CN102608540B - Coulomb efficiency measuring method used for SOC (system-on-chip) evaluation of power battery - Google Patents

Abstract

The invention discloses a coulomb efficiency measuring method used for SOC (system-on-chip) evaluation of a power battery, relates to the technical field of power batteries or power battery pack management and aims at solving the problems that in the prior art, when the coulomb efficiency is calculated, the capacitance range of the battery in the practical use is not considered, and the coulomb efficiency is not accurate caused by the self temperature change of the battery in charging and discharging process and the like. The method comprises the following specific steps: conducting HPPC (hybrid pulse-power capability) test on a battery to be detected, and recording a voltage time curve and a current time curve in the HPPC test; calculating the relation curve of pulse power capacity and charging electric quantity according to the obtained voltage time curve and current time curve, and calculating the minimum discharging depth and the maximum discharging depth according to the curve; calculating the coulomb efficiency of middle discharging depth; charging the battery to the middle discharging depth, charging for n times to keep the work condition, discharging the battery completely, and calculating the coulomb efficiency of the battery to be detected. The method disclosed by the invention is used for measuring the coulomb efficiency of batteries in the fields of electric automobiles, renewable energy sources, and large-scale energy storage.

Description

A kind of coulomb efficiency test method of estimating for electrokinetic cell SOC

Technical field

The present invention is a kind of coulomb efficiency test method of estimating for electrokinetic cell SOC, relates to electrokinetic cell or power battery group management technical field.

Background technology

At present, the protection of people's pay attention to day by day to environment and the use effectively and reasonably of the energy.Therefore, new-energy automobiles efficient, energy-saving and environmental protection just become the development trend of automobile industry.In order to ensure the execution of electrokinetic cell safety and integrated vehicle control tactics, the research and development of power battery management system are particularly important.Wherein SOC (dump energy number percent) is as the topmost influence factor of battery behavior, is one of the focus of batteries management system research in recent years and difficult point.

Ah counting method is the battery SOC method of estimation that current electric automobile the most often uses, and its principle is that the integration by load current is estimated SOC, is simple and easy to, algorithm stablely, and formula is as follows:

$\mathrm{SOC}={\mathrm{SOC}}_0-\frac{1}{C_A}{\∫}_{t_0}^t\mathrm{\ηIdt}$

SOC in formula ₀for preliminary examination SOC, C _afor battery active volume, η is a coulomb efficiency.Can find out that by above formula the accurate calculating of coulomb efficiency directly affects the computational accuracy of ampere-hour method.

Due to the existence of internal resistance, the loss that any charging of battery, discharge process have electric weight, in the time estimating the SOC of battery, must consider a coulomb efficiency.United States advanced battery federation (USABC) defines coulomb efficiency in its " electric automobile battery test handbook ": use discharge current I _dthe electric weight Q emitting from battery _dwith use charging current I _cmake battery SOC return to the front needed electric weight Q of state of electric discharge _cratio.Also have document to propose the concept of conversion coulomb efficiency, battery time-dependent current charge and discharge process is normalized to constant current charge-discharge process by it, and core concept is by the coulomb efficiency unification to 3 of different electric currents hour multiplying power discharging electric current C ₃in/3 coulomb efficiency.But the coulomb efficiency calculating by above definition is not all considered the range of capacity of battery in the time that reality is used, battery temperature of self in charge and discharge process can change and cause a coulomb efficiency change, thereby the accuracy of impact coulomb efficiency, causes SOC to estimate inaccurate.

Summary of the invention

The object of the invention is when prior art is calculated coulomb efficiency, not consider the range of capacity of battery in the time that reality is used in order to solve, battery temperature of self in charge and discharge process can change and cause a coulomb efficiency change, thereby the accuracy of impact coulomb efficiency, cause SOC to estimate inaccurate problem, the present invention realizes by following steps:

Step 1: select temperature in a certain electrokinetic cell operating temperature range to be measured as treating testing temperature, following steps two to step 7 is all carried out under this temperature conditions to be measured;

