Lithium battery DC internal resistance testing device

Abstract

The utility model discloses a lithium battery DC internal resistance testing device, which comprises a data processing module, a battery testing device and a lithium battery, the battery testing device comprises an electronic load, a voltage testing tool and a sampling resistor, the voltage testing tool is respectively connected with the electronic load and the data processing module, and the sampling resistor is connected with the data processing module. The positive electrode of the lithium battery is connected with the positive electrode of a first port in the voltage testing tool and one end of the sampling resistor, the other end of the sampling resistor is connected to the positive electrode of the electronic load, and the negative electrode of the lithium battery is connected with the negative electrode of the first port in the voltage testing tool and the negative electrode of the electronic load. The positive electrode of the second port in the voltage testing tool is connected to one end of the sampling resistor, and the negative electrode of the second port in the voltage testing tool is connected to the other end of the sampling resistor. According to the utility model, the direct-current internal resistance of the lithium battery from any voltage point to the cut-off voltage can be automatically tested.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a device for testing the DC internal resistance of a lithium battery. Background Art

[0002] The internal resistance is one of the important indicators for evaluating the performance of lithium batteries. The internal resistance test includes AC internal resistance (ACR) and DC internal resistance (DCR). The AC internal resistance (ACR), also known as Ohmic internal resistance, is measured by injecting a sinusoidal current signal I = Imax sin(2πft) at the positive and negative electrodes of the battery while measuring the sinusoidal voltage signal U = Umax sin(2πft + ψ) at the positive and negative electrodes of the battery, so as to deduce the AC impedance of the battery. The AC internal resistance usually needs to be measured by an electrochemical workstation to output a Nyquist plot, which is one of the main plots for studying batteries in the field of electrochemistry. The DC internal resistance (DCR) can evaluate the health of the battery, predict the life, and can also estimate the system SOC, output / input capabilities. In production, the DC internal resistance can be used to detect abnormalities in faulty batteries (such as micro-shorts, etc.).

[0003] Due to limitations in terms of the professionalism and cost of testing equipment, for example, electrochemical workstations are often only purchased by scientific research institutions or the battery design and manufacturing industry. Therefore, in real-life applications, it is often impossible or inconvenient to directly test the AC internal resistance of lithium batteries. For example, in small places such as electric vehicle or product repair points, they do not have the ability to purchase electrochemical workstations and do not know how to use them without professional training. Therefore, they can only settle for the next best thing and evaluate the characteristics of the battery through the DC internal resistance. Since the DC internal resistance test devices on the market only test the DC internal resistance of lithium batteries at a single voltage (about 3.6V), it is impossible to comprehensively evaluate the DC internal resistance characteristics of the entire working voltage range of the lithium battery.

[0004] Using the DC internal resistance of a lithium battery at a single voltage (about 3.6V) to evaluate the DC internal resistance characteristics of the battery, this test method has obvious deficiencies. Especially at the end of the lithium battery discharge, the increase in the DC internal resistance will cause the battery voltage to decrease. Because of the differences in lithium battery manufacturing enterprises, manufacturing processes, and raw material formulas, the DC internal resistance values at the end of the lithium battery discharge may vary greatly due to different internal material ratios. However, the differences in the DC internal resistance are not obvious at a voltage of 3.6V. And during the actual use by users, since users cannot charge the lithium battery voltage to the specified test voltage point required by the test instrument, they can only perform the test with the current lithium battery voltage and obtain the test result.

[0005] Such as Figure 1As shown in the figure, in a single 18650 lithium battery (where 18 represents a diameter of 18 mm, 65 represents a length of 65 mm, and 0 represents a cylindrical battery), there is basically no difference in the DC internal resistance characteristics of the two batteries (Sample 1 and Sample 2) before 3.6V. However, in the discharge end range of 3.4V to 3.1V, the DC internal resistance of Sample 1 (dashed line) is significantly greater than that of Sample 2 (solid line). When outputting the same current, Sample 2 can discharge at a lower voltage than Sample 1. If the shutdown voltage set by the terminal device is relatively low (such as 3.3V), when using Sample 1 battery, due to its large internal resistance, during high-current use, because the DC internal resistance is relatively high, the battery voltage drops significantly. Therefore, during user operation, the device may suddenly crash. When using Sample 2 battery, since the voltage drop is small, the terminal can still be used, thus increasing the terminal usage time.

