A method and device for detecting over-temperature of a bifurcated tab

Abstract

The application belongs to the technical field of power batteries, and relates to a method and device for overcurrent temperature rise detection of bifurcated connecting pieces. In view of the problem that the overcurrent temperature rise detection method for power batteries in the prior art cannot detect bifurcated connecting pieces, the application provides a method for overcurrent temperature rise detection of bifurcated connecting pieces, which can be suitable for accurate measurement of overcurrent temperature rise of bifurcated connecting pieces. The application also provides a device for overcurrent temperature rise detection of bifurcated connecting pieces, which solves the technical problem that the two ends of bifurcated connecting pieces are different in area, and the two ends of the overcurrent connecting piece cannot be simultaneously connected to the detection device under the condition that the overcurrent areas of the two ends are the same, thereby causing inaccurate detection data.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power batteries, and particularly relates to a method and device for detecting overcurrent temperature rise of bifurcated connecting pieces. BACKGROUND

[0002] In the field of power batteries, battery temperature is directly related to battery safety. When the battery temperature exceeds a certain limit, the battery life and performance are reduced, and safety accidents such as combustion and explosion are prone to occur. Therefore, at the beginning of battery design, it is necessary to ensure that the temperature performance of the battery in all aspects meets the indicators. Among them, the overcurrent capacity of the power battery structural part is a very important design parameter, especially the connecting piece connecting the cell winding and the external terminal. The connecting piece conducts the power of the power battery to the outside for use by other devices. The design and verification of the overcurrent capacity of the connecting piece is very important, and even directly related to the performance and safety of the whole power battery.

[0003] For a general rectangular connecting piece, the current at both ends can be tested. Or through the detection of the temperature of other components such as the pole during the overcurrent process, such as Chinese Utility Model Patent No. CN203983423U, Application Date: May 30, 2014, and the name is "Lithium battery shell cover plate connecting piece and pole overcurrent temperature rise testing device", the disclosed scheme includes a heat insulation box, a spring support table for clamping the battery shell cover plate to be tested to prevent it from turning is installed in the heat insulation box, the connecting piece and the pole of the battery shell cover plate to be tested are electrically connected through a wire harness to a battery test cabinet placed outside the heat insulation box which can deliver different sizes of current, and the gasket placed on the connecting piece of the battery shell cover plate to be tested is electrically connected with the temperature acquisition instrument through a platinum wire thermocouple. The scheme is suitable for testing the overcurrent temperature rise of the square lithium battery shell cover plate connecting piece and the pole, and can also be used for testing the overcurrent temperature rise of the cylindrical lithium battery shell cover plate connecting piece and the pole, but it is not suitable for detecting the overcurrent temperature rise of the bifurcated connecting piece. In the method, there are reports on the detection of current collectors, such as Chinese Invention Patent Application Publication No. CN108896923A, Application Date: June 28, 2018, and the name is "Lithium battery current collector overcurrent capacity testing device and testing method", the disclosed method includes a testing device and a current collector. The method analyzes and determines the overcurrent capacity of the current collector by monitoring the surface temperature of the current collector under different currents, but it cannot be directly applied to the connecting piece.

[0004] With the increase of the energy density requirement of power battery, the capacity of power battery is also increased, and the power battery becomes wider and wider, and the bifurcated connecting piece becomes more and more the choice of large-capacity battery. For the bifurcated connecting piece used for large-capacity battery, because the cross-sectional area of the two ends of the connecting piece is greatly different, the current cannot be directly held at the two ends of the bifurcated connecting piece, so that it cannot be tested. Or after the single bifurcated part is bolted, the current is held, but because the size of the bifurcated part is small, the relative value of the contact resistance after the bolt connection is large, so that the test result is very inaccurate. That is, for the bifurcated connecting piece, the areas of the two ends are different, and it is difficult to simultaneously ensure that the two ends are connected to the test equipment under the condition that the connecting piece has the same connection overcurrent area. In actual situation, the test error caused by the excessively large contact resistance is very high, so that the test result is not reliable. Therefore, the new energy industry needs a device that can accurately test the overcurrent temperature rise of the connecting piece for verifying the design risk of the connecting piece. SUMMARY

[0005] 1. Technical problems to be solved by the application

[0006] The application belongs to the technical field of power batteries, and relates to a method and a device for detecting the overcurrent temperature rise of a bifurcated connecting piece. In view of the problem in the prior art that the overcurrent temperature rise detection method for power batteries cannot detect bifurcated connecting pieces, the application provides a method for detecting the overcurrent temperature rise of a bifurcated connecting piece, which can be used for accurate measurement of the overcurrent temperature rise of a bifurcated connecting piece. The application also provides a device for detecting the overcurrent temperature rise of a bifurcated connecting piece, which solves the technical problem that the two ends of a bifurcated connecting piece have different areas, and the two ends of the overcurrent connecting piece cannot be simultaneously connected to the detection device under the condition that the two ends have the same overcurrent area, resulting in inaccurate detection data.