Step 2: battery to be detected is carried out to the test of combined power pulse characteristic, record volt-time curve and current-time curvel in the test of combined power pulse characteristic, calculate corresponding charge pulse power ability and discharge pulse power capability and obtain charge pulse power ability and the relation curve of charge capacity and the relation curve of discharge pulse power capability and charge capacity, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and charge capacity is minimum depth of discharge, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and discharge electricity amount is maximum depth of discharge,

Step 3: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to minimum depth of discharge, the electric weight being filled with is Q _minDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _minDOD-dis, the electric weight being filled with according to minimum depth of discharge and the electric weight of emitting calculate the average coulomb efficiency eta of minimum discharge power _minDOD, computing formula is

${\mathrm{\η}}_{\mathrm{MinDOD}}=\frac{Q_{\mathrm{MinDOD}-\mathrm{dis}}}{Q_{\mathrm{MinDOD}-\mathrm{cha}}}100\%;$

Step 4: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to maximum depth of discharge, the electric weight being filled with is Q _maxDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _maxDOD-dis, the electric weight that is filled with and emits according to maximum depth of discharge calculates the average coulomb efficiency eta of maximum discharge power _maxDOD, computing formula is: ${\mathrm{\&eta;}}_{\mathrm{MaxDOD}}=\frac{Q_{\mathrm{MaxDOD}-\mathrm{dis}}}{Q_{\mathrm{MaxDOD}-\mathrm{<figure-callout\; id="100"\; label="cha"\; filenames="HDA0000150549540000022.png,HDA0000150549540000031.png"\; state="\{\{state\}\}">cha</figure-callout>}}}100\%;$

Step 5: the mean value of the charge capacity of minimum depth of discharge and maximum depth of discharge is middle depth of discharge, depth of discharge coulomb efficiency estimated value η in the middle of the average coulomb efficiency calculation of the average coulomb efficiency of the minimum discharge power calculating respectively according to step 3 and step 4 and maximum discharge power goes out _midDOD, computing formula is

Step 6: with the constant current that is no more than safety current, battery is charged to middle depth of discharge, the electric weight being filled with is Q _midDOD-cha, static one hour, do n charging and keep operating mode, wherein 10<n<1000, the total charge volume that calculates n charging maintenance operating mode is Q _{power-sustain-cha}with total discharge capacity be Q _{power-sustain-dis}, static one hour, by battery emptying, calculate the electric weight Q emitting with the constant current that is no more than safety current _midDOD-dis;

Step 7: to step 6, calculate the coulomb efficiency eta of battery in actual usable range according to step 3, computing formula is:

$\mathrm{\&eta;}=(1-\frac{{\mathrm{\&eta;}}_{\mathrm{MidDOD}}\&times;Q_{\mathrm{MidDOD}-\mathrm{cha}}-Q_{\mathrm{MidDOD}-\mathrm{dis}}}{Q_{\mathrm{Power}-\mathrm{sustain}-\mathrm{cha}}})\&times;100\%;$

N the charging of doing described in above-mentioned steps six keeps the process of operating mode to be: bleed off certain electric weight by electric discharge, be filled with again the electric weight of equivalent, repeat to be n time with identical operating mode, keep operating mode to measure respectively before and after open-circuit voltage n charging, determine that according to the variable quantity of open-circuit voltage n charging keeps the rate of change of electric weight after operating mode, exceed 5% as n charging keeps the rate of change of electric weight after operating mode, reducing that electric weight that n charging keep bleeding off in each operating mode in operating mode re-starts step 6 until after the maintenance operating mode of charging for n time the rate of change of electric weight be less than 5%.

The present invention utilizes the charging of battery in specific usable range to keep operating mode to calculate the coulomb efficiency of battery, reach the coulomb efficiency of calculating battery in actual use, utilize when battery operated ampere-hour method estimation SOC that data are accurately provided, guarantee battery accurate estimation SOC in the process of real vehicle operation

The beneficial effect of the method is:

One, considered battery applied scope in the time of the actual use of new forms of energy car, guaranteed that the coulomb efficiency calculating meets real vehicle request for utilization.

Two, the method utilizes the charging of battery in specific usable range to keep operating mode to calculate the coulomb efficiency of battery, and therefore the method computing velocity is fast, simple, easily operation.