[0006] In order to improve the situation that the existing DC internal resistance test method cannot test the DC internal resistance under the entire voltage range of the lithium battery and cannot compare the DC internal resistance at the discharge end, it is urgent to design a lithium battery DC internal resistance test device that can enumerate and test the DC internal resistance of the lithium battery from any voltage point to the cut-off voltage. Utility Model Content

[0007] In view of this, the purpose of the present utility model is to propose a lithium battery DC internal resistance test device, which can automatically test the DC internal resistance of the lithium battery from any voltage point to the cut-off voltage and form a voltage-internal resistance curve for comparison of multiple battery samples or evaluation of a single sample. It not only evaluates the DC internal resistance characteristics of the lithium battery at a single voltage point, but also evaluates the DC internal resistance of the entire discharge voltage platform, and the obtained data is also more convenient for comparative testing of different samples. Through more comprehensive data output, the selection efficiency is improved during the battery selection stage of product development, preventing the modification of materials in the middle and late stages of the product, resulting in the risk of project delay.

[0008] To achieve the above technical objectives, the technical solution adopted by the present utility model is as follows: A lithium battery DC internal resistance test device includes: a data processing module, a battery test device, and a lithium battery. The battery test device includes an electronic load, a voltage test tooling, and a sampling resistor. The voltage test tooling is respectively connected to the electronic load and the data processing module. The positive electrode of the lithium battery is respectively connected to the positive electrode of the first port in the voltage test tooling and one end of the sampling resistor. The other end of the sampling resistor is connected to the positive electrode of the electronic load. The negative electrode of the lithium battery is respectively connected to the negative electrode of the first port in the voltage test tooling and the negative electrode of the electronic load. The positive electrode of the second port in the voltage test tooling is connected to one end of the sampling resistor, and the negative electrode of the second port in the voltage test tooling is connected to the other end of the sampling resistor.

[0009] Further, the voltage test tooling includes a control unit, an interface conversion unit, a USB interface unit, a first voltage measurement unit, and a second voltage measurement unit. The control unit is respectively connected to an electronic load, the interface conversion unit, the first voltage measurement unit, and the second voltage measurement unit. The USB interface unit is respectively connected to the interface conversion unit and the data processing module. The first voltage measurement unit has a first port, the positive electrode of the first port in the first voltage measurement unit is connected to the positive electrode of the lithium battery, and the negative electrode of the first port in the first voltage measurement unit is connected to the negative electrode of the lithium battery. The second voltage measurement unit has a second port, the positive electrode of the second port in the second voltage measurement unit is connected to one end of the sampling resistor, and the negative electrode of the second port in the second voltage measurement unit is connected to the other end of the sampling resistor.

[0010] Further, the control unit uses an ESP32 chip; the interface conversion unit uses a CH340 chip for serial port and USB interface conversion; the first voltage measurement unit and the second voltage measurement unit use INA228 chips.

[0011] Further, the control unit is connected to the first voltage measurement unit and between the control unit and the second voltage measurement unit through IIC interfaces.

[0012] Further, the control unit is connected to the interface conversion unit through a serial port, and the interface conversion unit is connected to the USB interface unit through a USB interface.

[0013] Further, the USB interface unit communicates with the data processing module through a USB cable.

[0014] Further, the control unit is connected to the electronic load through a serial port, and the control unit controls the opening and closing of the electronic load.

[0015] Further, it further includes a test base. The test base includes a U-shaped fixing seat, a sliding component, a first fixing plate, a second fixing plate, a first conductor, a second conductor, a first probe, and a second probe. The sliding component is slidably installed on the U-shaped fixing seat. The first fixing plate is fixed on the outer side of the left end of the U-shaped fixing seat. The second fixing plate is fixed on the sliding component. The first conductor horizontally penetrates through the upper end of the first fixing plate. The second conductor horizontally penetrates through the upper end of the second fixing plate, and the first conductor and the second conductor are on the same horizontal line.

