Battery electrolyte leakage and surface temperature test device and test method thereof

Abstract

The invention relates to the technical field of battery testing, in particular to a battery electrolyte leakage and surface temperature testing device and a testing method thereof.The battery electrolyte leakage and surface temperature testing device comprises an upper computer, a data acquisition control unit, a temperature control unit, a thermal imaging unit, a smoke sensing unit, an electrolyte leakage acquisition unit, a fire extinguishing spraying unit and an alarm unit. According to the invention, a brand new design idea and method are adopted, brand new data acquisition, temperature control, data processing and the like are adopted, and the problems of complex test operation, low efficiency, low measurement precision, low safety performance and the like are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery testing, and particularly relates to a battery electrolyte leakage and surface temperature test device and a test method based on the test device. Background Art

[0002] The battery electrolyte leakage test and the surface temperature test are important test items in GB / T 3836.4-2021 "Explosive atmospheres - Part 4: Equipment protected by type 'i' of intrinsic safety". For batteries and battery packs used in intrinsically safe equipment, at least 10 batteries or battery packs need to be measured simultaneously at different temperatures, and the resistance of the measurement circuit should not be greater than 3 mΩ. It is necessary to monitor the voltage, current, temperature, etc. of the battery, as well as whether there is electrolyte leakage.

[0003] The existing battery electrolyte leakage test and surface temperature test are completed by using independent conventional test equipment, including a multimeter, an ammeter, and a thermocouple recorder. The operation is relatively cumbersome, time-consuming and laborious, with low efficiency, large measurement errors, and there are no protective measures during the test, posing potential safety hazards. Summary of the Invention

[0004] The purpose of the present invention is to provide a battery electrolyte leakage and surface temperature test device and a test method based on the test device, which adopt a brand-new design concept and method, and use brand-new data acquisition, temperature control, data processing, etc., to solve the problems of complex test operation, low efficiency, low measurement accuracy, and low safety performance.

[0005] Based on the above technical problems, the present invention provides a battery electrolyte leakage and surface temperature test device, including a host computer, a data acquisition and control unit, a temperature control unit, a thermal imaging unit, a smoke sensing unit, an electrolyte leakage acquisition unit, a fire extinguishing spray unit, and an alarm unit;

[0006] The data acquisition and control unit is respectively connected to the host computer and the battery, and is used for collecting parameters related to the voltage, current, and temperature of the battery, and uploading the parameters to the host computer;

[0007] The temperature control unit is respectively connected to the host computer and the data acquisition and control unit, and is used for controlling the ambient temperature of the battery to be tested;

[0008] The thermal imaging unit and the smoke sensing unit are respectively connected to the host computer and the data acquisition and control unit. The thermal imaging unit monitors the temperature image of the short circuit of the battery to be tested in real time, and transmits the relevant temperature data to the host computer. The smoke sensing unit monitors the smoke state of the test environment in real time, and sends the state to the host computer;

[0009] The electrolyte leakage collection unit is respectively connected to the host computer and the data acquisition control unit, and is used to collect the electrolyte generated by the battery and send the video image to the host computer;

[0010] The fire extinguishing spray unit and the alarm unit are respectively connected to the host computer and the data acquisition control unit, and are used to perform the fire extinguishing spray action and send out an alarm signal.

[0011] To ensure the safety and effectiveness of the test, the data acquisition control unit includes a test chamber and a control switch, a non-contact DC voltage transformer, and a non-contact current transformer arranged in the test chamber. The control switch, the non-contact DC voltage transformer, and the non-contact current transformer are connected to the battery to form a test circuit.

[0012] To ensure the acquisition accuracy, thermocouples are respectively arranged at the front end, middle end, and rear end of the battery.

[0013] To ensure the efficiency of data acquisition, the data acquisition control unit uses an STM32 high-speed acquisition processor and a high-precision AD conversion chip to achieve high-frequency acquisition of current, voltage, and temperature.

[0014] To achieve precise control of the test environment temperature, the temperature control unit includes a double-group high-power compressor, a double-group heater, and a circulation fan arranged in the test chamber to control the environment temperature of the test chamber.

[0015] To ensure the accuracy and effectiveness of the electrolyte leakage test, a polymer absorbent paper is placed under the battery, and the electrolyte leakage collection unit uses a high-definition camera to collect the electrolyte traces on the polymer absorbent paper and sends the video image to the host computer.

