Battery self-discharge test system and method

Abstract

The invention relates to a battery self-discharge test system and method, and the system comprises a heat insulation device which comprises a heat insulation cavity and a temperature sensor, and a to-be-tested battery cell and the temperature sensor are disposed in the heat insulation cavity; the self-discharge tester comprises a processor, a voltage reference source, an ADC unit, a DAC unit, a switch 1 and a switch 2, the voltage reference source is connected with the ADC unit and the DAC unit; the processor is connected with the control ends of the switch 1 and the switch 2 and is used for controlling switching of the switch 1 and the switch 2; the processor is connected with the input end of the DAC unit, the output end of the DAC unit is connected with the first end of the switch 1 and the first end of the switch 2 after passing through the voltage buffer, and the current detection end of the voltage buffer is connected with the current sampling end of the ADC unit; the second end of the switch 1 is connected with a to-be-tested cell, the second end of the switch 2 is connected with the to-be-tested cell, and the third end of the switch 2 is connected with the voltage input end of the ADC; the temperature sensor is connected with the processor and used for collecting the temperature in the heat insulation cavity. And the upper computer is connected with the processor.

Description

Technical Field

[0001] The present invention relates to the technical field of battery self-discharge testing, and particularly relates to a battery self-discharge testing system and method. Background Art

[0002] After the battery is produced, due to objective practical problems such as principle defects, production process differences, or raw material technical levels, the battery has a self-discharge phenomenon, resulting in power loss during long-term storage. Therefore, after the battery is produced, it is necessary to detect the leakage current of the battery to determine whether the battery is qualified. At the same time, at the battery usage terminal, it is also necessary to classify the leakage current levels of the batteries. When the batteries are used in parallel, it is necessary to select batteries with similar leakage currents. Otherwise, if the difference in battery leakage currents is too large, the battery capacity of the entire battery pack will be leaked.

[0003] The currently common method for detecting the leakage current of a battery is to place the battery at room temperature for a period of time, generally one to two weeks, and in some cases up to a month or even longer, and then measure the voltage change of the battery during this period, and calculate the leakage current of the battery accordingly. However, this method for detecting the leakage current of a battery has a long test time and low accuracy of the measured leakage current. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a battery self-discharge testing system and method, aiming to solve the problems of long test time and low test accuracy of the existing battery leakage current detection method.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, a battery self-discharge testing system includes:

[0007] A heat insulation device, including: a heat insulation chamber and a temperature sensor, and the battery cell to be tested and the temperature sensor are installed in the heat insulation chamber;

[0008] A self-discharge tester, including: a processor, a voltage reference source, an ADC unit, a DAC unit, switch 1 and switch 2;

[0009] The voltage reference source is connected to the ADC unit and the DAC unit, and is used to provide a reference voltage for the ADC unit and the DAC unit; the processor is connected to the control ends of the switch 1 and the switch 2, and is used to control the switching of the switch 1 and the switch 2; the processor is connected to the input end of the DAC unit, the output end of the DAC unit is connected to the first ends of the switch 1 and the switch 2 after passing through the voltage buffer, and the current detection end of the voltage buffer is connected to the current sampling end of the ADC unit; the second end of the switch 1 is connected to the battery cell to be measured, the second end of the switch 2 is connected to the battery cell to be measured, and the third end of the switch 2 is connected to the voltage input end of the ADC; the temperature sensor is connected to the processor and is used to collect the temperature in the heat insulation chamber;

[0010] The upper computer is connected to the processor.

[0011] In a second aspect, a method for testing the self-discharge of a battery includes the following steps:

[0012] Step 1: Place the battery cell to be measured in the heat insulation chamber, and the processor collects the temperature of the battery cell to be measured in real time through the temperature sensor;

[0013] Step 2: The processor disconnects the switch 1 and switches the switch 2 to the second end. The ADC unit measures the open-circuit voltage V BAT of the battery cell to be measured, and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor;

[0014] Step 3: After the processor obtains the open-circuit voltage V BAT of the battery cell to be measured, the processor switches the switch 2 to the third end, and then the processor controls the DAC unit to generate an excitation voltage V DAC . The ADC unit measures the excitation voltage V DAC generated by the DAC unit, and converts the excitation voltage V DAC into a digital quantity and records it by the processor;

[0015] Step 4: The processor compares the collected excitation voltage V DAC with the collected open-circuit voltage V BAT ;

[0016] Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 of the resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through the approximation adjustment algorithm, and repeats step 4 until the excitation voltage V DAC and the open-circuit voltage V BATIf the difference is less than or equal to 1 / 2 of the resolution of the DAC unit, proceed to the next step;

[0017] Step 6: The processor controls switch 1 to turn on, connecting the excitation voltage V DAC and the open-circuit voltage V BAT ;

[0018] Step 7: The processor continuously acquires the excitation current output by the DAC unit through the ADC unit until the excitation current tends to a stable value, and the stable excitation current is the self-discharge current of the battery cell under test.

