Lithium ion battery OCV-DCR cross test method
Through the lithium-ion battery OCV-DCR cross-test method, combined with capacity calibration and cross-test, the problem of time-consuming testing of OCV and DCR in separate tests of lithium-ion batteries is solved, and the effect of simultaneously testing OCV and DCR is achieved, saving testing resources.
Patent Information
- Application Number
- CN202411711978.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-03-07
AI Technical Summary
The static voltage OCV and DC internal resistance DCR of lithium-ion batteries usually need to be tested separately at different temperatures and SOC states, resulting in a lot of testing time.
A lithium-ion battery OCV-DCR cross-test method is proposed. Through capacity calibration, discharge and charge cross-test, combined with data processing calculation, DCR calculation of all temperatures and SOC points is completed.
Without increasing the test time, the battery charge and discharge OCV and charge and discharge DCR can be tested simultaneously, saving testing resources.
Smart Images
Figure CN119575208A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of new energy vehicle power battery systems, and in particular to an OCV-DCR crossover test method for a lithium-ion battery. Background Art
[0002] The static voltage OCV of lithium-ion batteries is an important parameter for battery management systems to estimate SOC. The DC internal resistance DCR of lithium-ion batteries is an important parameter for battery power estimation and battery system simulation. OCV and DCR usually need to be tested separately at different temperatures and SOC states, which takes a lot of testing time. Summary of the invention
[0003] In order to solve the above technical problems, the present invention proposes a lithium-ion battery OCV-DCR crossover test method, which can save test resources.
[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a lithium-ion battery OCV-DCR crossover test method, comprising the following steps: S1: Capacity calibration of the lithium-ion battery to be tested; S2: discharge OCV and DCR cross test; S3: Charging OCV and DCR cross test; S4: Data processing, calculate the DCR of all temperatures and SOC points.
[0005] Furthermore, in S1, under an environment of 25°C±2°C, the battery is discharged to a cut-off voltage at a current of 1I and left for 1 hour; after charging to a cut-off voltage at a current of 1I, the charging is stopped after the current is reduced to 0.05I at a constant voltage, and left for 1 hour; the battery is discharged to a cut-off voltage at a current of 1I and left for 1 hour; the charge and discharge are repeated 3 times, and the last discharge capacity is taken as C0, where I is the nominal 1h discharge current of the lithium-ion battery.
[0006] Furthermore, in S2, at 25°C ± 2°C, after charging to the cut-off voltage with a current of 1I1, the charging is stopped after the current is reduced to 0.05I1 at a constant voltage, the battery is placed at the temperature required for testing to reach thermal equilibrium, the OCV is tested, and the discharge end voltage U is recorded with a nI1 pulse discharge Xs. d ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, discharge it at 1I1 to 95% SOC, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and record the discharge end voltage U at nI1 pulse discharge Xs. d , repeat the above steps until all OCV and DCR tests are completed, where the I1 value is equal to C0.
[0007] Further, in S3, at 25°C ± 2°C, discharge to the cut-off voltage with a current of 1I1, place the battery at the temperature to be tested and leave it to reach thermal equilibrium, test OCV, and record the charge end voltage U with a pulse charge of 1I1 for Xs. C ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, charge it to the next SOC at 1I1, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and charge it with nI1 pulses for Xs to record the end-of-charge voltage U C , repeat the above steps until the OCV and DCR tests of all SOCs are completed, where the I1 value is equal to C0.
[0008] Furthermore, in S4, by discharging DCR=(OCV-U d ) / nI1, charging DCR = (U c -OCV) / nI1, calculate the DCR for all temperatures and SOC points.
[0009] In summary, the beneficial effects of the present invention are: The lithium-ion battery OCV-DCR crossover test method of the present invention can simultaneously test the battery charge and discharge OCV and charge and discharge DCR without increasing the test time, thereby saving test resources. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 It is a schematic diagram of the flow of the lithium-ion battery OCV-DCR crossover test method of the present invention. DETAILED DESCRIPTION
[0011] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0012] See also Figure 1 The present invention provides a lithium-ion battery OCV-DCR crossover test method, comprising the following steps: S1: Capacity calibration of the lithium-ion battery to be tested; S2: discharge OCV and DCR cross test; S3: Charging OCV and DCR cross test; S4: Data processing, calculate the DCR of all temperatures and SOC points.