[0016] The first probe includes a first fixing part and a first telescopic part which are connected to each other. The first fixing part penetrates horizontally inside the first conductor, the first telescopic part is exposed at the inner end of the first conductor, and the first fixing part is exposed at the outer end of the first conductor; the second probe includes a second fixing part and a second telescopic part which are connected to each other. The second fixing part penetrates horizontally inside the second conductor, the second telescopic part is exposed at the inner end of the second conductor, and the second fixing part is exposed at the outer end of the second conductor; the lithium battery is installed between the first conductor and the second conductor, and the positive electrode of the lithium battery is electrically connected to the first telescopic part and the inner side of the first conductor respectively. The first fixing part is connected to the positive electrode of the first port in the voltage test tooling through a first wire, and the outer side of the first conductor is connected to one end of the sampling resistor through a second wire; the negative electrode of the lithium battery is electrically connected to the second telescopic part and the inner side of the second conductor respectively. The second fixing part is connected to the negative electrode of the first port in the voltage test tooling through a third wire, and the outer side of the second conductor is connected to the negative electrode of the electronic load through a fourth wire.

[0017] Further, the sliding assembly includes a lead screw, a slider, a locking handle and an adjusting handwheel. One end of the lead screw passes through the right end of the U-shaped fixing seat and is fixed to the left end of the U-shaped fixing seat. The other end of the lead screw is fixedly connected to the adjusting handwheel. The locking handle is installed on the lead screw and is located outside the right end of the U-shaped fixing seat for locking; the slider is slidably installed on the lead screw and is located in the middle of the U-shaped fixing seat. The second fixing plate is fixed to the slider.

[0018] Further, the data processing module is a host computer.

[0019] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present utility model are as follows:

[0020] 1. In the present utility model, the lithium battery, the voltage test tooling, the electronic load and the sampling resistor are connected in a Kelvin manner, which can minimize the test error when measuring the direct current internal resistance of the lithium battery under large current discharge.

[0021] 2. The present utility model can control the opening and closing of the electronic load through the voltage test tooling, and can realize data acquisition at any voltage point.

[0022] 3. The present utility model calculates the direct current internal resistance at all voltage points from the full charge to the discharge termination of the lithium battery through Ohm's law, and draws a voltage-direct current internal resistance curve graph for convenient analysis.

[0023] 4. Since parameters such as test steps, cut-off voltage points, discharge current, interval time, discharge time, etc. can be configured on the voltage test tooling or the host computer, the present utility model can perform automated testing and generate a voltage - DC internal resistance curve. In order to compare different lithium battery samples, the voltage - DC internal resistance curves of different lithium battery samples can be plotted on the same drawing through the data reading function, assisting in the selection analysis and data comparison in a graphical manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is a graph of the voltage - DC internal resistance of different types of batteries (Sample 1 and Sample 2) in the prior art.

[0026] Figure 2 It is a schematic structural diagram of a lithium battery DC internal resistance test device provided by the present utility model.

[0027] Figure 3 It is a schematic structural diagram of the voltage test tooling provided by the present utility model.

[0028] Figure 4 It is a schematic structural diagram of the test base provided by the present utility model.

[0029] Figure 5 It is a schematic diagram of the working principle provided by the present utility model.