[0019] Further, in Step 1, place the battery cell under test in the heat insulation chamber, let it stand until the temperature is stable, then connect the heat insulation device, the self-discharge tester and the host computer, and the system is powered on for a preset time to complete preheating.

[0020] Further, in Step 5, the processor adjusts the excitation voltage V generated by the DAC unit through the approximation adjustment algorithm. DAC The specific method is that the processor adjusts the excitation voltage V successively from the high bit to the low bit with the resolution step of the DAC unit. DAC until it converges to the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit.

[0021] Further, in Steps 6 and 7, after the processor controls switch 1 to turn on, it delays for a preset time. After the circuit is stable, the processor then continuously acquires the excitation current output by the DAC unit through the ADC unit to avoid transient interference.

[0022] In a third aspect, a method for testing the self-discharge of a battery includes the following steps:

[0023] Step 1: Place the battery cell under test in the heat insulation chamber, and the processor continuously acquires the temperature of the battery cell under test through the temperature sensor;

[0024] Step 2: The processor disconnects switch 1 and switches switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V of the battery cell under test. BAT and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor;

[0025] Step 3: After the processor obtains the open-circuit voltage V of the battery cell under test. BAT the processor switches switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V. DAC The ADC unit measures the excitation voltage V generated by the DAC unit. DAC and converts the excitation voltage V DAC into a digital quantity and records it by the processor;

[0026] Step 4: The processor compares the collected excitation voltage V DAC with the collected open-circuit voltage V BAT .

[0027] Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 of the resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm, and repeats Step 4 until the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit, then proceed to the next step;

[0028] Step 6: The processor controls switch 1 to close, connecting the excitation voltage V DAC and the open-circuit voltage V BAT .

[0029] Step 7: Since the excitation current will increase as the excitation voltage V DAC increases, the processor adjusts the starting excitation voltage V DAC of the DAC unit to make the starting excitation current V DAC tend to the qualified judgment threshold of the self-discharge current of the battery under test, and then maintain a constant voltage excitation to shorten the test time;

[0030] Step 8: After the battery under test is excited by voltage, the processor continuously detects the excitation current to determine whether the excitation current is gradually increasing or decreasing;

[0031] Step 9: If the excitation current gradually increases, it is considered that the self-discharge current is greater than the threshold. If the excitation current gradually decreases, it is considered that the self-discharge current is less than the threshold, thereby judging the magnitude relationship between the self-discharge current and the excitation current of the battery under test.

[0032] Furthermore, in Step 1, the battery under test is placed in a heat-insulating chamber and left to stand until the temperature stabilizes. Then, the heat-insulating device, the self-discharge tester, and the upper computer are connected, and the system is powered on for a preset time to complete preheating.

[0033] Furthermore, in Step 5, the specific way for the processor to adjust the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm is that the processor adjusts the excitation voltage V DAC from high to low in steps of the resolution of the DAC unit until it converges to the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit.

[0034] Further, in steps 6 and 7, after the processor turns on switch 1, it delays for a preset time. After the circuit stabilizes, the processor continuously collects the excitation current output by the DAC unit through the ADC unit to avoid transient interference.

[0035] A battery self-discharge test system and method described in the present invention have the beneficial effects that:

[0036] By isolating external temperature fluctuations through a heat insulation chamber and combining with real-time monitoring by a temperature sensor, it ensures that the temperature change in the test environment is < ±0.1°C. The voltage reference source provides an independent reference voltage for the ADC / DAC to ensure the stability of sampling and quantization; the processor measures the open-circuit voltage of the battery under test by disconnecting switch 1 and switching switch 2 to the second terminal, and then switches switch 2 to the third terminal to detect the difference between the excitation voltage and the open-circuit voltage to measure the excitation current. The test parameters are remotely configured through the host computer, and the data is stored in real time, supporting batch testing and big data analysis, shortening the battery self-discharge test time and improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the battery self-discharge test system according to an embodiment of the present invention;

[0038] Figure 2 is a schematic flowchart of the battery self-discharge test method in the standard test mode according to an embodiment of the present invention;

