether the battery pack is normal. This determination method allows accurate determination of whether the battery pack is normal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a method for determining a battery pack.

[0002] Patent Document 1 discloses a method for determining whether a battery cell is genuine or non-genuine. In this method, the internal resistance of the battery cell at the time of shipment is calculated based on the change in the charging rate of the battery cell associated with the number of charge / discharge cycles of the battery cell, and whether the battery cell is genuine or non-genuine is determined based on the calculated internal resistance at the time of shipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-114437 A Summary of the Invention [Problem to be solved by the invention]

[0004] The method of determining whether a battery pack is normal or not may result in erroneous determination if a non-genuine product has an internal resistance similar to that of a genuine product. In this specification, a new method of determining whether a battery pack is normal or not is proposed. [Means for solving the problem]

[0005] The present specification discloses a method for determining whether a battery pack is normal or not, the method comprising the steps of measuring a change over time in at least one of a temperature and an output voltage of the battery pack while heating the battery pack, and determining whether the battery pack is normal or not based on the measured change over time.

[0006] Note that determining whether the battery pack is normal or not may also be determining whether the battery pack is a genuine product or a non-genuine product.

[0007] If there is an abnormality in the electrodes or electrolyte inside the battery pack, the battery pack may generate heat by itself when the battery pack is heated. Therefore, by measuring the change in temperature of the battery pack over time while heating the battery pack, it is possible to determine whether the battery pack is normal or not. Furthermore, if there is an abnormality in the electrodes, electrolyte, or separator inside the battery pack, the output voltage of the battery pack may decrease when the battery pack is heated. Therefore, by measuring the change in output voltage of the battery pack over time while heating the battery pack, it is possible to determine whether the battery pack is normal or not. In this way, according to the determination method of item 1, it is possible to determine whether the battery pack is normal or not. [Brief description of the drawings]

[0008] [Figure 1] 6 is a graph showing changes over time in the temperature inside the furnace and the temperature of the battery pack in the determination process. [Diagram 2] 6 is a graph showing the change over time in the output voltage of the battery pack in the determination process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Following on from item 1 above, the features of the technology disclosed in this specification are listed below. (Item 2) 2. The method according to item 1, wherein in the step, an environmental temperature around the battery pack is controlled to a constant value. (Item 3) 3. The method according to claim 1, wherein, in the step, the battery pack is determined to be abnormal when an amount of temperature rise of the battery pack relative to an ambient temperature around the battery pack exceeds a reference value. (Item 4) 4. The method according to any one of items 1 to 3, wherein, in the step, it is determined that the battery pack is abnormal when the amount of decrease in the output voltage of the battery pack exceeds a reference value. (Item 5) A step of carrying out the determination method according to any one of items 1 to 4; a step of mounting the battery pack determined to be normal in the determination method on a vehicle; A method for manufacturing a vehicle having the above structure.

[0010] According to the determination method of item 2 above, a more accurate determination is possible.

[0011] According to the determination method of item 3 above, an abnormality in the battery pack can be accurately detected.

[0012] According to the determination method of item 4 above, an abnormality in the battery pack can be accurately detected. EXAMPLES

[0013] In the determination method of the embodiment described below, it is determined whether a target battery pack is a genuine product (i.e., a product supplied by a manufacturer legitimately) or a non-genuine product. This determination method has a determination step of measuring the temperature and output voltage of the battery pack over time while heating the battery pack. In the determination step, the battery pack is placed in a furnace, and the temperature inside the furnace (i.e., the temperature of the air inside the furnace) is changed as shown in FIG. 1. The temperature inside the furnace corresponds to the environmental temperature around the battery pack. Here, the temperature inside the furnace is increased so that the temperature inside the furnace reaches temperature T0 (e.g., 110°C) at time t1, and after time t1, the temperature inside the furnace is maintained at temperature T0 (i.e., a constant value) for a predetermined time (e.g., 3 hours). The temperature of the battery pack is detected by a temperature sensor. The output voltage of the battery pack is detected by connecting a voltage sensor to the output terminal of the battery pack inside the furnace via wiring.