[0016] The present invention also provides a test method for the above-mentioned battery electrolyte leakage and surface temperature test device, including the following steps:

[0017] (1) Connect the entire test device to an AC power supply, and each unit is powered on;

[0018] (2) Install multiple groups of batteries to be tested into the test chamber of the data acquisition control unit, and place polymer absorbent paper under each group of batteries;

[0019] (3) Turn on the host computer, set the required test conditions through the host computer, and start the test;

[0020] (4) The host computer sends a command to the data acquisition control unit, and the data acquisition control unit starts the temperature control unit. The ambient temperature inside the test chamber is gradually heated from room temperature to 40°C. When the data acquisition control unit detects that the ambient temperature inside the test chamber reaches 40°C, the data acquisition control unit controls the control switch of the battery test circuit to close, and starts the surface temperature short-circuit test of the battery. The resistance of the short-circuit test circuit is not greater than 3 mΩ;

[0021] (5) During the test, the data acquisition control unit collects the voltage, current, and temperature-related parameters of the battery, and transmits them to the host computer wirelessly through LoRa. The electrolyte leakage acquisition unit collects the video images of the battery and the polymer absorbent paper and uploads them to the host computer. The thermal imaging unit collects the temperature image of the battery and uploads it to the host computer;

[0022] (6) If the battery temperature does not exceed the test conditions and there is no fire or explosion, when the battery temperature approaches the ambient temperature, the surface temperature short-circuit test ends; if the surface temperature open-circuit test passes, then the battery electrolyte leakage test is carried out. At least 12 hours after the surface temperature open-circuit test ends, it is judged by the host computer that there is no obvious electrolyte leakage on the battery surface and the polymer absorbent paper, and the battery electrolyte leakage test passes. Otherwise, the battery electrolyte leakage test fails;

[0023] If the battery temperature collected by the thermal imaging unit exceeds the test conditions and the smoke sensing unit collects the smoke signal of the battery catching fire, the host computer sends a signal to the data acquisition control unit. The data acquisition control unit opens the control switch of the battery test circuit. At the same time, the data acquisition control unit opens the switch of the fire extinguishing spray unit, the fire extinguishing spray action is carried out, and the alarm is turned on at the same time to generate an alarm signal, and the test ends.

[0024] To ensure the test accuracy, preferably, the voltage acquisition software part of the data acquisition control unit adopts the median filtering method, continuously samples the voltage parameters of the battery to be tested 101 times, arranges the 101 values in descending order, and takes the middle value as the voltage value of this sampling;

[0025] The current acquisition software part of the data acquisition control unit adopts the sliding average filtering method, continuously collects 50 data. The 50 data form a queue, that is, the length of the queue is 50. Each time a new current data is collected and placed at the end of the queue, and the data at the head of the queue is removed. According to the principle of first in first out, the 50 data in the queue are arithmetically averaged to obtain the required filtering result;

[0026] The temperature acquisition software of the data acquisition control unit adopts the adaptive weighted recursive average filtering method. Based on the recursive idea, different weights are assigned to the current sampling value and the filtering value at the previous moment to achieve the smoothing processing of the temperature signal. The formula is as follows:

[0027] Y(n) = α × X(n) + (1 - α) × Y(n - 1) where:

[0028] Y(n) is the filtered output value at the current moment,

[0029] X(n) is the sampled value at the current moment,

[0030] Y(n - 1) is the filtered output value at the previous moment,

[0031] α is the weight coefficient.

[0032] Furthermore, the host computer software adjusts the sampling time intervals of the current signal, voltage signal, and temperature according to the change rate of the sampled current value. At the initial stage of the short circuit, the sampling interval time is 0.5 s. In the middle stage, as the change rate of the current data becomes smaller, the sampling interval time is 1 s. In the later stage, as the change rate of the current data continues to become smaller, the sampling interval time is 2 s.

[0033] To ensure the test accuracy, preferably, the temperature control unit uses an improved PID algorithm for control. By combining proportional, integral, and derivative controls, it achieves fast response, reduces overshoot, and eliminates steady-state error. The formula is as follows:

[0034] Δt(n) = Kp × [e(n) - e(n - 1)] + Ki × e(n) + Kd × [e(n) - 2e(n - 1) + e(n - 2)]

[0035] where:

[0036] Δt(n) is the increment of the temperature at the nth time,

[0037] e(n) is the error at the nth time, that is, e(n) = set value - actual temperature value,

[0038] Kp is the proportional gain, taking 0.2,

[0039] Ki is the integral gain, taking 0.13,

[0040] Kd is the derivative gain, taking 0.3,

[0041] The actual control temperature t(n) is calculated through the increment Δt(n), and the previous temperature is t(n - 1). The formula is as follows:

[0042] t(n) = t(n - 1) + Δt(n).