[0039] Figure 3 is a schematic flowchart of the battery self-discharge test method in the fast test mode according to an embodiment of the present invention;

[0040] Figure 4 is a waveform diagram of the excitation circuit data measured by the battery self-discharge test method in the standard test mode according to an embodiment of the present invention;

[0041] Figure 5 is a waveform diagram of the excitation circuit data measured by the battery self-discharge test method in the fast test mode according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0043] As shown in the figure, the present invention provides a battery self-discharge test system, including:

[0044] A heat insulation device, including: a heat insulation chamber and a temperature sensor, and the battery under test and the temperature sensor are installed in the heat insulation chamber;

[0045] A self-discharge tester, including: a processor, a voltage reference source, an ADC unit, a DAC unit, a switch 1 and a switch 2;

[0046] The voltage reference source is connected to the ADC unit and the DAC unit, and is used to provide a reference voltage for the ADC unit and the DAC unit; the processor is connected to the control ends of switch 1 and switch 2, and is used to control the switching of switch 1 and switch 2; the processor is connected to the input end of the DAC unit, the output end of the DAC unit is connected to the first ends of switch 1 and switch 2 after passing through a voltage buffer, the current detection end of the voltage buffer is connected to the current sampling end of the ADC unit; the second end of switch 1 is connected to the battery cell to be tested, the second end of switch 2 is connected to the battery cell to be tested, and the third end of switch 2 is connected to the voltage input end of the ADC; the temperature sensor is connected to the processor and is used to collect the temperature in the heat insulation cavity;

[0047] The host computer is connected to the processor.

[0048] The external temperature fluctuation is isolated through the heat insulation cavity, and combined with the real-time monitoring of the temperature sensor, it is ensured that the temperature change in the test environment is <±0.1 °C, eliminating the influence of temperature on the open-circuit voltage of the battery cell. The voltage reference source provides an independent reference voltage for the ADC / DAC, ensuring the stability of sampling and quantization; the processor measures the open-circuit voltage of the battery cell to be tested by disconnecting switch 1 and switching switch 2 to the second end, and then switches switch 2 to the third end to detect the difference between the excitation voltage and the open-circuit voltage, realizing the measurement of the excitation current. The voltage buffer can prevent the load effect and ensure the stability of the excitation voltage. The test parameters are remotely configured through the host computer, and the data is stored in real time, supporting batch testing and big data analysis, shortening the battery self-discharge test time and improving the test accuracy.

[0049] Such as Figure 2 shown, the battery self-discharge test system includes two battery self-discharge test methods, one is the standard test mode, and the other is the fast test mode.

[0050] The battery self-discharge test method in the standard test mode includes the following steps:

[0051] Step 1: Place the battery cell to be tested in the heat insulation cavity, and the processor collects the temperature of the battery cell to be tested in real time through the temperature sensor;

[0052] Step 2: The processor disconnects switch 1 and switches switch 2 to the second end, and the ADC unit measures the open-circuit voltage V BAT of the battery cell to be tested, and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor;

[0053] Step 3: After the processor obtains the open-circuit voltage V BAT of the battery cell to be tested, the processor switches switch 2 to the third end, and then the processor controls the DAC unit to generate an excitation voltage V DAC , and the ADC unit measures the excitation voltage V generated by the DAC unitDAC and convert the excitation voltage V DAC into a digital quantity and record it by the processor;

[0054] Step 4: The processor compares the collected excitation voltage V DAC with the collected open-circuit voltage V BAT ;

[0055] Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm, and repeats Step 4 until the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 resolution of the DAC unit, then proceed to the next step;

[0056] Step 6: The processor controls switch 1 to be turned on to connect the excitation voltage V DAC and the open-circuit voltage V BAT ;

[0057] Step 7: The processor continuously collects the excitation current output by the DAC unit through the ADC unit until the excitation current tends to a stable value, and the stable excitation current is the self-discharge current of the battery cell to be measured.