[0007] 2. Technical solutions

[0008] To achieve the above-mentioned purpose, the technical solutions provided are as follows:

[0009] The method for detecting the overcurrent temperature rise of a bifurcated connecting piece comprises bifurcated connecting pieces with bifurcated parts and head parts, two bifurcated connecting pieces form a detection sample, and the detection sample has two head parts away from each other and two bifurcated parts close to each other.

[0010] The method comprises the following steps:

[0011] S1, waiting for the ambient temperature and the detection sample to reach an initial temperature;

[0012] S2, supplying power to the detection sample at a C times current of X;

[0013] S3: If the sample reaches the cutoff temperature, the detection will stop; if the sample does not reach the cutoff temperature, the power will continue to be supplied until the sample reaches the test time, at which point the detection will stop.

[0014] Furthermore, different currents of X*C are passed through the detection sample, with an energizing time Y of 3600 / X seconds.

[0015] Furthermore, the multiplier X is 0.33C, 0.5C, 1C, 2C, or 3C.

[0016] An apparatus for detecting overcurrent temperature rise of bifurcated connecting pieces, wherein the bifurcated portions of the two bifurcated connecting pieces overlap or align symmetrically on an axis along the direction of the head and the bifurcated portion.

[0017] Furthermore, the two forked connecting pieces are connected by bolts; the forked portion is provided with a tail connecting hole that mates with the bolt.

[0018] Furthermore, the two forked connecting pieces are welded together by a welding part; the welding part is disposed on the surface of the forked connecting pieces.

[0019] Furthermore, the two forked connecting pieces are welded together by a welding part; the welding part is located at the end of the forked portion, such that the two forked connecting pieces do not have overlapping projections in the direction perpendicular to the axis.

[0020] Furthermore, it also includes a temperature sensing wire connection portion disposed on the surface of the forked connecting piece.

[0021] Furthermore, there are six temperature sensing wire connection parts, evenly distributed around the groove formed by the two bifurcated parts.

[0022] Furthermore, the detection component includes a power connector, a connecting part, a temperature sensing wire, a testing device, and a data logger; the power connector and the head are connected through the connecting part, and the testing device is connected to the power connector; the temperature sensing wire is connected to the temperature sensing wire connecting part, and the data logger is connected to the temperature sensing wire.

[0023] 3. Beneficial effects

[0024] Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects:

[0025] (1) The application discloses a method for detecting overcurrent temperature rise of bifurcated connecting pieces, which comprises bifurcated connecting pieces with bifurcated parts and head parts, two bifurcated connecting pieces form a detection sample, the detection sample has two head parts away from each other and two bifurcated parts close to each other, different X current is passed through the detection sample, and C current of different X is passed through according to the time Y of 3600 / X seconds, so that the detection is simple and easy to implement, and data is accurate.

[0026] (2) The application discloses a device for detecting overcurrent temperature rise of bifurcated connecting pieces, bifurcated parts of two bifurcated connecting pieces are symmetrically overlapped or aligned on an axis along the direction of the head part and the bifurcated part, and can be used for detecting overcurrent temperature rise of bifurcated connecting pieces of different sizes. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a first perspective schematic view of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 1.

[0028] Figure 2 It is a first perspective schematic view of bifurcated connecting pieces according to example 1.

[0029] Figure 3 It is a first perspective schematic view of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 2.

[0030] Figure 4 It is a first perspective schematic view of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 3.

[0031] Figure 5 It is a second perspective schematic view of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 3.

[0032] Figure 6 It is a schematic view of temperature sensing line layout and temperature sensing line connection of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 1.

[0033] Figure 7 It is a schematic view of temperature sensing line layout and temperature sensing line connection of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 2.

[0034] Figure 8 It is a schematic view of temperature sensing line layout and temperature sensing line connection of a device for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 3.

[0035] Figure 9 It is a process flow schematic view of a method for detecting overcurrent temperature rise of bifurcated connecting pieces according to example 4.

