CN117269770A - Battery pack service life assessment method and system - Google Patents
Battery pack service life assessment method and system Download PDFInfo
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- 230000036541 health Effects 0.000 claims abstract description 96
- 238000012360 testing method Methods 0.000 claims abstract description 48
- 238000001514 detection method Methods 0.000 claims abstract description 23
- 230000014759 maintenance of location Effects 0.000 claims description 13
- 238000004364 calculation method Methods 0.000 claims description 11
- 238000013213 extrapolation Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 5
- 238000010276 construction Methods 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000011156 evaluation Methods 0.000 claims description 3
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- 238000002474 experimental method Methods 0.000 abstract description 7
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- 230000036449 good health Effects 0.000 description 2
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/005—Testing of electric installations on transport means
- G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
- G01R31/007—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks using microprocessors or computers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/392—Determining battery ageing or deterioration, e.g. state of health
Abstract
The invention relates to a battery pack service life assessment method and a system, comprising the following steps: constructing a plurality of reference groups, wherein each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, and the health degree of at least one battery is different between different reference groups; performing charge and discharge tests on the batteries in each reference group to obtain the cycle life of the corresponding reference group; establishing a database, wherein the database comprises a plurality of groups of detection data, and each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group; obtaining a to-be-tested group, wherein the to-be-tested group comprises a plurality of to-be-tested batteries connected in series, and recording the health degree of the to-be-tested batteries; inquiring a database according to the health degree of the batteries to be tested of the group to be tested, and calculating the cycle life of the group to be tested according to the cycle life of the reference group. The method can more accurately and effectively predict the cycle life of the battery pack assembled by batteries with different health degrees, and reduce the experiment cost.
Description
Technical Field
The invention relates to the technical field of battery detection, in particular to a battery pack service life assessment method and system.
Background
The electric power supply system device of the new energy automobile is a battery pack assembled with the electric power supply system device. The battery pack is formed by assembling a plurality of batteries in a serial-parallel connection mode and a plurality of modules in a serial-parallel connection mode. The manufacturing process of the battery has certain fluctuation, so that the battery performance has certain difference; in addition, the capacity, the resistance and the use temperature of the battery in the same new energy automobile are different to some extent, so that the attenuation condition of the battery is also different. When a certain battery in the new energy automobile is abnormal, the experience of the whole new energy automobile is deteriorated, and even safety problems can occur.
At present, when a single battery in a new energy automobile is abnormal, in many cases, only a single module containing the abnormal battery in the battery or a single abnormal battery is replaced. In this case, the state of health of the original battery and the newly replaced battery in the whole vehicle is different, and the life of the battery pack is difficult to evaluate. If batteries with different health degrees are artificially selected to be assembled into a battery pack, the service life of the battery pack is tested through experiments, and as the batteries in the battery pack are more, the influence factors are more, and the test error is larger; and the battery pack is large in size, and the resource cost of test equipment and the like is high, so that the test cost is high.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the technical defects that the service lives of battery packs consisting of batteries with different health degrees in the prior art cannot be estimated and obtained and the test cost is high.
In order to solve the above technical problems, the present invention provides a battery pack life assessment method, including:
constructing a plurality of reference groups, wherein each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, and the health degree of at least one battery is different between different reference groups;
performing charge and discharge tests on the batteries in each reference group, and respectively recording the charge and discharge cycle number and the capacity retention rate after each charge and discharge cycle of the batteries in the reference group to obtain the cycle life of the corresponding reference group;
establishing a database, wherein the database comprises a plurality of groups of detection data, and each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group;
acquiring a to-be-tested group, wherein the to-be-tested group comprises a plurality of batteries to be tested which are connected in series, and recording the health degree of the batteries to be tested;
inquiring a database according to the health degree of the batteries to be tested of the group to be tested, and calculating the cycle life of the group to be tested according to the cycle life of the reference group.