[0058] As Figure 3 shown, the battery self-discharge test method in fast test mode includes the following steps:

[0059] Step 1: Place the battery cell to be measured in a heat-insulating chamber, and the processor collects the temperature of the battery cell to be measured in real time through a temperature sensor;

[0060] Step 2: The processor disconnects switch 1 and switches switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V BAT of the battery cell to be measured, and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor;

[0061] Step 3: After the processor obtains the open-circuit voltage VBAT of the battery cell to be measured, the processor switches switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V DAC . The ADC unit measures the excitation voltage V DAC generated by the DAC unit, and converts the excitation voltage V DAC into a digital quantity and records it by the processor;

[0062] Step 4: The processor compares the collected excitation voltage V DAC with the collected open-circuit voltage VBAT Compare;

[0063] Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 of the resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm, and repeats Step 4 until the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit, then proceed to the next step;

[0064] Step 6: The processor controls Switch 1 to turn on, connecting the excitation voltage V DAC and the open-circuit voltage V BAT ;

[0065] Step 7: Since the excitation current will increase as the excitation voltage V DAC increases, the processor adjusts the starting excitation voltage V DAC of the DAC unit, making the starting excitation current V DAC tend to the qualified judgment threshold of the self-discharge current of the battery under test, and then maintaining a constant voltage excitation to shorten the test time;

[0066] Step 8: After the battery under test is excited by the voltage, the processor continuously detects the excitation current and determines whether the excitation current is gradually increasing or gradually decreasing;

[0067] Step 9: If the excitation current gradually increases, it is considered that the self-discharge current is greater than the threshold. If the excitation current gradually decreases, it is considered that the self-discharge current is less than the threshold, thereby judging the magnitude relationship between the self-discharge current and the excitation current of the battery under test.

[0068] Furthermore, in Step 1, place the battery under test in a heat-insulating chamber, let it stand until the temperature is stable, then connect the heat-insulating device, the self-discharge tester and the upper computer, and the system is powered on for a preset time to complete preheating.

[0069] Through the above preparations, the circuit of the self-discharge tester can be stabilized and the measurement error can be reduced.

[0070] Furthermore, in Step 5, the specific way for the processor to adjust the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm is that the processor adjusts the excitation voltage V DAC from high to low in steps of the resolution of the DAC unit until it converges to the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit.

[0071] Further, in steps 6 and 7, after the processor turns on switch 1, it delays for a preset time. After the circuit stabilizes, the processor continuously collects the excitation current output by the DAC unit through the ADC unit to avoid transient interference.

[0072] The following is the test process of the battery self-discharge test system using the battery self-discharge test method in the standard test mode and the fast test mode to perform self-discharge tests on the battery cells to be tested.

[0073] The test process of the battery self-discharge test system using the battery self-discharge test method in the standard test mode to perform self-discharge tests on the battery cells to be tested is as follows:

[0074] (1) Place the battery to be tested in the heat insulation chamber, let it stand until the temperature stabilizes, then connect the heat insulation device, the self-discharge tester and the upper computer, and the system is powered on for a preset time to complete preheating;

[0075] (2) The processor disconnects switch 1 and switches switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V BAT = 3.6440276V of the battery cell to be tested, and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor;

[0076] (3) After the processor obtains the open-circuit voltage V BAT of the battery cell to be tested, the processor switches switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V DAC1 = 3.6440232V. The ADC unit measures the excitation voltage V DAC generated by the DAC unit, and converts the excitation voltage V DAC into a digital quantity and records it by the processor;

[0077] (4) The processor compares the collected excitation voltage V DAC1 with the collected open-circuit voltage V BAT . The difference between the excitation voltage V DAC1 and the open-circuit voltage V BAT is 0.0000042V, and the resolution of the DAC is 0.0000025V, which does not meet the system voltage difference requirement. The processor controls the excitation voltage V DAC generated by the DAC unit to increase by 0.000005V based on V DAC1 to obtain V DAC2 = 3.6440282V. The processor compares the collected excitation voltage V DAC2 with the collected open-circuit voltage V BAT . The difference between the excitation voltage V DAC2 and the open-circuit voltage V BAT is 0.0000006V, which is less than 1 / 2 of the resolution of the DAC unit;

[0078] (5) After completing the V setting of the DAC unit, the processor maintains the V voltage constant and turns on Switch 1 to connect V and V. DAC After the V voltage is set, the processor keeps the V voltage constant and turns on Switch 1 to connect V. DAC and V. DAC and V BAT are connected.

[0079] (6) The processor continuously collects the excitation current output by the DAC unit through the ADC unit until the excitation current tends to a stable value. The actual current data is shown as follows. The stable excitation current is the self-discharge current of the battery under test. The final stable current is about 30 μA, which is the self-discharge current of the battery cell. Figure 4 In this example, during the entire test process, the maximum value of the collected temperature is 24.58 °C, the minimum value is 24.51 °C, and the temperature change range < 0.1 °C. It is considered that the test data of this time is valid.