Three, the method has been considered the service condition of battery under condition of different temperatures, therefore has wider temperature applicable range.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of measuring electrokinetic cell coulomb efficiency; Fig. 2 is volt-time curve and the current-time curvel of combined power pulse characteristic test in embodiment two; Fig. 3 is the relation curve of pulse power ability and battery electric quantity in embodiment two; Fig. 4 is the powertrace that in embodiment two, charging keeps operating mode; Fig. 5 is volt-time curve and the current-time curvel of step 6 in embodiment two; Fig. 6 is volt-time curve and the current-time curvel that in Fig. 5,100 chargings keep operating mode.

Embodiment

Below in conjunction with Fig. 1 to Fig. 6, the specific embodiment of the present invention is described;

Embodiment one: as shown in Figure 1, the efficiency test of electrokinetic cell coulomb is undertaken by following steps:

Step 1: select a certain operating temperature range for the electrokinetic cell to be measured of-20 ℃-60 ℃, select temperature in this temperature range as treating testing temperature, following steps two to step 7 is all carried out under temperature conditions to be measured;

Step 2: battery to be detected is carried out to the test of combined power pulse characteristic, by battery emptying electricity to be detected, static one hour, take the constant current that is no more than safety current by battery charge capacity the m as available battery charge ₁%, then carries out pulse power test, static one hour, then by battery the m take the constant-current charge that is no more than safety current to electric weight as available battery charge ₂%, carries out the test of combined power pulse characteristic, and so circulation, until the m that charge capacity is available battery charge _a%, wherein: m ₁<m ₂<m _a, 0<m ₁<15,85<m _a<100,5<a<50, finishes the test of combined power pulse characteristic.Record volt-time curve and current-time curvel in the test of combined power pulse characteristic, calculate corresponding charge pulse power ability and discharge pulse power capability and obtain charge pulse power ability and the relation curve of charge capacity and the relation curve of discharge pulse power capability and charge capacity, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and charge capacity is minimum depth of discharge, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and discharge electricity amount is maximum depth of discharge,

Step 3: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to minimum depth of discharge, the electric weight being filled with is Q _minDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _minDOD-dis, the electric weight being filled with according to minimum depth of discharge and the electric weight of emitting calculate the average coulomb efficiency eta of minimum discharge power _minDOD, computing formula is

${\mathrm{\&eta;}}_{\mathrm{MinDOD}}=\frac{Q_{\mathrm{MinDOD}-\mathrm{dis}}}{Q_{\mathrm{MinDOD}-\mathrm{cha}}}100\%;$

Step 4: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to maximum depth of discharge, the electric weight being filled with is Q _maxDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _maxDOD-dis, the electric weight that is filled with and emits according to maximum depth of discharge calculates the average coulomb efficiency eta of maximum discharge power _midDOD, computing formula is: ${\mathrm{\&eta;}}_{\mathrm{MaxDOD}}=\frac{Q_{\mathrm{MaxDOD}-\mathrm{dis}}}{Q_{\mathrm{MaxDOD}-\mathrm{cha}}}\&times;100\%;$

Step 5: the mean value of the charge capacity of minimum depth of discharge and maximum depth of discharge is middle depth of discharge, depth of discharge coulomb efficiency estimated value η in the middle of the average coulomb efficiency calculation of the average coulomb efficiency of the minimum discharge power calculating respectively according to step 3 and step 4 and maximum discharge power goes out _midDOD, computing formula is