In one embodiment of the present invention, the number of batteries in the to-be-tested group is the same as the number of batteries in the reference group, and the health degree of each battery in the to-be-tested group is set in one-to-one correspondence with the health degree of the battery in the reference group.
In one embodiment of the present invention, the reference group and the test group are two batteries.
In one embodiment of the invention, the two cells of the reference group are denoted as a first cell and a second cell;
the health degree of the first batteries in the plurality of reference groups is the same, and the health degree of the second batteries in the plurality of reference groups is changed in a gradient manner.
In one embodiment of the present invention, the battery pack further comprises a plurality of test units, each test unit comprising a plurality of reference groups, two cells of the reference groups being denoted as a first cell and a second cell;
in the same test unit, the health degrees of the first batteries in the multiple reference groups are the same, and the health degrees of the second batteries in the multiple reference groups are in gradient change;
in different test units, the health level gradient of the first cell in the reference group varies.
In one embodiment of the present invention, the step of querying the database according to the health degree of the battery to be tested in the group to be tested and calculating the cycle life of the group to be tested according to the cycle life of the reference group includes:
inquiring a database according to the health degree of the battery to be tested in the group to be tested, wherein a reference group consistent with the health degree of the battery to be tested exists in the database, and marking the reference group as a reference service life n according to the cycle service life corresponding to the reference group;
and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter.
In one embodiment of the invention, 0.8.ltoreq.k.ltoreq.1.
In one embodiment of the present invention, the step of querying the database according to the health degree of the battery to be tested in the group to be tested and calculating the cycle life of the group to be tested according to the cycle life of the reference group includes:
traversing the database according to the health degree of the battery to be tested of the group to be tested, and obtaining the cycle life of the battery pack formed by the batteries with the health degree adjacent to the health degree of the battery to be tested, wherein the reference group consistent with the health degree of the battery to be tested does not exist in the database;
predicting the theoretical cycle life n of the group to be detected by interpolation or extrapolation;
and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter.
In one embodiment of the present invention, the method for calculating the empirical parameters is:
acquiring historical test data of a battery pack, wherein the historical test data comprises cycle life obtained by calculation of the battery pack and cycle life after actual use;
calculating to obtain a ratio K i Cycle life after actual use/cycle life calculated;
the historical test data of n battery packs are averaged to obtain an empirical parameter K= (K) 1 +K 2 +K 3 +……+K n )/n。
In one embodiment of the invention, historical test data is continuously updated during the lifetime assessment process.
In one embodiment of the present invention, during the process of charging and discharging the batteries in each reference group, when any one of the batteries reaches the discharge cut-off standard, the reference group stops discharging.
The invention discloses a battery pack life assessment system, comprising:
the testing module is used for constructing a plurality of reference groups, each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, the health degree of at least one battery among different reference groups is different, the batteries in each reference group are subjected to charge and discharge testing, the number of charge and discharge cycles of the batteries of the reference group and the capacity retention rate after each charge and discharge cycle are recorded respectively, and the cycle life of the corresponding reference group is obtained;
the database construction module is used for establishing a database, and the database comprises a plurality of groups of detection data, wherein each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group;
the detection and calculation module is used for obtaining a group to be detected, the group to be detected comprises a plurality of batteries to be detected which are connected in series, the health degree of the batteries to be detected is recorded, a database is inquired according to the health degree of the batteries to be detected of the group to be detected, and the cycle life of the group to be detected is calculated according to the cycle life of the reference group.
Compared with the prior art, the technical scheme of the invention has the following advantages:
1. the invention obtains the cycle life of the reference group by constructing the reference group, constructs a database, wherein the database comprises a plurality of groups of detection data, each group of detection data comprises the health degree of the battery in the reference group and the cycle life of the corresponding reference group, and then inquires the database according to the health degree of the battery to be detected, so that the cycle life of the battery to be detected can be calculated and obtained. The invention can more accurately and effectively predict the cycle life of the battery pack assembled by batteries with different healthiness, and reduce the experiment cost.