[0030] Explanation of the reference numerals in the drawings:

[0031] 1 - Data processing module, 2 - Battery testing device, 21 - Electronic load, 22 - Voltage testing tooling, 221 - Control unit, 222 - Interface conversion unit, 223 - USB interface unit, 224 - First voltage measurement unit, 225 - Second voltage measurement unit, 226 - First port, 227 - Second port, 23 - Sampling resistor, 3 - Lithium battery, 4 - Testing base, 41 - U-shaped fixing seat, 42 - Sliding assembly, 421 - Lead screw, 422 - Slide block, 423 - Locking handle, 424 - Adjusting handwheel, 43 - First fixing plate, 44 - Second fixing plate, 45 - First conductor, 46 - Second conductor, 47 - First probe, 471 - First fixing part, 472 - First telescopic part, 473 - First wire, 474 - Second wire, 48 - Second probe, 481 - Second fixing part, 482 - Second telescopic part, 483 - Third wire, 484 - Fourth wire. Detailed implementation manner

[0032] The present utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be specifically noted that the following embodiments are only used to illustrate the present utility model, but do not limit the scope of the present utility model. Similarly, the following embodiments are only partial embodiments of the present utility model rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present utility model.

[0033] Please refer to Figures 2 - 5 , a lithium battery DC internal resistance testing device of the present utility model includes: a data processing module 1, a battery testing device 2, and a lithium battery 3. The battery testing device 2 includes an electronic load 21, a voltage testing tooling 22, and a sampling resistor 23. The voltage testing tooling 22 is respectively connected to the electronic load 21 and the data processing module 1. The positive electrode of the lithium battery 3 is respectively connected to the positive electrode of the first port 226 in the voltage testing tooling 22 and one end of the sampling resistor 23. The other end of the sampling resistor 23 is connected to the positive electrode of the electronic load 21. The negative electrode of the lithium battery 3 is respectively connected to the negative electrode of the first port 226 in the voltage testing tooling 22 and the negative electrode of the electronic load 21. The positive electrode of the second port 227 in the voltage testing tooling 22 is connected to one end of the sampling resistor 23. The negative electrode of the second port 227 in the voltage testing tooling 22 is connected to the other end of the sampling resistor 23.

[0034] Due to the Kelvin connection between the lithium battery 3, the voltage test tooling 22, the electronic load 21, and the sampling resistor 23. Among them, there are two Kelvin connections. One is in the detection of the lithium battery 3, where the Kelvin connection is reflected in that two detection lines are led out from the positive electrode of the lithium battery 3, and two detection lines are also led out from the negative electrode. The other is in the current detection, where the Kelvin connection is reflected in that two detection lines are led out from one end of the sampling resistor 23, and two detection lines are also led out from the other end. The connection points of Kelvin must be at specific positions to reduce stray resistance and inductance. By using the Kelvin connection method, the test error can be minimized during the large current discharge of the direct current internal resistance test of the lithium battery 3.

[0035] In this embodiment, the voltage test tooling 22 includes a control unit 221, an interface conversion unit 222, a USB interface unit 223, a first voltage measurement unit 224, and a second voltage measurement unit 225. The control unit 221 is respectively connected to the electronic load 21, the interface conversion unit 222, the first voltage measurement unit 224, and the second voltage measurement unit 225. The USB interface unit 223 is respectively connected to the interface conversion unit 222 and the data processing module 1. The first voltage measurement unit 224 has a first port 226. The positive electrode of the first port 226 in the first voltage measurement unit 224 is connected to the positive electrode of the lithium battery 3, and the negative electrode of the first port 226 in the first voltage measurement unit 224 is connected to the negative electrode of the lithium battery 3. The first voltage measurement unit 224 is connected to an external wiring terminal for measuring the voltage of the lithium battery 3. The second voltage measurement unit 225 has a second port 227. The positive electrode of the second port 227 in the second voltage measurement unit 225 is connected to one end of the sampling resistor 23, and the negative electrode of the second port 227 in the second voltage measurement unit 225 is connected to the other end of the sampling resistor 23. The second voltage measurement unit 225 is used to measure the discharge current of the lithium battery 3. The path formed by the control unit 221, the interface conversion unit 222, and the USB interface unit 223 provides a channel for uploading data to the upper computer. The main working process is as follows: The control unit 221 communicates with the second voltage measurement unit 225 and the first voltage measurement unit 224 through IIC. After obtaining the values of current and voltage, the direct current internal resistance of the lithium battery 3 is calculated. The calculated value is converted into a USB communication method through the interface conversion unit 222 via the serial port and reaches the upper computer after passing through the USB interface unit 223.