[0036] Figure 10A flow diagram of a method for testing the temperature rise of a bifurcated tab for the embodiment 4.

[0037] Figure 11 A photograph of the device prepared for the embodiment 1.

[0038] Figure 12 A photograph of the device prepared for the embodiment 2.

[0039] Figure 13 A photograph of the device prepared for the embodiment 3.

[0040] Figure 14 A temperature distribution cloud chart of the tab at a certain magnification in the device prepared for the embodiment 2.

[0041] Figure 15 A temperature distribution cloud chart of the tab at a certain magnification in the device prepared for the embodiment 3.

[0042] Figure 16 A photograph of the device (bolt connection) prepared for the embodiment 4 from the first perspective.

[0043] Figure 17 A photograph of the device (bolt connection) prepared for the embodiment 4 from the second perspective.

[0044] Figure 18 A photograph of the device (bolt connection) prepared for the embodiment 4 from the third perspective.

[0045] Figure 19 A photograph of the device (bolt connection) prepared for the embodiment 4 from the third perspective.

[0046] In the figure:

[0047] 1: test sample; 11, 12: bifurcated tab; 13: bolt; 14: welding part;

[0048] 111: surface; 112: head connecting hole; 113: tail connecting hole; 114: bifurcated part; 115: head;

[0049] 2: power supply connector;

[0050] 3: connecting part;

[0051] 4: temperature sensing wire. DETAILED DESCRIPTION

[0052] The application is further described below in conjunction with specific embodiments.

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Example 1

[0055] This embodiment provides a device for detecting overcurrent temperature rise in a bifurcated connecting piece, such as... Figure 1 As shown, the sample includes a test sample 1, which is composed of two forked connecting pieces 11 and 12. Figure 2 As shown, the bifurcated connecting pieces 11 and 12 include a head 115 and a bifurcated portion 114. The bifurcated portions 114 of the two bifurcated connecting pieces 11 and 12 are symmetrically overlapped or aligned on the axis along the direction of the head 115 and the bifurcated portion 114. The overlap mentioned in this embodiment refers to the relative overlap of the bifurcated portions 114 of the two bifurcated connecting pieces 11, rather than one bifurcated portion 114 superimposed on the other bifurcated portion 114, forming a situation where the two layers of projections completely overlap. In this embodiment, the two bifurcated portions 114 overlap. When overlapping, in the direction perpendicular to the axis, the projections of the two bifurcated portions 114 overlap, and 0 < overlapping area ≤ area of ​​the bifurcated portion 114. In practical scenarios, the overlapping area should not be too small. If the overlapping area is too small, the relative value of the contact internal resistance is large, and the detection result is inaccurate. If the overlapping area is too large, the area that needs to be leveled in the overlapping part is larger, resulting in a longer processing time and reduced efficiency.

[0056] In this embodiment, the two forked connecting pieces 11 and 12 are connected by bolts 13. The forked portion 114 is provided with a tail connecting hole 113 that mates with the bolts 13. The two forked connecting pieces 11 and 12 are identical, and the bolts 13 can connect the two forked connecting pieces 11 and 12 into a single test sample 1 through the tail connecting hole 113.

[0057] This embodiment also includes temperature sensing wire connection portions disposed on the surface 111 of the bifurcated connecting pieces 11 and 12, allowing the temperature sensing wires of the detection components to be easily and quickly connected to the detection sample 1. In this embodiment, there are six temperature sensing wire connection portions, evenly distributed around the groove formed by the two bifurcated portions 114. In practical applications, if it is necessary to detect the temperature of the middle or end of the bifurcated connecting pieces 11 and 12, it is only necessary to connect the temperature sensing wire to the corresponding temperature sensing wire connection portion. If it is necessary to detect the average temperature of the middle and end, it is only necessary to connect the two temperature sensing wires to the middle and end of the temperature to be detected, respectively, to measure the average temperature.

[0058] This embodiment also includes detection components, which include a power connector 2, a connecting part 3, a temperature sensing wire, a testing device, and a data logger. The power connector 2 and the head 115 are connected through the connecting part 3, and the testing device is connected to the power connector 2. The temperature sensing wire is connected to the temperature sensing wire connecting part, and the data logger is connected to the temperature sensing wire. The connecting part 3 is a bolt and nut structure, installed in the head connecting hole 112 on the head 115.