[0043] The beneficial effects of the present invention are as follows: The present invention adopts a brand-new design concept. In terms of collecting battery voltage and current parameters, non-contact collection is used, which avoids measurement errors caused by poor contact, effectively resists external electromagnetic interference, and ensures the accuracy and stability of measurement; in terms of temperature collection, the method of arranging thermocouples at multiple points and an improved software collection algorithm are adopted to ensure the highest value of the battery surface temperature collected; a wireless communication technology is used between the data acquisition control unit and the upper computer, solving the trouble of wiring; the thermal imaging and temperature collection unit ensures safety during the test process and avoids the occurrence of danger; the temperature control unit adopts an advanced algorithm and can quickly and accurately adjust the internal environmental temperature of the device; the electrolyte leakage collection unit adopts video collection and image recognition methods, avoiding manual discrimination and judgment, improving work efficiency, and reducing the probability of misjudgment; it can simultaneously test 10 groups of batteries, improving work efficiency; advanced test equipment and software algorithms are adopted to improve the measurement accuracy and quality; environmental temperature control is added, avoiding the need for testing only at a single environmental temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of the battery electrolyte leakage and surface temperature test device of the present invention;

[0045] Figure 2 is a schematic structural diagram of the data acquisition control unit of the present invention;

[0046] Figure 3 is a layout diagram of the battery and the high molecular water-absorbing paper in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The following elaborates on the preferred embodiments of the present invention in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0048] As Figure 1 shown, a battery electrolyte leakage and surface temperature test device includes an upper computer, a data acquisition control unit, a temperature control unit, a thermal imaging unit, a smoke sensing unit, an electrolyte leakage collection unit, a fire extinguishing spray unit, and an alarm unit. The data acquisition control unit is respectively connected to the upper computer and the battery, and the temperature control unit, the thermal imaging unit, the smoke sensing unit, the electrolyte leakage collection unit, the fire extinguishing spray unit, and the alarm unit are respectively connected to the upper computer and the data acquisition control unit.

[0049] Specifically, in combination with Figure 2As shown in the figure, the data acquisition control unit includes a test chamber and a control switch K, a non-contact DC voltage transformer U, and a non-contact current transformer I arranged inside the test chamber. The control switch K, the non-contact DC voltage transformer U, and the non-contact current transformer I are connected to a battery B to form a test circuit, where B is a cylindrical lithium battery, and thermocouples are arranged at the front end, middle part, and rear end of the battery respectively.

[0050] For the acquisition of the open-circuit voltage of the battery and the voltage and current signals during the short-circuit process, the present invention uses a non-contact DC voltage transformer, which will not affect the electrical parameters of the battery measurement circuit, does not change the inherent characteristics of the original circuit, does not require complex circuit wiring, avoids electrical accidents caused by direct contact, avoids measurement errors caused by poor contact, and can effectively resist external electromagnetic interference, ensuring the accuracy and stability of the measurement; the measurement of the short-circuit current of the battery also uses non-contact measurement.

[0051] The present invention uses a miniaturized design for the thermocouples, carefully designs the installation method, arranges the thermocouples at multiple points, arranges the thermocouples at the front end, middle part, and rear end of the battery respectively, and uses a specific fixing glue to fix the thermocouples evenly and firmly, ensuring that the thermocouples can work stably throughout the battery short-circuit process and are not affected by battery deformation.

[0052] The data acquisition control unit uses an STM32 high-speed acquisition processor and a high-precision AD conversion chip to achieve high-frequency acquisition of current, voltage, and temperature;

[0053] Among them, for the voltage acquisition software part, the median filtering method is used. The voltage parameter is continuously sampled 101 times, and the 101 values are arranged in descending order, and the middle value is taken as the voltage value of this sampling;

[0054] For the current acquisition software part, the moving average filtering method is used. 50 data are continuously acquired. The 50 data form a queue, that is, the length of the queue is 50. Each time a new current data is acquired, it is placed at the end of the queue, and the data at the head of the queue is removed. According to the principle of first in first out, the 50 data in the queue are arithmetically averaged to obtain the required filtering result;

[0055] For the temperature acquisition software, the adaptive weighted recursive average filtering method is used. Based on the recursive idea, different weights are assigned to the current sampling value and the filtering value at the previous moment to achieve the smoothing processing of the temperature signal. The formula is as follows:

[0056] Y(n) = α×X(n) + (1 - α)×Y(n - 1) where:

[0057] Y(n) is the filtering output value at the current moment,

[0058] X(n) is the sampling value at the current moment,

[0059] Y(n - 1) is the filtered output value at the previous moment,

[0060] α is the weight coefficient.

