A method for rapidly testing the life of a battery for an electric vehicle

Abstract

The application discloses a kind of electric vehicle battery life quick test methods, comprising the following steps: S1: obtaining battery;S2: discharge battery to termination voltage by first current, obtain discharge capacity;Constant voltage and second current are charged for several hours to battery, and the battery is stationary after charging;If discharge capacity is greater than capacity threshold, calculate capacity attenuation rate, repeat step S2, if discharge capacity is not greater than capacity threshold, end test;S3: based on continuous capacity attenuation rate determines whether battery has life problem.The beneficial effects of the present application are: it can shorten the test cycle, quickly determine whether the positive plate has interface problem, simple operation and strong applicability.

Description

Technical Field

[0001] This invention relates to the field of battery life testing technology, and in particular to a rapid testing method for the life of batteries used in electric vehicles. Background Technology

[0002] Currently, lead-acid batteries are widely used in electric vehicles, electric road vehicles, telecommunications, power, portable devices, energy storage, and medical equipment. The variety of battery models for electric vehicles is also increasing, and it's crucial to avoid issues like short riding range and limited lifespan due to battery problems. Therefore, it's necessary to test the lifespan and reliability of new battery products.

[0003] In existing technologies, the testing methods for the lifespan of electric vehicle batteries mainly rely on the vehicle-mounted battery test and the lifespan reliability and cycle life methods in the national standard GB / T22199.1-2017. These national standard testing methods all use time as the termination condition and do not employ discharge to the designed termination voltage of 10.5V for battery performance testing. The national standard charging voltage is 16V, which inevitably leads to severe water loss in the battery, causing it to fail due to electrolyte drying during testing. Therefore, the number of test cycles cannot accurately reflect battery performance, resulting in inaccurate judgments about battery performance. While the vehicle-mounted battery test is highly reliable, including three stages—constant current, constant voltage, and float charging—one cycle test requires approximately 16 hours, which is a relatively long testing period. Existing technologies suffer from the problem of excessively long testing cycles.

[0004] For example, a method for repairing the sulfation of lead-acid batteries disclosed in Chinese patent literature, with publication number CN102157757A and application date of March 10, 2011, can solve the technical problems of cumbersome repair process and excessive repair time of lead-acid batteries in the prior art, but it has the problem of not being able to test the battery life. Summary of the Invention

[0005] To address the shortcomings of existing technologies that cannot test battery life and have excessively long testing cycles, this invention proposes a rapid testing method for the life of batteries used in electric vehicles. This method can shorten the testing cycle, quickly determine whether there are interface problems with the positive electrode plate, and is simple to operate and highly applicable.

[0006] The following is the technical solution of the present invention: a rapid testing method for the life of a battery for electric vehicles, comprising the following steps:

[0007] S1: Obtain the battery;

[0008] S2: Discharge the battery to the termination voltage using the first current to obtain the discharge capacity;

[0009] Charge the battery for several hours using a constant voltage and a second current, and then let the battery stand still after charging.

[0010] If the discharge capacity is greater than the capacity threshold, calculate the capacity decay rate and repeat step S2. If the discharge capacity is not greater than the capacity threshold, end the test.

[0011] S3: Determine whether the battery has a lifespan problem based on the continuous capacity decay rate.

[0012] In this solution, batteries are tested before being put on the market. A test cycle consists of two phases: discharge testing and charging testing. During the discharge test, the battery is discharged to a termination voltage using a first current to obtain the discharge capacity. During the charging test, the battery is charged for several hours using a constant voltage and a second current. After charging, the battery is left to stand, and the relationship between the discharge capacity and a capacity threshold is compared. If the discharge capacity is greater than the capacity threshold, the capacity decay rate is calculated, and the next test cycle begins. If the discharge capacity is not greater than the capacity threshold, the test ends. Based on the continuous capacity decay rate, it is determined whether the battery has a lifespan problem. This method shortens the test cycle, quickly determines whether there are interface problems with the positive electrode plate, and is simple to operate and highly applicable.

[0013] Preferably, in step S2, the first current is 1C, the second current is 0.5C, the termination voltage is 10.5V, the constant voltage is 14.8V, the charging time is 5 hours, the capacity threshold is 0.75C, and the resting time is 1 hour.

[0014] In this scheme, the battery is discharged with a first current of 1C, and the termination voltage is 10.5V, yielding the discharge capacity. The battery is then charged for 5 hours at a constant voltage of 14.8V and a second current of 0.5C, followed by a 1-hour rest period. The relationship between the discharge capacity and the capacity threshold is determined: if the discharge capacity is greater than the capacity threshold, the battery capacity decay rate is calculated, and steps S21 and S22 are repeated; if the discharge capacity is not greater than the capacity threshold, the test ends. The test parameters are: first current 1C, second current 0.5C, termination voltage 10.5V, constant voltage 14.8V, charging time 5 hours, capacity threshold 0.75C, and rest time 1 hour. These test values ​​are optimal and not the only possible values. A controlled variable method is used to conduct a comparative experiment on the first current, second current, termination voltage, constant voltage, and charging time. Using other values ​​would lengthen the experimental period or reduce the accuracy of the test.