[0059] In this embodiment, the processing of sample 1 requires the preparation of three connecting holes, followed by flattening the bifurcated connecting pieces 11 and 12. Similar to Embodiment 1, in practical applications, the overlapping area should not be too small. If the overlapping area is too small, the relative value of the contact resistance is relatively large, leading to inaccurate detection results. Conversely, if the overlapping area is too large, the area requiring flattening of the overlapping portion is larger, resulting in longer processing time and reduced efficiency.

[0060] In this embodiment, the surfaces of the forked connecting pieces 11 and 12 are polished to increase the contact area with the connecting part 3 and the power connector 2, thereby reducing the contact resistance. The surfaces of the forked connecting pieces 11 and 12 are also wiped with alcohol to remove oil and impurities, preventing increased contact resistance due to poor connection or welding.

[0061] When the forked connecting pieces 11 and 12 are connected, solder paste is applied to the area where they connect with the connecting part 3 to increase the effective connection area and reduce the contact resistance. In this embodiment, the bolt connection requires the bolt 13 to be torqued.

[0062] Example 2

[0063] This embodiment provides a device for detecting overcurrent temperature rise in a bifurcated connecting piece, such as... Figure 3 As shown, basically the same as in Embodiment 1, the two forked portions 114 of the two forked connecting pieces 11 and 12 overlap symmetrically on the axis along the direction of the head 115 and the forked portion 114. The overlap mentioned in this embodiment refers to the relative overlap of the forked portions 114 of the two forked connecting pieces 11, rather than one forked portion 114 superimposed on the other forked portion 114, forming a situation where the two layers of projection completely overlap.

[0064] The difference lies in that the two forked connecting pieces 11 and 12 are welded together by a welding part 14, which is disposed on the surface 111 of the forked connecting pieces 11 and 12. In this embodiment, the processing of the test sample 1 only requires machining the head connecting hole 112 at the head 115 and then leveling it. For the welded connecting pieces of this application, it is necessary to check the weld surface quality and measure parameters such as the weld area, perimeter, and weld width of the contact surface.

[0065] Example 3

[0066] A device for detecting the temperature rise of bifurcated connecting pieces in the flow, as shown in Figure 4 The two bifurcated parts 114 of the two bifurcated connecting pieces 11, 12 are symmetrically aligned along the axis in the direction of the head part 115 and the bifurcated part 114. The alignment of the bifurcated connecting pieces 11 in this embodiment refers to the alignment of the bifurcated parts 114 of the two bifurcated connecting pieces 11, not the case where one bifurcated part 114 is superimposed on the other bifurcated part 114 to form a two-layer projection alignment. The two bifurcated connecting pieces 11, 12 are connected by a welding part 14, which is arranged at the end of the bifurcated connecting piece 11, 12, so that the two bifurcated connecting pieces 11, 12 do not have overlapping projections in the direction perpendicular to the axis. The bifurcated connecting pieces 11, 12 of this embodiment do not have tail connecting holes 113, and the bifurcated connecting pieces 11, 12 are integrally connected after being mirror-symmetrically connected.

[0067] In some embodiments, the bifurcated connecting pieces 11, 12 are integrally formed by stamping, and during processing, a drawing of the mirror image structure of a single bifurcated connecting piece 11, 12 is designed according to the structure of the single bifurcated connecting piece 11, 12, and then the drawing is processed to only process the head connecting hole 112 at the head part 115, and then the connecting piece is flattened, at which time a special mold needs to be designed.

[0068] In summary, the device for detecting the temperature rise of bifurcated connecting pieces in the flow of the present application has three implementation methods. The first implementation method, i.e. the bolt connection scheme of embodiment 1, is convenient and fast to connect, but the test result error caused by the larger contact resistance is slightly increased compared to the other two implementation methods. The second implementation method, i.e. the welding connection scheme of embodiment 2, has a small contact resistance and a small impact on the test result, and does not need to make a connecting hole, but the welding parameter inspection is complex and slow, and additional welding equipment is required. The third implementation method, i.e. the integrated connecting device of embodiment 3, can completely eliminate the contact resistance, but it needs to be arranged in advance to make a machining sample, and cannot directly use the existing connecting piece to punch and connect it into a sample. In actual application scenarios, any one of the above three methods can be selected according to actual needs, and accurate bifurcated connecting piece flow temperature rise data can be obtained.

[0069] Embodiment 4

[0070] The method for detecting the temperature rise of bifurcated connecting pieces in the flow of the present embodiment uses the device of embodiments 1-3, as shown in Figure 9 The detection steps are as follows.