2. In the invention, the number of the batteries in the to-be-tested group is the same as that of the reference group, and the health degree of each battery in the to-be-tested group is set in one-to-one correspondence with that of the batteries in the reference group, so that the health degree of a battery pack formed by the batteries in the to-be-tested group can be predicted and obtained according to the test data of the reference group.
Drawings
FIG. 1 is a flow chart of a method for battery pack life assessment in accordance with the present invention;
FIG. 2 is a cycle curve of two fresh cells in series;
fig. 3 is a schematic graph of the cycle curve after two batteries of 100% soh and 97% soh are connected in series.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Referring to fig. 1, the invention discloses a battery pack life assessment method, comprising the following steps:
constructing a plurality of reference groups, wherein each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, and the health degree of at least one battery is different between different reference groups;
performing charge and discharge tests on the batteries in each reference group, and respectively recording the charge and discharge cycle number and the capacity retention rate after each charge and discharge cycle of the batteries in the reference group to obtain the cycle life of the corresponding reference group;
establishing a database, wherein the database comprises a plurality of groups of detection data, and each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group;
obtaining a to-be-tested group, wherein the to-be-tested group comprises a plurality of to-be-tested batteries connected in series, and recording the health degree of the to-be-tested batteries;
inquiring a database according to the health degree of the batteries to be tested of the group to be tested, and calculating the cycle life of the group to be tested according to the cycle life of the reference group.
The working principle of the invention is as follows: the invention obtains the cycle life of the reference group by constructing the reference group, constructs a database, wherein the database comprises a plurality of groups of detection data, each group of detection data comprises the health degree of the battery in the reference group and the cycle life of the corresponding reference group, and then inquires the database according to the health degree of the battery to be detected, so that the cycle life of the battery to be detected can be calculated and obtained. The invention can more accurately and effectively predict the cycle life of the battery pack assembled by batteries with different healthiness, and reduce the experiment cost.
The number of the batteries in the to-be-tested group is the same as that of the batteries in the reference group, and the health degree of each battery in the to-be-tested group is set in one-to-one correspondence with that of the batteries in the reference group. Thus, the health degree of the battery pack formed by the batteries in the to-be-tested group can be predicted and obtained according to the test data of the reference group.
Further, in an embodiment, the reference set and the battery in the test set are two. The two cells of the reference group are denoted as a first cell and a second cell; the health degree of the first batteries in the plurality of reference groups is the same, and the health degree of the second batteries in the plurality of reference groups is changed in a gradient manner. For example, in all reference groups, the first cell had a degree of health of 90%, while the second cell had a degree of health of 100%, 98%, 96%, 94%, … …,10%. By this arrangement, different combinations of reference groups can be obtained.
In another embodiment, the invention further comprises a plurality of test units, each test unit comprising a plurality of reference groups, two cells of the reference groups being denoted as a first cell and a second cell.
In the same test unit, the health degree of the first batteries in the plurality of reference groups is the same, and the health degree of the second batteries in the plurality of reference groups is in gradient change. For example, in the same reference group, the first cell had the same health, while the second cell had a health of 100%, 98%, 96%, 94%, … …,10%.
In different test units, the health level gradient of the first cell in the reference group varies. For example, the health of the first battery may be 100%, 98%, 96%, 94%, … …,10% in order in different test units. Therefore, the test unit can obtain various reference combinations, so that more samples are provided for the life estimation of the subsequent battery pack to be tested, and the accuracy of the subsequent life estimation is improved.
Further, according to the health degree of the battery to be tested of the group to be tested, the cycle life of the group to be tested is calculated according to the cycle life of the reference group, including:
inquiring a database according to the health degree of the battery to be tested in the group to be tested, wherein a reference group consistent with the health degree of the battery to be tested exists in the database, and marking the reference group as a reference service life n according to the cycle service life corresponding to the reference group;
and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter. Wherein k is more than or equal to 0.8 and less than or equal to 1.