Step 6: with the constant current that is no more than safety current, battery is charged to middle depth of discharge, the electric weight being filled with is Q _midDOD-cha, static one hour, do n charging and keep operating mode, wherein 10<n<1000, the total charge volume that calculates n charging maintenance operating mode is Q _{power-sustain-cha}with total discharge capacity be Q _{power-sustain-dis}, static one hour, by battery emptying, calculate the electric weight Q emitting with the constant current that is no more than safety current _midDOD-dis, if the rate of change of electric weight exceedes 5% after 100 charging maintenance operating modes, can cause coulomb efficiency test result to produce larger error, for guaranteeing the accuracy of test result, controlling n charging keeps the rate of change of electric weight after operating mode to be no more than 5%, can be by measuring the variable quantity of open-circuit voltage, realize and controlling according to the variable quantity of open-circuit voltage, being specially n charging keeps operating mode to measure respectively before and after open-circuit voltage, determine that according to the variable quantity of open-circuit voltage n charging keeps the rate of change of electric weight after operating mode, as the rate of change of electric weight after n charging maintenance operating mode exceedes 5%, reducing that electric weight that n charging keep bleeding off in each operating mode in operating mode re-starts this step until after n charging maintenance operating mode the rate of change of electric weight be less than 5%,

Step 7: to step 6, calculate the coulomb efficiency eta of battery in actual usable range according to step 3, computing formula is:

$\mathrm{\&eta;}=(1-\frac{{\mathrm{\&eta;}}_{\mathrm{MidDOD}}\&times;Q_{\mathrm{MidDOD}-\mathrm{cha}}-Q_{\mathrm{MidDOD}-\mathrm{dis}}}{Q_{\mathrm{Power}-\mathrm{sustain}-\mathrm{cha}}})\&times;100\%.$

Embodiment two: the electrokinetic cell to be measured to embodiment one carries out a coulomb efficiency test, and determination step and result are as follows:

Step 1: select 20 ℃ of temperature in electrokinetic cell operating temperature range to be measured as temperature measuring coulomb efficiency to be measured;

Step 2: battery to be detected is carried out to the test of combined power pulse characteristic, by battery emptying electricity to be detected, static one hour, take the constant current that is no more than safety current by battery charge capacity as 10% of available battery charge, then carry out pulse power test, static one hour, again by battery take the constant-current charge that is no more than safety current to electric weight as available battery charge 20%, carry out the test of combined power pulse characteristic, so circulation, until charge capacity is available battery charge 90%, finish the test of combined power pulse characteristic.Record volt-time curve and current-time curvel in the test of combined power pulse characteristic, Fig. 2 is this curve.Calculate corresponding charge pulse power ability and discharge pulse power capability and obtain charge pulse power ability and the relation curve of charge capacity and the relation curve of discharge pulse power capability and charge capacity, computing formula is:

Cap _Discharge=V _Min·(OCV _dis-V _Min)÷R _discharge;

Cap _Regen=V _Max·(V _Max-OCV _regen)÷R _regen

Wherein: Cap _dischargefor discharge pulse power capability, Cap _regenfor charge pulse power ability, V _minfor the minimum voltage in discharge pulse process, V _maxfor the ceiling voltage in charging pulse process, OCV _disfor electric discharge open-circuit voltage, OCV _regenfor charging open-circuit voltage, $R_{\mathrm{disch}\arg e}=\frac{{\mathrm{\&Delta;V}}_{\mathrm{disch}\arg e}}{{\mathrm{\&Delta;I}}_{\mathrm{disch}\arg e}}$ For electric discharge internal resistance, $R_{\mathrm{regen}}=\frac{{\mathrm{\&Delta;V}}_{\mathrm{regen}}}{{\mathrm{\&Delta;I}}_{\mathrm{regen}}}$ For charging internal resistance.

As shown in Figure 3, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and charge capacity is minimum depth of discharge, and the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and discharge electricity amount is maximum depth of discharge; The minimum depth of discharge of determining is 40%, and the maximum depth of discharge of determining is 80%.

Step 3: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to minimum depth of discharge, the electric weight being filled with is Q _minDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _minDOD-dis, the electric weight being filled with according to minimum depth of discharge and the electric weight of emitting calculate the average coulomb efficiency eta of minimum discharge power _minDOD, computing formula is

${\mathrm{\&eta;}}_{\mathrm{MinDOD}}=\frac{Q_{\mathrm{MinDOD}-\mathrm{dis}}}{Q_{\mathrm{MinDOD}-\mathrm{cha}}}100\%;$