[0013] Furthermore, in S1, under an environment of 25°C±2°C, the battery is discharged to a cut-off voltage at a current of 1I and left for 1 hour; after charging to a cut-off voltage at a current of 1I, the charging is stopped after the current is reduced to 0.05I at a constant voltage, and left for 1 hour; the battery is discharged to a cut-off voltage at a current of 1I and left for 1 hour; the charge and discharge are repeated 3 times, and the last discharge capacity is taken as C0, where I is the nominal 1h discharge current of the lithium-ion battery.
[0014] Furthermore, in S2, at 25°C ± 2°C, after charging to the cut-off voltage with a current of 1I1, the charging is stopped after the current is reduced to 0.05I1, the battery is placed at the temperature required for testing to reach thermal equilibrium, the OCV is tested, and the discharge end voltage U is recorded with a 1I1 pulse discharge for 10s. d ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, discharge at 1I1 to 95% SOC, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and discharge at 1I1 pulse for 10s to record the discharge end voltage U d , repeat the above steps until all OCV and DCR tests of SOC 100%, 95%, 90%...%5, 0% are completed, where the I1 value is equal to C0.
[0015] Furthermore, in S3, at 25°C ± 2°C, the battery is discharged at a current of 1I1 to a cut-off voltage, the battery is placed at a temperature to be tested and left to reach thermal equilibrium, the OCV is tested, and the charge end voltage U is recorded at a current of 1I1 for 10 seconds. C ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, charge it at 1I1 to the next SOC, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and charge it at 1I1 pulse for 10s to record the end-of-charge voltage U C , repeat the above steps until the OCV and DCR tests of all SOCs are completed, where the I1 value is equal to C0.
[0016] Furthermore, in S4, by discharging DCR=(OCV-U d ) / 1I1, charging DCR = (U c -OCV) / 1I1, calculate the DCR for all temperatures and SOC points.
[0017] The lithium-ion battery OCV-DCR crossover test method of the present invention can simultaneously test the battery charge and discharge OCV and charge and discharge DCR without increasing the test time, thereby saving test resources.
[0018] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.
Claims
1. A lithium-ion battery OCV-DCR crossover test method, characterized in that: The following steps are involved: S1: Capacity calibration of the lithium-ion battery to be tested; S2: discharge OCV and DCR cross test; S3: Charging OCV and DCR cross test; S4: Data processing, calculate the DCR of all temperatures and SOC points.
2. The lithium-ion battery OCV-DCR crossover test method according to claim 1, characterized in that: In S1, under the environment of 25℃±2℃, the battery is discharged to the cut-off voltage with a current of 1I and left for 1 hour; after charging to the cut-off voltage with a current of 1I, the charging is stopped after the current is reduced to 0.05I at a constant voltage, and left for 1 hour; the battery is discharged to the cut-off voltage with a current of 1I and left for 1 hour; the charge and discharge are repeated 3 times, and the last discharge capacity is taken as C0, wherein I is the nominal 1h discharge current of the lithium-ion battery.
3. The lithium-ion battery OCV-DCR crossover test method according to claim 1, characterized in that: In S2, at 25°C ± 2°C, charge to the cut-off voltage with a current of 1I1, then stop charging after the current is reduced to 0.05I1 at a constant voltage, place the battery at the temperature required for testing and leave it to reach thermal equilibrium, test OCV, and record the discharge end voltage U with nI1 pulse discharge Xs. d ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, discharge it at 1I1 to 95% SOC, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and record the discharge end voltage U at nI1 pulse discharge Xs. d , repeat the above steps until all OCV and DCR tests are completed, where the I1 value is equal to C0.
4. The lithium-ion battery OCV-DCR crossover test method according to claim 1, characterized in that: In S3, at 25°C ± 2°C, discharge to the cut-off voltage with a current of 1I1, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and charge with nI1 pulses for Xs to record the charge end voltage U C ; Then, place the battery at 25℃±2℃ to reach thermal equilibrium, charge it to the next SOC at 1I1, place the battery at the temperature required for testing to reach thermal equilibrium, test OCV, and charge it with nI1 pulses for Xs to record the end-of-charge voltage U C , repeat the above steps until the OCV and DCR tests of all SOCs are completed, where the I1 value is equal to C0.
5. The lithium-ion battery OCV-DCR crossover test method according to claim 1, characterized in that: In S4, by discharging DCR=(OCV-U d ) / nI1, charging DCR = (U c -OCV) / nI1, calculate the DCR for all temperatures and SOC points.