Specifically, the method for calculating the cycle life of the to-be-measured group according to the cycle life of the reference group by inquiring the database according to the health degree of the to-be-measured battery of the to-be-measured group comprises the following steps:
1. traversing the database according to the health degree of the battery to be tested of the group to be tested, and obtaining the cycle life of the battery pack formed by the batteries with the health degree adjacent to the health degree of the battery to be tested, wherein the reference group consistent with the health degree of the battery to be tested does not exist in the database;
2. predicting the theoretical cycle life n of the group to be detected by interpolation or extrapolation;
3. and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter.
Further, the calculation method of the experience parameters is as follows:
acquiring historical test data of the battery pack, wherein the historical test data comprises cycle life obtained by calculation of the battery pack and cycle life after actual use;
calculating to obtain a ratio K i Cycle life after actual use/cycle life calculated;
the historical test data of n battery packs are averaged to obtain an empirical parameter K= (K) 1 +K 2 +K 3 +……+K n ) And/n. By the method, the obtained experience parameters are more accurate, so that the accuracy of the life assessment of the battery pack is improved.
In the life evaluation process, the historical test data can be continuously updated, so that the accuracy and precision of calculation are improved.
In the process of charging and discharging the batteries in each reference group, when any one of the batteries reaches the discharge cut-off standard, the reference group stops discharging.
The invention also discloses a battery pack service life assessment system, which comprises a test module, a database construction module and a detection and calculation module.
The test module is used for constructing a plurality of reference groups, each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, the health degree of at least one battery among different reference groups is different, the battery in each reference group is subjected to charge and discharge test, the number of charge and discharge cycles of the battery in the reference group and the capacity retention rate after each charge and discharge cycle are recorded respectively, and the cycle life of the corresponding reference group is obtained.
The database construction module is used for establishing a database, and the database comprises a plurality of groups of detection data, wherein each group of detection data comprises the health degree of batteries in the reference group and the cycle life of the corresponding reference group.
The detection and calculation module is used for obtaining a to-be-detected group, wherein the to-be-detected group comprises a plurality of to-be-detected batteries connected in series, the health degree of the to-be-detected batteries is recorded, a database is inquired according to the health degree of the to-be-detected batteries of the to-be-detected group, and the cycle life of the to-be-detected group is calculated according to the cycle life of the reference group.
The technical scheme of the invention is further described and explained below with reference to specific embodiments.
The influence of the series connection of the battery cells of different SOHs on the service life of the battery pack is researched, and the battery cells of different SOHs are only required to be connected in series and circulated in preset parameters such as temperature T, current I, voltage range and the like; in the cyclic charge and discharge process of the experimental small battery pack, any one cell reaches the upper limit voltage or the lower limit voltage, and the cycle can jump to the next test step. The charge and discharge are recorded as one cycle, and each cycle is performed. The discharge capacity of each circle of the small battery pack is recorded, and the capacity retention rate phi of the small battery pack after circulation is calculated, wherein the capacity retention rate phi is the ratio of the discharge capacity of each circle to the corresponding total capacity of the single battery cell (the discharge capacity of the single battery cell under the same working condition).
And (3) data processing: and (3) making a relation graph of capacity retention rate and cycle number after each cycle of the small battery pack: the number of cycles is on the abscissa and the capacity retention is on the ordinate. And obtaining the relation between the capacity retention rate of the small battery pack and the cycle number.
Meanwhile, a plurality of groups of experiments can be set, SOH among the electric cores in each group of experiments is changed in a gradient manner (for example, the small battery pack M1 is formed by connecting two fresh batteries in series, namely, SOH of a 1# battery and SOH of a 2# battery in the small battery pack M1 are both equal to 100%, SOH of a 1# battery in the small battery pack M2 is 100%, SOH of a 2# battery is 97%), the electric cores with different SOH differences are assembled into the small battery pack, and then the relation between the capacity retention rate and the cycle number in the cycle process of the different small battery packs is measured. The relationship between the capacity retention rate of the plurality of groups of small battery packs and the number of cycles can be established as a database C.