Step 4: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to maximum depth of discharge, the electric weight being filled with is Q _maxDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _maxDOD-dis, the electric weight that is filled with and emits according to maximum depth of discharge calculates the average coulomb efficiency eta of maximum discharge power _midDOD, computing formula is: ${\mathrm{\&eta;}}_{\mathrm{MaxDOD}}=\frac{Q_{\mathrm{MaxDOD}-\mathrm{dis}}}{Q_{\mathrm{MaxDOD}-\mathrm{cha}}}\&times;100\%;$

Step 5: the mean value of the charge capacity of minimum depth of discharge and maximum depth of discharge is middle depth of discharge, depth of discharge coulomb efficiency estimated value η in the middle of the average coulomb efficiency calculation of the average coulomb efficiency of the minimum discharge power calculating respectively according to step 3 and step 4 and maximum discharge power goes out _midDOD, computing formula is

Step 6: with the constant current that is no more than safety current, battery is charged to middle depth of discharge, calculates the electric weight Q being filled with _midDOD-cha, static one hour, bleed off certain electric weight, then be filled with the electric weight of equivalent, repeat 100 times with identical operating mode, do 100 chargings and keep operating mode, the total charge volume that calculates 100 charging maintenance operating modes is Q _{power-sustain-cha}, total discharge capacity is Q _{power-sustain-dis}, the powertrace of each charging maintenance operating mode as shown in Figure 4, is determined and is discharged and recharged power according to the parameter of battery.With 3kW power discharge 30 seconds, again with 15kW power discharge 3 seconds, then with 3.2kW power charging 55 seconds, finally with 10kW power charging 2 seconds, the volt-time curve of whole process and current-time curvel are as shown in Figure 5, Figure 6, static one hour, by battery emptying, calculate the electric weight Q emitting with the constant current that is no more than safety current _midDOD-dis;

Step 7: to step 6, calculate the coulomb efficiency eta of battery in actual usable range according to step 3, computing formula is:

$\mathrm{\&eta;}=(1-\frac{{\mathrm{\&eta;}}_{\mathrm{MidDOD}}\&times;Q_{\mathrm{MidDOD}-\mathrm{cha}}-Q_{\mathrm{MidDOD}-\mathrm{dis}}}{Q_{\mathrm{Power}-\mathrm{sustain}-\mathrm{cha}}})\&times;100\%.$

Embodiment three:

To the electrokinetic cell to be measured in embodiment two, in step 1, select 30 ℃ of temperature in electrokinetic cell operating temperature range to be measured as temperature measuring coulomb efficiency to be measured, n=15 in step 6, other step and embodiment two same measured coulomb efficiency.

Embodiment four:

To the electrokinetic cell to be measured in embodiment two, in step 1, select 40 ℃ of temperature in electrokinetic cell operating temperature range to be measured as temperature measuring coulomb efficiency to be measured, n=950 in step 6, other step and embodiment two same measured coulomb efficiency.

Through the mensuration of embodiment two, three, four, the coulomb efficiency value of this electrokinetic cell under 20 ℃, 30 ℃ and 40 ℃ of environment temperatures as shown in Table 1.

Coulomb efficiency value under 20 ℃, 30 ℃, table one and 40 ℃ of environment temperatures

Claims (4)

1. a coulomb efficiency test method of estimating for electrokinetic cell SOC, is characterized in that the method comprises the following steps:

Step 1: select temperature in a certain electrokinetic cell operating temperature range to be measured as treating testing temperature, following steps two to step 7 is all carried out under this temperature conditions to be measured;

Step 2: battery to be detected is carried out to the test of combined power pulse characteristic, record volt-time curve and current-time curvel in the test of combined power pulse characteristic, calculate corresponding charge pulse power ability and discharge pulse power capability and obtain charge pulse power ability and the relation curve of charge capacity and the relation curve of discharge pulse power capability and charge capacity, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and charge capacity is minimum depth of discharge, the charge capacity of the corresponding point of the minimal power values that meets car load power demand on the relation curve of charge pulse power ability and discharge electricity amount is maximum depth of discharge,

Step 3: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to minimum depth of discharge, the electric weight being filled with is Q _minDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _minDOD-dis, the electric weight being filled with according to minimum depth of discharge and the electric weight of emitting calculate the average coulomb efficiency eta of minimum discharge power _minDOD, computing formula is