[0036] In this embodiment, the control unit 221 uses an ESP32 chip; the interface conversion unit 222 uses a CH340 chip for completing the conversion between the serial port and the USB interface; the first voltage measurement unit 224 and the second voltage measurement unit 225 use INA228 chips.

[0037] In this embodiment, the control unit 221 is connected to the first voltage measurement unit 224 and the control unit 221 is also connected to the second voltage measurement unit 225 through IIC interfaces.

[0038] In this embodiment, the control unit 221 is connected to the interface conversion unit 222 through a serial port, and the interface conversion unit 222 is connected to the USB interface unit 223 through a USB interface.

[0039] In this embodiment, the USB interface unit 223 communicates with the data processing module 1 through a USB cable, which is used to realize data transmission between the voltage test tooling 22 and the data processing module 1.

[0040] In this embodiment, the control unit 221 is connected to the electronic load 21 through a serial port, and the control unit 221 controls the turning on and off of the electronic load 21. Serial communication is used with a baud rate of 9600. The voltage test tooling 22 controls the turning on and off of the electronic load 21 by sending serial commands (such as: ON / OFF).

[0041] In this embodiment, a test base 4 is further included. The test base 4 includes a U-shaped fixing seat 41, a sliding component 42, a first fixing plate 43, a second fixing plate 44, a first conductor 45, a second conductor 46, a first probe 47, and a second probe 48. The sliding component 42 is slidably mounted on the U-shaped fixing seat 41. The first fixing plate 43 is fixed to the outer side of the left end of the U-shaped fixing seat 41, and the second fixing plate 44 is fixed to the sliding component 42. The first conductor 45 horizontally penetrates through the upper end of the first fixing plate 43, and the second conductor 46 horizontally penetrates through the upper end of the second fixing plate 44, and the first conductor 45 and the second conductor 46 are on the same horizontal line.

[0042] The first probe 47 includes a first fixing part 471 and a first telescopic part 472 which are connected to each other. The first telescopic part 472 is a telescopic structure. The first fixing part 471 penetrates transversely inside the first conductor 45. The first telescopic part 472 is exposed at the inner end of the first conductor 45, and the first fixing part 471 is exposed at the outer end of the first conductor 45. The second probe 48 includes a second fixing part 481 and a second telescopic part 482 which are connected to each other. The second telescopic part 482 is a telescopic structure. The second fixing part 481 penetrates transversely inside the second conductor 46. The second telescopic part 482 is exposed at the inner end of the second conductor 46, and the second fixing part 481 is exposed at the outer end of the second conductor 46. The lithium battery 3 is installed between the first conductor 45 and the second conductor 46. At this time, the first telescopic part 472 and the second telescopic part 482 are compressed outwards and contact the electrodes of the lithium battery 3. And the positive electrode of the lithium battery 3 is electrically connected to the inner sides of the first telescopic part 472 and the first conductor 45 respectively. The first fixing part 471 is connected to the positive electrode of the first port 226 in the voltage test tooling 22 through a first wire 473. The outer side of the first conductor 45 is connected to one end of a sampling resistor 23 through a second wire 474. The negative electrode of the lithium battery 3 is electrically connected to the inner sides of the second telescopic part 482 and the second conductor 46 respectively. The second fixing part 481 is connected to the negative electrode of the first port 226 in the voltage test tooling 22 through a third wire 483. The outer side of the second conductor 46 is connected to the negative electrode of the electronic load 21 through a fourth wire 484. The structure of the test base 4 can provide a stable test environment for the test of the lithium battery 3.

[0043] In this embodiment, the sliding assembly 42 includes a lead screw 421, a slider 422, a locking handle 423 and an adjusting handwheel 424. One end of the lead screw 421 passes through the right end of the U-shaped fixing seat 41 and is fixed to the left end of the U-shaped fixing seat 41. The other end of the lead screw 421 is fixedly connected to the adjusting handwheel 424. The locking handle 423 is installed on the lead screw 421 and is located outside the right end of the U-shaped fixing seat 41 for locking. The slider 422 is slidably installed on the lead screw 421 and is located in the middle of the U-shaped fixing seat 41. The second fixing plate 44 is fixed to the slider 422. The distance between the first conductor 45 and the second conductor 46 is adjusted by sliding the slider 422 on the lead screw 421, so as to facilitate the test of lithium batteries 3 of different sizes and types.