[0014] FIG. 1 shows the change in temperature of battery packs A to C over time during the determination process. Battery pack A is a genuine product, and battery packs B and C are non-genuine products. The electrodes and electrolyte inside battery pack A, which is a genuine product, are thermally stable, and self-heating hardly occurs in battery pack A. Therefore, the temperature of battery pack A is almost the same as the temperature inside the furnace. In contrast, in battery pack B, which is a non-genuine product, at least one of the electrodes and electrolyte reacts due to heating, causing self-heating. Therefore, the temperature of battery pack B rises significantly above temperature T0 after time t1. In addition, in battery pack C, which is a non-genuine product, thermal runaway occurs due to self-heating. Therefore, the temperature of battery pack C rises to an extremely high temperature after time t1. In the determination process, the increase ΔT of the temperature of the battery pack relative to the furnace temperature T0 is monitored, and when the increase ΔT exceeds a reference value ΔTth, the battery pack is determined to be a non-genuine product, and when the increase Δ does not exceed the reference value ΔTth, the battery pack is determined to be a genuine product. In Fig. 1, the temperature rise ΔT of battery pack A has never exceeded the reference value ΔTth, so battery pack A is determined to be genuine. Also, in Fig. 1, the temperature rise Δ of battery packs B and C exceeds the reference value ΔTth, so battery packs B and C are determined to be non-genuine. In this way, the thermal stability of a battery pack differs depending on whether it is genuine or non-genuine, so by measuring the change in temperature of the battery pack over time while heating it, it is possible to accurately determine whether the battery pack is genuine or non-genuine.

[0015] FIG. 2 shows the change over time in the output voltage of the battery packs A to C during the determination process. Since the electrodes, electrolyte, and separator inside the battery pack A are thermally stable, the amount of decrease ΔV in the output voltage when the battery pack A is heated (i.e., the amount of decrease from the initial value V0 of the output voltage) is small. That is, the output voltage of the battery pack A does not change much between when it is heated and the initial value. In contrast, the electrodes, electrolyte, and separator inside the battery pack B are thermally unstable. Therefore, when the battery pack B is heated, the output voltage of the battery pack B decreases due to the deterioration of the separator causing self-discharge inside the battery pack B, or the internal resistance of the battery pack B changing due to the deterioration of the electrodes or electrolyte. Therefore, as shown in FIG. 2, the amount of decrease ΔV in the output voltage of the battery pack B is large. Furthermore, when the battery pack C is heated, the output voltage of the battery pack C decreases significantly due to the deterioration of the internal electrodes, electrolyte, and separator. In the determination step, the amount of decrease ΔV of the output voltage of the battery pack is monitored, and when the amount of decrease ΔV exceeds a reference value ΔVth (i.e., when the output voltage falls below V0-ΔVth), the battery pack is determined to be a non-genuine product, and when the amount of decrease ΔV does not exceed the reference value ΔVth, the battery pack is determined to be a genuine product. In FIG. 2, the amount of decrease ΔV of the output voltage of battery pack A has never exceeded the reference value ΔVth, so battery pack A is determined to be a genuine product. Also, in FIG. 2, the amount of decrease ΔV of the output voltage of battery packs B and C exceeds the reference value ΔVth, so battery packs B and C are determined to be non-genuine products. In this way, the stability of the output voltage when the battery pack is heated differs depending on whether it is a genuine product or a non-genuine product, so by measuring the change over time in the output voltage of the battery pack while heating the battery pack, it is possible to accurately determine whether the battery pack is genuine or non-genuine.

[0016] In the above embodiment, the change over time of both the temperature and the output voltage of the battery pack was measured while the battery pack was heated. However, the change over time of only one of the temperature and the output voltage of the battery pack may be measured while the battery pack is heated. In addition, the determination method disclosed in this specification may be combined with another determination method to more accurately determine whether the product is genuine or non-genuine.

[0017] In the above embodiment, the environmental temperature of the battery pack is maintained at a constant temperature (i.e., temperature T0) after time t1. By maintaining the environmental temperature at a constant temperature in this manner, it is possible to accurately determine whether the battery pack is genuine or non-genuine. However, in other embodiments, the environmental temperature of the battery pack may be changed.

[0018] In the above-described embodiment, it is determined whether the battery pack is genuine or non-genuine. However, according to this determination method, it is also possible to determine whether or not there is an abnormality in a genuine battery pack. For example, even if the battery pack is genuine, an abnormality may occur inside the battery pack due to improper use. In such a case, according to the determination method disclosed in this specification, it is possible to detect an abnormality in a genuine battery pack.

[0019] In addition, after it is determined that the battery pack is normal by the above-mentioned battery pack determination method, the battery pack may be mounted on a vehicle. Since it is difficult to heat the battery pack after it is mounted on the vehicle, the determination method disclosed in this specification can be performed before the battery pack is mounted on the vehicle.

[0020] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility.

Claims

1. A method for determining whether a battery pack is normal, comprising the steps of: a step of measuring a change over time in at least one of a temperature and an output voltage of the battery pack while heating the battery pack, and determining whether or not the battery pack is normal based on the measured change over time; In the step, when an amount of temperature rise of the battery pack relative to an environmental temperature around the battery pack exceeds a reference value, the battery pack is determined to be abnormal. Judgment method.

2. A step of carrying out the determination method according to claim 1; a step of mounting the battery pack determined to be normal in the determination method on a vehicle; A method for manufacturing a vehicle having the above structure.

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