${\mathrm{\&eta;}}_{\mathrm{MinDOD}}=\frac{Q_{\mathrm{MinDOD}-\mathrm{dis}}}{Q_{\mathrm{MinDOD}-\mathrm{cha}}}100\%;$

Step 4: by battery emptying to be detected, with the constant current that is no more than safety current, battery is charged to maximum depth of discharge, the electric weight being filled with is Q _maxDOD-cha, static one hour, then with the constant current that is no more than safety current by battery emptying, calculate the electric weight Q emitting _maxDOD-dis, the electric weight that is filled with and emits according to maximum depth of discharge calculates the average coulomb efficiency eta of maximum discharge power _maxDOD, computing formula is: ${\mathrm{\&eta;}}_{\mathrm{MaxDOD}}=\frac{Q_{\mathrm{MaxDOD}-\mathrm{dis}}}{Q_{\mathrm{MaxDOD}-\mathrm{cha}}}\&times;100\%;$

Step 5: the mean value of the charge capacity of minimum depth of discharge and maximum depth of discharge is middle depth of discharge, depth of discharge coulomb efficiency estimated value η in the middle of the average coulomb efficiency calculation of the average coulomb efficiency of the minimum discharge power calculating respectively according to step 3 and step 4 and maximum discharge power goes out _midDOD, computing formula is

Step 6: with the constant current that is no more than safety current, battery is charged to middle depth of discharge, the electric weight being filled with is Q _midDOD-cha, static one hour, do n charging and keep operating mode, wherein 10<n<1000, the total charge volume that calculates n charging maintenance operating mode is Q _{power-sustain-cha}with total discharge capacity be Q _{power-sustain-dis}, static one hour, by battery emptying, calculate the electric weight Q emitting with the constant current that is no more than safety current _midDOD-dis;

Step 7: to step 6, calculate the coulomb efficiency eta of battery in actual usable range according to step 3, computing formula is:

$\mathrm{\&eta;}=(1-\frac{{\mathrm{\&eta;}}_{\mathrm{MidDOD}}\&times;Q_{\mathrm{MidDOD}-\mathrm{cha}}-Q_{\mathrm{MidDOD}-\mathrm{dis}}}{Q_{\mathrm{Power}-\mathrm{sustain}-\mathrm{cha}}})\&times;100\%;$

N the charging of doing described in above-mentioned steps six keeps the process of operating mode to be: bleed off certain electric weight by electric discharge, be filled with again the electric weight of equivalent, repeat to be n time with identical operating mode, keep operating mode to measure respectively before and after open-circuit voltage n charging, determine that according to the variable quantity of open-circuit voltage n charging keeps the rate of change of electric weight after operating mode, exceed 5% as n charging keeps the rate of change of electric weight after operating mode, reducing that electric weight that n charging keep bleeding off in each operating mode in operating mode re-starts step 6 until after the maintenance operating mode of charging for n time the rate of change of electric weight be less than 5%.

2. the coulomb efficiency test method of estimating for electrokinetic cell SOC as claimed in claim 1, is characterized in that treating that testing temperature is 20 ℃, 30 ℃ or 40 ℃ in step 1.

3. the coulomb efficiency test method of estimating for electrokinetic cell SOC as claimed in claim 1, it is characterized in that in step 2 that the test process that battery to be detected is carried out to the test of combined power pulse characteristic is: by battery emptying electricity to be detected, static one hour, take the constant current that is no more than safety current by battery charge capacity the m as available battery charge ₁%, then carries out pulse power test, static one hour, then by battery the m take the constant-current charge that is no more than safety current to electric weight as available battery charge ₂%, carries out the test of combined power pulse characteristic, and so circulation, until the m that charge capacity is available battery charge _a%, wherein: m ₁<m ₂<m _a, 0<m ₁<15,85<m _a<100,5<a<50, finishes the test of combined power pulse characteristic.

4. the coulomb efficiency test method of estimating for electrokinetic cell SOC as claimed in claim 1, is characterized in that n=100 in step 6.

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