[0061] In the initial stage of the short circuit, the weight coefficient of the current temperature sampling value is 0.3. As the temperature change rate slows down, the weight coefficient of the temperature sampling value in the middle and later stages is 0.1.

[0062] In addition, the host computer software adjusts the sampling time intervals of the current signal, voltage signal, and temperature according to the change rate of the sampled current value. In the initial stage of the short circuit, the sampling interval time is 0.5 s. In the middle stage, as the change rate of the current data becomes smaller, the sampling interval time is 1 s. In the later stage, as the change rate of the current data continues to become smaller, the sampling interval time is 2 s.

[0063] The thermal imaging unit monitors the temperature image of the battery short circuit in real time and transmits the relevant temperature data to the host computer. The smoke sensing unit monitors the smoke state inside the entire battery test cabinet in real time and sends the status to the host computer. The host computer comprehensively judges the battery state through the thermal imaging data, smoke data, and battery data. When the temperature exceeds the corresponding temperature groups (T1: 450 °C, T2: 300 °C, T3: 200 °C, T4: 135 °C, T5: 100 °C, T6: 85 °C), when a fire or explosion occurs, the data acquisition control unit is controlled to disconnect the battery circuit. At the same time, an alarm signal is issued to start the spray fire extinguishing unit to avoid further expansion of the danger.

[0064] The temperature control unit is mainly used to control the ambient temperature inside the battery test chamber. The test chamber is equipped with two groups of high-power compressors and two groups of heaters, and it can cool down to 40 °C and heat up to 40 °C in less than 30 minutes. At the same time, the test chamber is equipped with a circulating fan to keep the ambient temperature uniform. The temperature control software part uses an improved PID algorithm for control. Through the combination of proportional, integral, and differential controls, it realizes fast response, reduces overshoot, and eliminates steady-state error. The formula is as follows:

[0065] Δt(n) = Kp × [e(n) - e(n - 1)] + Ki × e(n) + Kd × [e(n) - 2e(n - 1) + e(n - 2)]

[0066] Where:

[0067] Δt(n) is the increment of the temperature at the nth time,

[0068] e(n) is the error at the nth time, that is, e(n) = set value - actual temperature value,

[0069] Kp is the proportional gain, taking 0.2,

[0070] Ki is the integral gain, taking 0.13,

[0071] Kd is the differential gain, which is taken as 0.3.

[0072] The actual control temperature t(n) is calculated through the increment Δt(n). The previous temperature is t(n - 1). The formula is as follows:

[0073] t(n) = t(n - 1) + Δt(n).

[0074] For the electrolyte leakage collection unit, a polymer absorbent paper P is placed under the battery. As Figure 3 shown, after the surface temperature test is completed, after 12 hours, if the battery has electrolyte leakage, there will be electrolyte traces on the battery surface or the polymer absorbent paper P. A high-definition camera is used to send the video image to the upper computer, and the upper computer uses image recognition technology to determine whether there is electrolyte leakage.

[0075] The fire extinguishing spray unit controls the fire extinguishing spray action through the controller, and the alarm unit issues an alarm signal.

[0076] The test method of this battery electrolyte leakage and surface temperature test device includes the following steps:

[0077] The entire test device is powered by AC220V AC power supply. The camera of the electrolyte leakage collection unit starts to get power and work. The double-group high-power compressors, double-group heaters, and circulation fans for controlling the internal environment temperature of the test chamber start to get power. The over-temperature (battery fire) alarm of the alarm unit gets power. The fire extinguishing controller of the fire extinguishing spray unit gets power. The smoke sensor of the smoke sensing unit gets power. The thermal imager of the thermal imaging unit gets power. The data acquisition controller of the data acquisition control unit gets power and works;

[0078] Ten cylindrical batteries are installed in the test chamber of the data acquisition control unit, and polymer absorbent paper is placed under each group of batteries;

[0079] The upper computer and the display are powered on. The upper computer software is opened, and then the required test conditions are set through the upper computer. For example, the test environment temperature is set to 40°C, and the allowable temperature on the battery surface is set to T3 (200°C). Then, click Start Test;