[0071] According to the apparatus of Examples 1-3, test sample 1 is prepared, and then the apparatus is connected. Following the b1 procedure, solder paste is applied to both ends of test sample 1 to facilitate a tighter connection with power connector 2, resulting in a larger contact area and lower contact impedance, thereby reducing the impact of excessive heat generated by contact impedance on the test results.

[0072] (1) Arrange temperature sensing lines

[0073] like Figures 6-8 As shown, two temperature sensing wires are installed in the middle and at one end of the test sample 1. The surface of the temperature sensing wires is secured with Teflon tape. The other end of the temperature sensing wire 4 is connected to the data logger.

[0074] (2) Test sample 1 connection

[0075] Apply solder paste to the head 115 of test sample 1, then connect test sample 1 and power connector 2 using connector 3 (bolt and nut), and then apply torque to the bolt. A torque value of 1~100 NM is recommended. The torque value determination process should also include comparison and verification of contact resistance and heat generation results, and the specific torque value should be determined through verification. Bolt 13 connects the bifurcated connecting pieces 11 and 12 together, and then applies torque to bolt 13. After torque application, test the contact resistance of the bolt 13 connection. The torque value is related to the contact resistance; generally, the larger the torque value, the smaller the contact resistance, and the smaller the error in the test results. When applying torque to bolt 13, ensure the integrity of the connecting pieces during the torque application process to avoid damage to the connecting pieces due to the torque. For welded connecting pieces, pay attention to the flatness and damage of the welded bifurcated connecting pieces 11 and 12.

[0076] (3) Testing and inspection

[0077] Check the set torque value; test the contact internal resistance of sample 1; check the overall connection integrity.

[0078] (4) Initialization and testing

[0079] Place test sample 1 into the environmental chamber, which provides a stable initial ambient temperature. Debug the testing equipment according to procedure c1, and then follow procedure c2 to bring the temperature in the environmental chamber to a stable, predetermined initial temperature, such as 25℃, 45℃, 55℃, or 60℃. Depending on the initial ambient temperature, overcurrent temperature rise tests can be performed on the bifurcated connector at room temperature and high temperature; the specific temperature is set according to the test objective. Set the test steps on the testing equipment according to procedure c3; in the test steps, the test current magnitude, current duration, and settling time are generally set. A cutoff temperature can also be set in the test steps; when the sample surface temperature reaches the cutoff temperature, the testing equipment automatically stops the experiment.

[0080] Figure 10 is an embodiment of a test process setting flow c, when setting a test method according to a process flow, first set the ambient temperature and the sample at the initial set temperature, and then use different X times of current to pass current to the sample, so as to simulate the overcurrent capacity of the bifurcated connecting piece under different times. The recommended times X can be 0.33C, 0.5C, 1C, 2C, 3C, etc. Based on the knowledge of the battery cell, according to the different X times of C current, C is the required capacity of the battery itself of the battery assembled by the connecting piece, the current passing time Y is 3600 / X seconds, and within the test time Y, if the sample 1 temperature exceeds the cut-off temperature, the experiment is stopped immediately. Here, the cut-off temperature is a relatively high value, when the test appears improper connection, improper operation or other accidents, the sample appears temperature rise beyond the reasonable temperature, which may cause wire harness aging, metal melting or fire and other unsafe consequences. Therefore, setting the cut-off temperature is a protective measure for the experiment, and also a prediction of the failure of the test. When the sample 1 temperature exceeds the cut-off temperature, the experiment needs to be stopped immediately. If the sample 1 temperature does not exceed the cut-off temperature, the experiment continues until the test time reaches Y value, after that, the test equipment is powered off, and the current on the sample is turned off; after the sample and the ambient temperature reach the initial value, the temperature rise test of other times is carried out. After the overcurrent temperature rise test of all the required times is completed, the experiment is stopped.

[0081] (5) Post-processing

[0082] After testing according to the test flow c, the temperature data in the data logger 6 is exported first, and then the data is sorted and analyzed to obtain the experimental results according to the data processing flow d. In combination with the previous contact resistance test data, the error of the results is analyzed, and if the results are within the acceptable error range, the test is effective.

[0083] This embodiment simulates the connecting pieces in embodiments 2 and 3, as shown in Figure 14 and 15 , and the specific parameters are as follows.