When evaluating the life of a battery pack composed of cells of different SOHs, the maximum value SOHmax and the minimum value SOHmin of the SOHs of the cells in the battery pack are measured first. If the database C has the cycle life of the small battery pack consisting of SOHmax and SOHmin, the cycle life can be directly multiplied by an empirical factor to be used as the cycle life of the battery pack. The empirical factor may be between 0.8 and 1.
If the database C has no cycle life of the small battery pack composed of two SOHs of SOHmax and SOHmin, the cycle life of the small battery pack composed of two SOHs of SOHmax, SOHmin can be predicted by interpolation or extrapolation methods by using the life of the small battery pack composed of two SOHs of SOHmax, SOHmin; this cycle life is then multiplied by an empirical factor to be the cycle life of the battery pack.
Through testing, the inventor can see from the circulation data of the real battery that televisions with different health degrees are connected in series, and the difference of circulation life is larger.
Experiment design: the small battery group M1 is formed by connecting two fresh batteries in series, namely the SOH of the 1# battery and the SOH of the 2# battery in the M1 are equal to 100%, and the circulating data are shown in figure 1; SOH of the 1# battery in the small battery M2 was 100%, SOH of the 2# battery was 97%, and the cycle data are shown in fig. 2.
Next, the battery pack life evaluation method in the present invention is further explained by calculation of two sets of experimental data.
Two sets of experimental data are shown, experimental set 1 is two cells with soh=100% and soh=100% in series, and experimental set 2 is two cells with soh=100% and soh=97% in series. If sohmax=100% and sohmin=97% in the battery pack whose lifetime is to be estimated, the cycle lifetime of the battery pack can be multiplied by an empirical factor as the cycle lifetime of the battery pack.
If sohmax=100% and sohmin=98% in the battery pack whose life is to be evaluated, the cyclic life T1 of the experimental group 1 and the cyclic life T2 of the experimental group 2 may be used to obtain the cyclic life T3 of a small battery pack in which two batteries of soh=100% and soh=98% are connected in series by interpolation, and then the cyclic life T3 is multiplied by an empirical coefficient as the cyclic life of the battery pack. Solving the formula of T3 by interpolation:
if sohmax=100% and sohmin=96% in the battery pack whose life is to be evaluated, the cyclic life T1 of the experimental group 1 and the cyclic life T2 of the experimental group 2 may be used to obtain the cyclic life T4 of a small battery pack in which two batteries of soh=100% and soh=96% are connected in series by extrapolation, and then the cyclic life T4 is multiplied by an empirical factor as the cyclic life of the battery pack. The formula for solving T4 by extrapolation:
it will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (12)
1. A battery pack life assessment method, comprising:
constructing a plurality of reference groups, wherein each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, and the health degree of at least one battery is different between different reference groups;
performing charge and discharge tests on the batteries in each reference group, and respectively recording the charge and discharge cycle number and the capacity retention rate after each charge and discharge cycle of the batteries in the reference group to obtain the cycle life of the corresponding reference group;
establishing a database, wherein the database comprises a plurality of groups of detection data, and each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group;
acquiring a to-be-tested group, wherein the to-be-tested group comprises a plurality of batteries to be tested which are connected in series, and recording the health degree of the batteries to be tested;
inquiring a database according to the health degree of the batteries to be tested of the group to be tested, and calculating the cycle life of the group to be tested according to the cycle life of the reference group.
2. The battery pack life evaluation method according to claim 1, wherein the number of batteries in the group to be measured is the same as the number of batteries in the reference group, and the health degree of each battery in the group to be measured is set in one-to-one correspondence with the health degree of the battery in the reference group.