[0044] In this embodiment, the data processing module 1 is a host computer. By using the host computer, operation steps can be set, such as configuring the cut-off voltage point, discharge current, interval time, discharge time, etc. The test parameters can also be read and the test data can be analyzed.

[0045] The working principle of the present utility model is as follows:

[0046] First, the host computer performs initialization settings to configure the discharge current, battery rest time, cut-off voltage, discharge time, etc. Then, the voltage of the lithium battery 3 is read through the first voltage measurement unit 224 of the voltage test fixture 22. If it is greater than the cut-off voltage, the test starts, otherwise it ends. When the test starts, the lithium battery 3 is first silenced, and then the voltage V0 of the lithium battery 3 when it is static (no load) is read. Next, turn on the voltage test fixture 22 and send a command: ON to the electronic load 21, which is turned on after receiving it. When the current flows through the sampling resistor 23, a voltage drop is generated at both ends of the sampling resistor 23. At this time, the voltage of the sampling resistor 23 is read through the second voltage measurement unit 225 of the voltage test fixture 22. According to Ohm's law, the voltage at both ends of the sampling resistor 23 and the resistance value of the sampling resistor 23, the actual discharge current I is calculated, and compared with the preset discharge current on the electronic load 21. When the difference is within the threshold range, the subsequent calculation is based on the actual discharge current I, which can improve the accuracy of the current measurement. When the discharge time is reached, the voltage test fixture 22 sends a command: OFF to the electronic load 21, and the electronic load 21 is turned off after receiving it. Before turning off, the voltage V1 at both ends of the lithium battery 3 is read by the first voltage measurement unit 224 of the voltage test fixture 22. The DC internal resistance of the lithium battery 3 is calculated by Ohm's law: (V0-V1) / I. Since the opening and closing of the electronic load 21 can be controlled by the voltage test fixture 22 until the discharge current of the electronic load 21 is released; in this way, the voltage V1 and DC internal resistance data corresponding to the lithium battery 3 from any voltage point to the cut-off voltage can be calculated according to actual needs, and a voltage-DC internal resistance curve can be drawn through multiple sets of different data. Since the test steps, cut-off voltage points, discharge currents, intervals, discharge times and other parameters can be configured on the voltage test fixture 22 or the host computer, the voltage-DC internal resistance curve can be automatically tested and generated. Finally, in order to compare different samples, the voltage-DC internal resistance curves of different lithium battery 3 samples can be drawn on the same drawing through the data reading function, and the selection analysis and data comparison can be assisted in a graphical manner.

[0047] The above descriptions are only some embodiments of the present invention, and do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A lithium battery DC internal resistance test device, characterized in that: include: A data processing module, a battery testing device and a lithium battery, wherein the battery testing device comprises an electronic load, a voltage testing tool and a sampling resistor, wherein the voltage testing tool is respectively connected to the electronic load and the data processing module, the positive electrode of the lithium battery is respectively connected to the positive electrode of the first port in the voltage testing tool and one end of the sampling resistor, the other end of the sampling resistor is connected to the positive electrode of the electronic load, the negative electrode of the lithium battery is respectively connected to the negative electrode of the first port in the voltage testing tool and the negative electrode of the electronic load, the positive electrode of the second port in the voltage testing tool is connected to one end of the sampling resistor, and the negative electrode of the second port in the voltage testing tool is connected to the other end of the sampling resistor.