[0084] (1) Connecting piece parameters: copper material, thickness 0.6 mm, 50*31 mm;

[0085] (2) Simulation purpose: simulate the temperature rise of 95 Ah connecting piece under different current overcurrent;

[0086] (3) Simulation current: 0.33C, 0.5C, 1C, 2C and 3C overcurrent;

[0087] (4) Initial conditions: ambient temperature 25 ℃, heat exchange coefficient 15 W / m 2 K.

[0088] The results are as follows:

[0089] Table 1 Simulation data results (℃)

[0090]

[0091] In this embodiment, the prepared connecting piece is measured, and the parameters are as follows:

[0092] 1. Test conditions: 0.33C, 3h; 0.5C, 2h; 1C, 1h; 2C, 0.5h; 3C, 20min; the test starts from room temperature, and is stopped when the temperature exceeds 120℃.

[0093] 2. Test method: the sample is connected with the current device by bolts, and the corresponding temperature sensing wire is pasted according to the marked serial number. The temperature sensing wire and the connecting piece are wrapped with insulating tape and placed on the insulating pad. The device applies different current rates, and the data instrument records the temperature data.

[0094] The results are as follows:

[0095] Table 2 Measured data results (℃)

[0096]

[0097] From the above data, it can be seen that the connection mode is different, and the internal resistance is different. The internal resistance of the bolt connection is the largest, the internal resistance of the laser welding is the second, and the internal resistance of the integrated connection is the smallest. The smaller the connection resistance is, the smaller the temperature rise is. The greater the current is, the higher the temperature rise is.

[0098] The simulation data and the measured data are summarized, and the results are as follows:

[0099] Table 3 Comparison of test and simulation results (℃)

[0100]

[0101] From the data, it can be seen that the smaller the current is, the smaller the error between the simulation value and the measured value is, and vice versa.

Claims

1. A method for detecting overcurrent temperature rise of a bifurcated connector, comprising a bifurcated connector (11, 12) having a bifurcated portion (114) and a head (115), characterized in that: Two of the bifurcated connecting pieces (11, 12) constitute a test sample (1), the test sample (1) having two heads (115) that are far apart from each other and two bifurcated portions (114) that are close to each other; the bifurcated portions (114) of the two bifurcated connecting pieces (11, 12) overlap or align symmetrically on an axis along the direction of the heads (115) and the bifurcated portions (114); Includes the following steps: S1, wait for the ambient temperature and the test sample (1) to reach the initial temperature; S2, apply a current of multiplier XC to the sample (1) to be tested; S3, if the test sample (1) reaches the cutoff temperature, the test is stopped; if the test sample (1) does not reach the cutoff temperature, the power is continued until the test sample (1) reaches the test time and the test is stopped.

2. The method for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 1, characterized in that: The current of different magnifications XC is passed through the detection sample (1), and the energizing time Y is 3600 / X seconds.

3. The method for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 2, characterized in that: The multiplier XC is 0.33C, 0.5C, 1C, 2C, or 3C.

4. An apparatus for detecting overcurrent temperature rise of a bifurcated connecting piece, implementing the method of any one of claims 1-3, characterized in that: The two forked connecting pieces (11, 12) are connected by bolts (13); the forked part (114) is provided with a tail connecting hole (113) that mates with the bolts (13).

5. The device for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 4, characterized in that: The two bifurcated connecting pieces (11, 12) are welded together by a welding part (14); the welding part (14) is disposed on the surface (111) of the bifurcated connecting pieces (11, 12).

6. The device for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 4, characterized in that: The two forked connecting pieces (11, 12) are welded together by a welding part (14); the welding part (14) is provided at the end of the forked part (114) such that the two forked connecting pieces (11, 12) do not have overlapping projections in the direction perpendicular to the axis.

7. The device for detecting overcurrent temperature rise of a bifurcated connecting piece according to any one of claims 4-6, characterized in that: It also includes a temperature sensing wire connection portion disposed on the surface (111) of the forked connecting piece (11, 12).

8. The device for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 7, characterized in that: There are 6 temperature sensing wire connection parts, which are evenly distributed around the groove formed by the two bifurcated parts (114).

9. The device for detecting overcurrent temperature rise of a bifurcated connecting piece according to claim 8, characterized in that: It also includes detection components, which include a power connector (2), a connection part (3), a temperature sensing wire, a testing device, and a data logger; the power connector (2) and the head (115) are connected through the connection part (3), and the testing device is connected to the power connector (2); the temperature sensing wire is connected to the temperature sensing wire connection part, and the data logger is connected to the temperature sensing wire.

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