[0015] Preferably, in step S2, each discharge test and charge test of the battery constitutes one experimental cycle, with the experimental cycle lasting 6-7 hours.

[0016] In this solution, the test cycle is 6-7 hours, while the vehicle-mounted mode 3-stage cyclic test requires about 16 hours per cycle. This solution can shorten the test cycle.

[0017] As a preferred method, the capacity decay rate is calculated based on the battery capacity after two consecutive experiments. The calculation formula is as follows:

[0018]

[0019] In the formula, p is the capacity decay rate, Q is the capacity of the battery in this experiment, and Q0 is the capacity of the battery. last This refers to the capacity of the battery in the previous experiment.

[0020] In this scheme, the capacity decay rate is calculated based on two adjacent experiments, which increases the amount of capacity decay rate data while ensuring continuity, making it easier to analyze and process, and improving the accuracy of the test.

[0021] As a preferred option, if the capacity decay rate is greater than 1.6% in at least 5 consecutive experiments, the battery has a positive plate interface problem.

[0022] In this scheme, due to the inherent randomness of the test, a single capacity decay rate greater than 1.6% may be caused by accidental or unexpected factors. Therefore, using data from a single test as a basis for judgment is not representative. Furthermore, after a problem occurs at the positive plate interface of the battery, the capacity decay rate in subsequent experiments is consistently greater than 1.6%. This scheme uses a capacity decay rate greater than 1.6% from at least five consecutive tests as the judgment criterion, thus shortening the testing time while ensuring accuracy.

[0023] As a preferred option, if the number of experiments exceeds 300 and there are no five consecutive experiments with a capacity decay rate greater than 1.6%, the battery life is not a problem.

[0024] In this scheme, for normal batteries, the capacity can still be stable after 300 charge-discharge cycles. For batteries with positive plate interface problems, the capacity will show a sharp decline after 250 cycles. Therefore, if the number of experiments exceeds 300 and the capacity decay rate does not exceed 1.6% for 5 consecutive experiments, the battery life is not a problem.

[0025] As a preferred option, the battery is a lead-acid battery.

[0026] The beneficial effects of this invention are: it can quickly determine whether there is an interface problem in the positive electrode plate; it shortens the testing cycle; the testing method has high reliability and strong practicality; and the testing steps are simple and easy to implement. Attached Figure Description

[0027] Figure 1 The present invention provides a flowchart of a rapid testing method for the lifespan of batteries used in electric vehicles.

[0028] Figure 2 The present invention provides a flowchart of the testing phases of a rapid testing method for the lifespan of batteries used in electric vehicles.

[0029] Figure 3 The present invention provides a rapid testing method for the lifespan of batteries used in electric vehicles, and the test results of different batteries are shown in the figure.

[0030] Figure 4 The image shows the test results of a vehicle-mounted mode for a rapid test method of battery life for electric vehicles according to the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0032] Example: Figure 1 As shown, a rapid testing method for the lifespan of batteries used in electric vehicles includes the following steps:

[0033] S1: Obtain the battery;

[0034] S2: Discharge the battery to the termination voltage using the first current to obtain the discharge capacity; charge the battery for several hours using a constant voltage and the second current, and then let the battery stand still after charging; if the discharge capacity is greater than the capacity threshold, calculate the capacity decay rate and repeat step S2; if the discharge capacity is not greater than the capacity threshold, end the test.

[0035] S3: Determine whether the battery has a lifespan problem based on the continuous capacity decay rate.

[0036] S1: Obtain the battery.

[0037] Specifically, the battery is a lead-acid battery. Since the battery is pre-filled with electrolyte at the factory and is not easily disassembled, users generally cannot add electrolyte. Therefore, a life test is conducted on the battery before it is released to the market. By obtaining the battery's actual parameters through testing and comparing these parameters with the design parameters, it can be determined whether the battery meets the usage requirements. This avoids a high return rate due to inaccurate life test results when the battery is shipped to the market.

[0038] S2: Discharge the battery to the termination voltage using the first current to obtain the discharge capacity; charge the battery for several hours using a constant voltage and the second current, and then let the battery stand still after charging; if the discharge capacity is greater than the capacity threshold, calculate the capacity decay rate and repeat step S2; if the discharge capacity is not greater than the capacity threshold, end the test.

[0039] Specifically, the battery life performance is quickly tested according to the designed termination voltage, so as to accurately reflect the battery life performance and avoid the return rate from being high when the batteries are sent to the market due to inaccurate life test results.

[0040] S21: Discharge with a first current of 1C, the battery's termination voltage is 10.5V, and the discharge capacity is obtained.

[0041] S22: Charge the battery for 5 hours at a constant voltage of 14.8V and a second current of 0.5C, and then let the battery stand for 1 hour after charging.