[0080] The upper computer sends a command to the data acquisition controller. The data acquisition controller starts the double-group high-power compressors, double-group heaters, and circulation fans. The internal environment temperature of the test chamber is gradually heated from room temperature to 40°C. When the data acquisition controller detects that the internal environment temperature of the test chamber reaches 40°C, the data acquisition controller controls the control switch of the battery test circuit to close, and starts the short-circuit test of the battery surface temperature. The resistance of the short-circuit test circuit is not greater than 3 mΩ;

[0081] During the test, the data acquisition controller collects parameters such as the voltage, current, and temperature of the battery, and transmits them wirelessly to the host computer via LoRa. The camera collects the drawings of the battery and the superabsorbent polymer paper and sends them to the host computer. The thermal imager collects the battery temperature and uploads it to the host computer. During the test, if the battery temperature does not exceed T3 (200 °C), and there is no fire or explosion, when the battery temperature approaches the ambient temperature, the surface temperature short-circuit test ends;

[0082] During the test, if the host computer software collects that the battery temperature sent by the data acquisition controller exceeds T3 (200 °C), the battery temperature collected by the thermal imager exceeds T3 (200 °C), or the smoke sensor collects the smoke signal of the battery catching fire, the host computer sends a signal to the data acquisition controller. The data acquisition controller turns on the switch of the battery test circuit. At the same time, the data acquisition controller turns on the switch of the fire extinguishing controller, and the fire extinguishing spray operates. In addition, the data acquisition controller turns on the alarm to generate an alarm signal, and the test ends;

[0083] If the surface temperature test passes, the battery electrolyte leakage test is carried out. At least 12 hours after the surface temperature test ends, it is judged by the host computer software that there is no obvious electrolyte leakage on the battery surface and the superabsorbent polymer paper. The battery electrolyte leakage test passes; otherwise, the battery electrolyte leakage test fails.

[0084] Finally, it should be noted that the above embodiments are only specific implementation manners of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A battery electrolyte leakage and surface temperature test device, characterized in that: It includes a host computer, a data acquisition control unit, a temperature control unit, a thermal imaging unit, a smoke sensor unit, an electrolyte leakage acquisition unit, a fire extinguishing spray unit and an alarm unit; The data acquisition control unit is connected to the host computer and the battery respectively, and is used to collect the voltage, current and temperature related parameters of the battery, and upload the parameters to the host computer; The temperature control unit is connected to the host computer and the data acquisition control unit respectively, and is used to control the ambient temperature of the battery to be tested; The thermal imaging unit and the smoke sensing unit are connected to the host computer and the data acquisition control unit respectively. The thermal imaging unit monitors the temperature image of the short circuit of the battery to be tested in real time and transmits the relevant temperature data to the host computer. The smoke sensing unit monitors the smoke state of the test environment in real time and sends the state to the host computer. The electrolyte leakage collection unit is connected to the host computer and the data acquisition control unit respectively, and is used to collect the electrolyte generated by the battery and send the video image to the host computer; The fire extinguishing spray unit and the alarm unit are respectively connected to the host computer and the data acquisition control unit, and are used to perform fire extinguishing spray actions and send out alarm signals.

2. The battery electrolyte leakage and surface temperature testing device according to claim 1, characterized in that: The data acquisition control unit includes a test box and a control switch, a non-contact DC voltage transformer, and a non-contact current transformer arranged in the test box. The control switch, the non-contact DC voltage transformer, and the non-contact current transformer are connected to a battery to form a test loop.

3. The battery electrolyte leakage and surface temperature testing device according to claim 2, characterized in that: Thermocouples are arranged at the front end, middle part and rear end of the battery respectively.

4. The battery electrolyte leakage and surface temperature testing device according to claim 3, characterized in that: The data acquisition control unit adopts an STM32 high-speed acquisition processor and a high-precision AD conversion chip to achieve high-frequency acquisition of current, voltage, and temperature.

5. The battery electrolyte leakage and surface temperature testing device according to claim 3, characterized in that: The temperature control unit includes two groups of high-power compressors, two groups of heaters and circulating fans arranged in the test box to control the ambient temperature of the test box.

6. The battery electrolyte leakage and surface temperature testing device according to claim 3, characterized in that: A polymer absorbent paper is placed under the battery, and an electrolyte leakage collection unit uses a high-definition camera to collect electrolyte traces on the polymer absorbent paper and sends video images to a host computer.