[0080] In this example, after 1.5 h (5400 s), the test current is 28.5 μA, with a 5% deviation from the final result, greatly shortening the test time of self-discharge.

[0081] In this example, after 1.5 h (5400 s), the test current is 28.5 μA, with a 5% deviation from the final result, greatly shortening the test time of self-discharge.

[0082] The test process of the battery self-discharge test system using the battery self-discharge test method in fast test mode to perform self-discharge test on the battery cell under test is as follows:

[0083] (1) Place the battery under test in the heat insulation chamber, let it stand until the temperature is stable, then connect the heat insulation device, the self-discharge tester and the host computer, and the system is powered on for a preset time to complete preheating.

[0084] (2) The processor disconnects Switch 1 and switches Switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V of the battery cell under test = 3.6440152 V, and converts the open-circuit voltage V into a digital quantity and records it by the processor. BAT = 3.6440152 V, and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor.

[0085] (3) After the processor obtains the open-circuit voltage V of the battery cell under test, the processor switches Switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V = 3.6440155 V. The ADC unit measures the excitation voltage V generated by the DAC unit, and converts the excitation voltage V into a digital quantity and records it by the processor. BAT After the processor obtains the open-circuit voltage V of the battery cell under test, the processor switches Switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V DAC1 = 3.6440155 V. The ADC unit measures the excitation voltage V generated by the DAC unit, DAC and the excitation voltage V DAC is converted into a digital quantity and recorded by the processor.

[0086] (4) The processor compares the collected excitation voltage V DAC1 and the collected open-circuit voltage V BAT . The excitation voltage V DAC1The difference from the open-circuit voltage V BAT is 0.0000003V. The resolution of the DAC is 0.0000025V, which is less than 1 / 2 of the resolution of the DAC unit, meeting the system voltage difference requirement;

[0087] (5) After completing the V DAC voltage setting of the DAC unit, the processor maintains the V DAC voltage constant and turns on switch 1 to connect V DAC and V BAT ;

[0088] (6) The processor continuously collects the excitation current output by the DAC unit through the ADC unit. At this time, the excitation current value is 0.3uA. Then, gradually increase the excitation voltage V DAC , until the excitation current output by the DAC unit is close to 30uA measured in the standard test mode. In this example, it is 29.8uA. Then, maintain the excitation voltage V DAC constant;

[0089] (7) The processor continuously collects the excitation current output by the DAC unit through the ADC unit, and tests the actual current data as Figure 5 shown. In the data collected this time, the current change within 0.5h (1800S) is <1uA. Through the collection within 0.5h, it can be quickly determined that the leakage current of the battery under test is in the range of 29.8±1uA.

[0090] In this example, during the entire test process, the maximum value of the collected temperature is 24.56°C, and the minimum value is 24.52°C. The temperature change range <0.1°C, and it is considered that the test data this time is valid.

[0091] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A battery self-discharge test system, characterized in that, Comprising: A heat insulation device, comprising: a heat insulation cavity and a temperature sensor, and the cell under test and the temperature sensor are installed in the heat insulation cavity; A self-discharge tester, comprising: a processor, a voltage reference source, an ADC unit, a DAC unit, a voltage buffer, switch 1 and switch 2; The voltage reference source is connected to the ADC unit and the DAC unit for providing a reference voltage to the ADC unit and the DAC unit; the processor is connected to the control ends of switch 1 and switch 2 for controlling the switching of switch 1 and switch 2; the processor is connected to the input end of the DAC unit, the output end of the DAC unit is connected to the first ends of switch 1 and switch 2 via the voltage buffer, and the current detection end of the voltage buffer is connected to the current sampling end of the ADC unit; the second end of switch 1 is connected to the cell under test, the second end of switch 2 is connected to the cell under test, and the third end of switch 2 is connected to the voltage input end of the ADC; the temperature sensor is connected to the processor for collecting the temperature in the heat insulation cavity; A host computer, connected to the processor.

2. A method for testing the self-discharge of a battery, characterized in that, Comprising the following steps: Step 1: Place the cell under test in the heat insulation cavity, and the processor collects the temperature of the cell under test in real time through the temperature sensor; Step 2: The processor disconnects switch 1 and switches switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V of the cell under test BAT , and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor; Step 3: The processor obtains the open-circuit voltage V of the battery cell to be measured BAT After that, the processor switches switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V DAC , and the ADC unit measures the excitation voltage V generated by the DAC unit DAC , and converts the excitation voltage V DAC into a digital quantity and records it by the processor; Step 4: The processor compares the acquired excitation voltage V DAC with the acquired open-circuit voltage V BAT ; Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 of the resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through the approximation adjustment algorithm, and repeats Step 4 until the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit, then proceed to the next step; Step 6: The processor controls switch 1 to turn on, connecting the excitation voltage V DAC and the open-circuit voltage V BAT ; Step 7: The processor continuously collects the excitation current output by the DAC unit through the ADC unit until the excitation current tends to a stable value, and the stable excitation current is the self-discharge current of the cell under test.