[0042] S23: Determine the relationship between discharge capacity and capacity threshold: If the discharge capacity is greater than the capacity threshold, calculate the battery capacity decay rate and repeat steps S21 and S22; if the discharge capacity is not greater than the capacity threshold, end the test.

[0043] In the test, the first current was 1C, the second current was 0.5C, the termination voltage was 10.5V, the constant voltage was 14.8V, the charging time was 5 hours, the capacity threshold was 0.75C, and the resting time was 1 hour. Under these conditions, the experimental cycle for one discharge and charge test was 6-7 hours, ensuring test accuracy. These test values ​​are optimal and not the only possible values. A controlled variable method was used to conduct a comparative experiment on the first current, second current, termination voltage, constant voltage, and charging time. If other values ​​were used, the experimental cycle would exceed 7 hours or the test accuracy would decrease.

[0044] S3: Determine whether the battery has a lifespan problem based on the continuous capacity decay rate.

[0045] Specifically, in step S2, each discharge and charge test of the battery is considered as one experimental cycle. The capacity of the battery in this experiment and the capacity of the battery in the previous experiment are obtained respectively. The capacity decay rate is calculated based on the difference between the two capacities, and the calculation formula is as follows:

[0046]

[0047] In the formula, p is the capacity decay rate, Q is the capacity of the battery in this experiment, and Q0 is the capacity of the battery. last This refers to the capacity of the battery in the previous experiment.

[0048] If the capacity decay rate is greater than 1.6% in at least 5 consecutive experiments, then a problem with the positive electrode interface is identified.

[0049] Using a 1C discharge current allows for timely detection of interface problems on the positive electrode plate. If there are issues at the interface between the positive electrode plate grid and the active material, the interface resistance will increase. During the initial stages of cycling, the voltage will drop to 10.5V very quickly during discharge and reach 14.8V very quickly during charging. The curing effect significantly impacts interface performance; therefore, this method allows for rapid detection of whether the positive electrode plate is properly cured.

[0050] After comparative testing of different new battery products, such as Figure 3As shown: if the number of experiments exceeds 300 and the battery capacity does not decrease, that is, if the capacity decay rate is not greater than 1.6% for 5 consecutive experiments, the battery life is considered to be fine; if there is a problem with the positive plate interface, the capacity will show a sharp decline after 250 experiments.

[0051] like Figure 4 As shown: the battery samples tested using the vehicle-mounted mode in the same batch yielded results consistent with those of this invention. The experimental cycle of the above test was 6-7 hours, while one cycle of the vehicle-mounted mode 3-stage cyclic test required approximately 16 hours.

[0052] This system allows for rapid testing of battery life performance at the designed cutoff voltage, providing accurate feedback on battery life and preventing high return rates due to inaccurate life testing when batteries are shipped to the market. It also shortens the overall charge-discharge cycle testing time, accelerating the development of new products in the industry and solving the bottleneck problem of lengthy life testing times.

Claims

1. A rapid testing method for the lifespan of batteries used in electric vehicles, characterized in that, Includes the following steps: S1: Obtain the battery; S2: Discharge the battery to the termination voltage using the first current to obtain the discharge capacity; Charge the battery for several hours using a constant voltage and a second current, and then let the battery stand still after charging. Each discharge and charge test of the battery constitutes one experimental cycle. If the discharge capacity is greater than the capacity threshold, calculate the capacity decay rate. The capacity decay rate is calculated based on the battery capacity after two consecutive experiments, and is as follows: Capacity decay rate = 1 - Capacity of the battery in this experiment / Capacity of the battery in the previous experiment; Repeat step S2. If the discharge capacity is not greater than the capacity threshold, end the test. S3: Determine whether the battery has a lifespan problem based on the continuous capacity decay rate.

2. The method for rapid testing of the lifespan of a battery for electric vehicles according to claim 1, characterized in that, In step S2, the first current is 1C, the second current is 0.5C, the termination voltage is 10.5V, and the constant voltage is 14.8V.

3. The method for rapid testing of the lifespan of a battery for electric vehicles according to claim 1, characterized in that, In step S2, the experimental period is 6-7 hours.

4. The rapid testing method for the lifespan of a battery for electric vehicles according to claim 2, characterized in that, In step S2, the charging time is 5 hours, the capacity threshold is 0.75C, and the resting time is 1 hour.

5. A rapid testing method for the lifespan of a battery for electric vehicles according to claim 1 or 4, characterized in that, If the capacity decay rate is greater than 1.6% in at least 5 consecutive experiments, the battery has a positive plate interface problem.

6. The method for rapid testing of the lifespan of a battery for electric vehicles according to claim 1, characterized in that, If the number of experiments exceeds 300 and there are no five consecutive experiments with a capacity decay rate greater than 1.6%, the battery life is not a problem.

7. The rapid testing method for the lifespan of a battery for electric vehicles according to claim 1, characterized in that, The battery is a lead-acid battery.

Images