7. A method for testing the battery electrolyte leakage and surface temperature test device according to any one of claims 1 to 6, characterized in that: The steps include: (1) The entire test device is connected to an AC power source and each unit is powered; (2) Install multiple groups of batteries to be tested into the test box of the data acquisition control unit, and place polymer absorbent paper under each group of batteries; (3) Turn on the host computer, set the required test conditions through the host computer, and start the test; (4) The host computer sends a command to the data acquisition control unit, which starts the temperature control unit. The ambient temperature inside the test chamber is gradually heated from room temperature to 40°C. When the data acquisition control unit detects that the ambient temperature inside the test chamber reaches 40°C, the data acquisition control unit controls the control switch of the battery test circuit to close and starts the battery surface temperature short-circuit test. The resistance of the short-circuit test circuit is no more than 3mΩ. (5) During the test, the data acquisition control unit collects the voltage, current, and temperature-related parameters of the battery and transmits them to the host computer via LoRa wireless. The electrolyte leakage acquisition unit collects video images of the battery and polymer absorbent paper and uploads them to the host computer. The thermal imaging unit collects temperature images of the battery and uploads them to the host computer. (6) If the battery temperature does not exceed the test conditions and there is no fire or explosion, the surface temperature short-circuit test ends when the battery temperature approaches the ambient temperature; If the surface temperature short circuit test is passed, the battery electrolyte leakage test is carried out. At least 12 hours after the surface temperature short circuit test is completed, the host computer judges that there is no obvious electrolyte leakage on the battery surface and the polymer absorbent paper. The battery electrolyte leakage test is passed. Otherwise, the battery electrolyte leakage test is failed. If the battery temperature collected by the thermal imaging unit exceeds the test conditions and the smoke sensor unit collects the smoke signal of battery fire, the host computer sends a signal to the data acquisition control unit, and the data acquisition control unit turns on the control switch of the battery test circuit. At the same time, the data acquisition control unit turns on the switch of the fire extinguishing spray unit, the fire extinguishing spray is activated, and the alarm is turned on at the same time, generating an alarm signal, and the test ends.

8. The test method of the battery electrolyte leakage and surface temperature test device according to claim 7, characterized in that: The voltage acquisition software of the data acquisition control unit adopts the median value filtering method to continuously sample the voltage parameters of the battery to be tested 101 times, arrange the 101 values ​​in order from large to small, and take the middle value as the voltage value of this sampling; The current acquisition software of the data acquisition control unit adopts the sliding average filtering method to continuously collect 50 data. The 50 data are used as a queue, that is, the length of the queue is 50. Each time a new current data is collected, it is placed at the end of the queue, and the data at the head of the queue is removed. According to the first-in-first-out principle, the 50 data in the queue are calculated by arithmetic average to obtain the required filtering result. The temperature acquisition software of the data acquisition control unit adopts the adaptive weighted recursive average filtering method. Based on the recursive idea, different weights are assigned to the current sampling value and the filtering value at the previous moment to achieve smooth processing of the temperature signal. The formula is as follows: Y(n)=α×X(n)+(1-α)×Y(n-1)where: Y(n) is the filter output value at the current moment, X(n) is the sampling value at the current moment, Y(n-1) is the filter output value at the previous moment, α is the weight coefficient.

9. The test method of the battery electrolyte leakage and surface temperature test device according to claim 8, characterized in that: The host computer software adjusts the sampling time intervals of the current signal, voltage signal and temperature according to the rate of change of the sampled current value. In the early stage of short circuit, the sampling interval is 0.5s. In the middle stage, as the rate of change of the current data decreases, the sampling interval is 1s. In the late stage, as the rate of change of the current data continues to decrease, the sampling interval is 2s.

10. The test method of the battery electrolyte leakage and surface temperature test device according to claim 7, characterized in that: The temperature control unit adopts improved PID algorithm control, which realizes fast response, reduces overshoot and eliminates steady-state error through the combination of proportional, integral and differential control. The formula is as follows: Δt(n)=Kp×[e(n)-e(n-1)]+Ki×e(n)+Kd×[e(n)-2e(n-1)+e(n-2)] in: Δt(n) is the nth temperature increment, e(n) is the nth error, that is, e(n) = set value - actual temperature value, Kp is the proportional gain, which is 0.

2. Ki is the integral gain, take 0.13, Kd is the differential gain, which is 0.

3. The actual control temperature t(n) is calculated by the increment Δt(n), and the previous temperature is t(n-1). The formula is as follows: t(n)=t(n-1)+Δt(n).

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