3. The battery self-discharge test method according to claim 2, characterized in that In Step 1, place the battery under test in the heat insulation cavity, let it stand until the temperature is stable, then connect the heat insulation device, the self-discharge tester and the host computer, and the system is powered on for a preset time to complete preheating.

4. The battery self-discharge test method according to claim 2, wherein, In step 5, the processor adjusts the excitation voltage V generated by the DAC unit through an approximation adjustment algorithm DAC in a specific way that the processor sequentially adjusts the excitation voltage V from the high bit to the low bit with the resolution step of the DAC unit DAC until it converges to the excitation voltage V DAC and the difference from the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit.

5. The battery self-discharge test method according to claim 2, wherein, In Steps 6 and 7, after the processor controls switch 1 to be turned on, it delays for a preset time. After the circuit is stable, the processor then continuously collects the excitation current output by the DAC unit through the ADC unit to avoid transient interference.

6. A method for testing the self-discharge of a battery, characterized in that, Comprising the following steps: Step 1: Place the cell under test in the heat insulation cavity, and the processor collects the temperature of the cell under test in real time through the temperature sensor; Step 2: The processor disconnects switch 1 and switches switch 2 to the second terminal. The ADC unit measures the open-circuit voltage V of the battery cell to be measured BAT , and converts the open-circuit voltage V BAT into a digital quantity and records it by the processor; Step 3: The processor obtains the open-circuit voltage V of the cell under test BAT After that, the processor switches switch 2 to the third terminal, and then the processor controls the DAC unit to generate an excitation voltage V DAC , and the ADC unit measures the excitation voltage V generated by the DAC unit DAC , and converts the excitation voltage V DAC into a digital quantity and records it by the processor; Step 4: The processor compares the acquired excitation voltage V DAC with the acquired open-circuit voltage V BAT ; Step 5: If the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is greater than 1 / 2 resolution of the excitation voltage V DAC , the processor adjusts the excitation voltage V DAC generated by the DAC unit through an approximation adjustment algorithm, and repeats Step 4 until the difference between the excitation voltage V DAC and the open-circuit voltage V BAT is less than or equal to 1 / 2 resolution of the DAC unit, then proceed to the next step; Step 6: The processor controls switch 1 to turn on, connecting the excitation voltage V DAC and the open-circuit voltage V BAT ; Step 7: Since the excitation voltage V DAC increases, the excitation current will become larger. Therefore, the processor adjusts the starting excitation voltage V DAC of the DAC unit, so that the starting excitation current V DAC tends to the qualified judgment threshold of the self-discharge current of the cell to be measured, and then maintains a constant voltage excitation to shorten the test time; Step 8: After the cell under test is voltage-excited, the processor continuously detects the excitation current to judge whether the excitation current is gradually increasing or gradually decreasing; Step 9: If the excitation current gradually increases, it is considered that the self-discharge current is greater than the threshold value. If the excitation current gradually decreases, it is considered that the self-discharge current is less than the threshold value, thereby judging the magnitude relationship between the self-discharge current and the excitation current of the cell under test.

7. The battery self-discharge test method according to claim 6, wherein In Step 1, place the battery under test in the heat insulation cavity, let it stand until the temperature is stable, then connect the heat insulation device, the self-discharge tester and the host computer, and the system is powered on for a preset time to complete preheating.

8. The battery self-discharge test method according to claim 6, wherein, In step 5, the processor adjusts the excitation voltage V generated by the DAC unit through an approximation adjustment algorithm. DAC The specific method is that the processor adjusts the excitation voltage V step by step from the high bit to the low bit with the resolution step of the DAC unit. DAC until it converges to the excitation voltage V DAC The difference from the open-circuit voltage V BAT is less than or equal to 1 / 2 of the resolution of the DAC unit.

9. The battery self-discharge test method according to claim 6, wherein, In Steps 6 and 7, after the processor controls switch 1 to be turned on, it delays for a preset time. After the circuit is stable, the processor then continuously collects the excitation current output by the DAC unit through the ADC unit to avoid transient interference.

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