2. A lithium battery DC internal resistance test device as claimed in claim 1, characterized in that: The voltage testing tool includes a control unit, an interface conversion unit, a USB interface unit, a first voltage measuring unit and a second voltage measuring unit. The control unit is respectively connected to the electronic load, the interface conversion unit, the first voltage measuring unit and the second voltage measuring unit, and the USB interface unit is respectively connected to the interface conversion unit and the data processing module; the first voltage measuring unit has a first port, the positive pole of the first port in the first voltage measuring unit is connected to the positive pole of the lithium battery, and the negative pole of the first port in the first voltage measuring unit is connected to the negative pole of the lithium battery; the second voltage measuring unit has a second port, the positive pole of the second port in the second voltage measuring unit is connected to one end of the sampling resistor, and the negative pole of the second port in the second voltage measuring unit is connected to the other end of the sampling resistor.

3. A lithium battery DC internal resistance test device as claimed in claim 2, characterized in that: The control unit adopts ESP32 chip; the interface conversion unit adopts CH340 chip, which is used to complete the conversion between the serial port and the USB interface; the first voltage measurement unit and the second voltage measurement unit adopt INA228 chip.

4. A lithium battery DC internal resistance test device as claimed in claim 2, characterized in that: The control unit and the first voltage measuring unit, as well as the control unit and the second voltage measuring unit are connected via an IIC interface.

5. A lithium battery DC internal resistance test device as claimed in claim 2, characterized in that: The control unit is connected to the interface conversion unit via a serial port, and the interface conversion unit is connected to the USB interface unit via a USB interface.

6. A lithium battery DC internal resistance test device as claimed in claim 2, characterized in that: The USB interface unit communicates with the data processing module via a USB line.

7. A lithium battery DC internal resistance test device as claimed in claim 2, characterized in that: The control unit is connected to the electronic load via a serial port, and the control unit controls the electronic load to be turned on and off.

8. A lithium battery DC internal resistance test device as claimed in claim 1, characterized in that: The test base also includes a test base, which includes a U-shaped fixed base, a sliding assembly, a first fixed plate, a second fixed plate, a first conductor, a second conductor, a first probe and a second probe. The sliding assembly can be slidably mounted on the U-shaped fixed base, the first fixed plate is fixed to the outer side of the left end of the U-shaped fixed base, and the second fixed plate is fixed to the sliding assembly; the first conductor is horizontally inserted through the upper end of the first fixed plate, the second conductor is horizontally inserted through the upper end of the second fixed plate, and the first conductor and the second conductor are located on the same horizontal line; The first probe comprises a first fixed portion and a first telescopic portion connected to each other, the first fixed portion laterally penetrates the interior of the first conductor, the first telescopic portion is exposed at the inner end of the first conductor, and the first fixed portion is exposed at the outer end of the first conductor; the second probe comprises a second fixed portion and a second telescopic portion connected to each other, the second fixed portion laterally penetrates the interior of the second conductor, the second telescopic portion is exposed at the inner end of the second conductor, and the second fixed portion is exposed at the outer end of the second conductor; the lithium battery is installed between the first conductor and the second conductor, and the positive electrode of the lithium battery is electrically connected to the first telescopic portion and the inner side of the first conductor respectively, the first fixed portion is connected to the positive electrode of the first port in the voltage test fixture through a first wire, and the outer side of the first conductor is connected to one end of the sampling resistor through a second wire; the negative electrode of the lithium battery is electrically connected to the second telescopic portion and the inner side of the second conductor respectively, the second fixed portion is connected to the negative electrode of the first port in the voltage test fixture through a third wire, and the outer side of the second conductor is connected to the negative electrode of the electronic load through a fourth wire.

9. A lithium battery DC internal resistance test device as claimed in claim 8, characterized in that: The sliding assembly includes a screw rod, a slider, a locking handle and an adjusting handwheel. One end of the screw rod passes through the right end of the U-shaped fixing seat and is fixed to the left end of the U-shaped fixing seat. The other end of the screw rod is fixedly connected to the adjusting handwheel. The locking handle is installed on the screw rod and is located on the outer side of the right end of the U-shaped fixing seat for locking. The slider is slidably installed on the screw rod and is located in the middle of the U-shaped fixing seat. The second fixing plate is fixed on the slider.

10. A lithium battery DC internal resistance test device as claimed in claim 1, characterized in that: The data processing module is a host computer.

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