3. The battery pack life assessment method according to claim 1, wherein the reference group and the test group are two batteries.
4. The battery pack life evaluation method according to claim 3, wherein the two batteries of the reference group are noted as a first battery and a second battery;
the health degree of the first batteries in the plurality of reference groups is the same, and the health degree of the second batteries in the plurality of reference groups is changed in a gradient manner.
5. The battery pack life assessment method according to claim 3, wherein,
the system further comprises a plurality of test units, wherein each test unit comprises a plurality of reference groups, and two batteries of the reference groups are denoted as a first battery and a second battery;
in the same test unit, the health degrees of the first batteries in the multiple reference groups are the same, and the health degrees of the second batteries in the multiple reference groups are in gradient change;
in different test units, the health level gradient of the first cell in the reference group varies.
6. The battery pack life assessment method according to claim 3, wherein the querying the database according to the health degree of the battery to be tested of the group to be tested, calculating the cycle life of the group to be tested according to the cycle life of the reference group, comprises:
inquiring a database according to the health degree of the battery to be tested in the group to be tested, wherein a reference group consistent with the health degree of the battery to be tested exists in the database, and marking the reference group as a reference service life n according to the cycle service life corresponding to the reference group;
and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter.
7. The battery pack life assessment method according to claim 6, wherein 0.8.ltoreq.k.ltoreq.1.
8. The battery pack life assessment method according to claim 3, wherein the querying the database according to the health degree of the battery to be tested of the group to be tested, calculating the cycle life of the group to be tested according to the cycle life of the reference group, comprises:
traversing the database according to the health degree of the battery to be tested of the group to be tested, and obtaining the cycle life of the battery pack formed by the batteries with the health degree adjacent to the health degree of the battery to be tested, wherein the reference group consistent with the health degree of the battery to be tested does not exist in the database;
predicting the theoretical cycle life n of the group to be detected by interpolation or extrapolation;
and calculating the cycle life of the group to be tested, wherein the cycle life m=n×k of the group to be tested, and k is an empirical parameter.
9. The battery pack life assessment method according to claim 6 or 8, wherein the empirical parameter calculation method is:
acquiring historical test data of a battery pack, wherein the historical test data comprises cycle life obtained by calculation of the battery pack and cycle life after actual use;
calculating to obtain a ratio K i Cycle life after actual use/cycle life calculated;
the historical test data of n battery packs are averaged to obtain an empirical parameter K= (K) 1 +K 2 +K 3 +……+K n )/n。
10. The battery pack life assessment method according to claim 9, wherein,
in the life evaluation process, the historical test data is continuously updated.
11. The method of evaluating the life of a battery pack according to claim 1, wherein, during the charge and discharge of the batteries in each reference group,
when any one of the batteries reaches the discharge cut-off standard, the reference group stops discharging.
12. A battery pack life assessment system, comprising:
the testing module is used for constructing a plurality of reference groups, each reference group comprises a plurality of batteries connected in series, the health degree of at least two batteries connected in series in the same reference group is different, the health degree of at least one battery among different reference groups is different, the batteries in each reference group are subjected to charge and discharge testing, the number of charge and discharge cycles of the batteries of the reference group and the capacity retention rate after each charge and discharge cycle are recorded respectively, and the cycle life of the corresponding reference group is obtained;
the database construction module is used for establishing a database, and the database comprises a plurality of groups of detection data, wherein each group of detection data comprises the health degree of batteries in a reference group and the cycle life of the corresponding reference group;
the detection and calculation module is used for obtaining a group to be detected, the group to be detected comprises a plurality of batteries to be detected which are connected in series, the health degree of the batteries to be detected is recorded, a database is inquired according to the health degree of the batteries to be detected of the group to be detected, and the cycle life of the group to be detected is calculated according to the cycle life of the reference group.
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