JP6146102B2 - Charging method for control valve type lead acid battery - Google Patents

Description

  The present invention relates to a charging method for a control valve type lead-acid battery that is used while being controlled in a partially charged state.

  It is known that when a lead-acid battery is used in a partially charged state (PSOC (Partial State of Charge)), life reduction (sulfation) due to accumulation of lead sulfate is likely to occur. Previously, accumulation of lead sulfate was remarkable in the negative electrode, but the life performance of the negative electrode was improved by taking measures such as adding carbon to the active material. For this reason, if it is a use which charges using night electric power and uses this for the peak cut of the daytime etc., the lifetime performance of a lead storage battery does not deteriorate so much. However, when used for leveling the load in conjunction with wind power generation or the like that charges and discharges almost all day under PSOC control, the lead storage battery may cause sulfation early and have a short life. In addition, a control valve type lead-acid battery is generally used for such an application for leveling the load in cooperation with wind power generation or the like.

  For this reason, for lead storage batteries used under the control of PSOC, measures are taken to periodically charge the batteries and refresh the state of the batteries (Patent Document 1). Various methods are known as the equal charge method, and the method is often performed at a constant voltage, but may be performed at a constant current.

  The advantage of uniform charging by constant voltage charging is to extend the life performance by suppressing the corrosion of the positive grid and electrolysis of the electrolyte because the charging is performed while keeping the voltage during charging low while suppressing the overcharge amount. It is possible to do. However, sufficient effects may not be achieved with respect to deterioration factors such as stratification and sulfation.

  On the other hand, even charging by constant current charging is less efficient than constant voltage charging, but it can also flow current to parts where charging current does not flow easily, so it is effective in eliminating deterioration factors such as stratification and sulfation. To do. However, if it is carried out excessively, the life performance may be shortened because the amount of positive electrode grid corrosion and the amount of decomposition of the electrolytic solution becomes larger than those of constant voltage charging.

  In addition, even if charge is performed using any of the charging methods, if the size of the battery increases, the state of charge in the electrode plate tends to vary, making it difficult to sufficiently obtain the refresh effect by the uniform charge.

JP 2003-163034 A

  Therefore, in view of the above situation, the present invention provides a charging method for a control valve type lead-acid battery capable of providing a sufficient refreshing effect and improving life performance even when a large battery is used under PSOC control. This is what I wanted.

  That is, in the charging method for the control valve type lead storage battery according to the present invention, the distance between the center point at the lower end of the electrode plate current collector and the point on the periphery of the electrode plate body farthest from the point is 20 cm or more. When the control valve type lead-acid battery with a plate is to be charged and the cumulative discharge electricity related value, which is the value related to the cumulative discharge electricity from the previous equal charge, exceeds the preset upper limit value, the next time In the uniform charge, after the constant voltage charge is performed, a uniform charge step of performing constant current charge is further provided. Here, the “cumulative discharge electric quantity related value” is not particularly limited as long as it is a value related to the cumulative discharge electric quantity. For example, in addition to the cumulative discharge electric quantity, the cumulative charge electric quantity from the previous equal charge is added. And the sum of the absolute value of the accumulated discharge electricity amount and the accumulated charge electricity amount from the previous equal charge.

  “Constant voltage charging” generally refers to a charging method performed while controlling the current so as not to exceed a predetermined voltage. Normally, when the state of charge is low, the voltage during charging is low, and the voltage increases as charging proceeds. When a certain voltage is reached, a reaction other than the charging reaction of the active material (for example, electrolysis of water) occurs, so that the charging method is performed so as not to reach a predetermined voltage.

  Moreover, the maximum output is determined for any charging device, and may be limited by the current value or the power value. Therefore, if the state of charge is so low that it does not reach a predetermined voltage, it will continue to be charged with the maximum output current or power until the voltage is reached.

  In the present invention, a detailed charging method until reaching a predetermined voltage is not stipulated, but for example, it is not practical if the maximum current is too small for the battery capacity, and immediately even if the maximum current is large. Since the voltage during charging increases, the specifications of the battery and the charging device may not be balanced.

  The maximum current of the charging device with respect to the battery capacity is within the range of current values of 0.1 CA to 3 CA regardless of whether it is limited by the current value or the power value. preferable.

  In the present invention, when the cumulative discharge electricity quantity related value is a cumulative discharge electricity quantity value, the preset upper limit value is 5 CAh.

  Moreover, what is necessary is just to determine the charge electricity amount by the said constant current charge based on the said cumulative discharge electricity amount related value, for example.

  Furthermore, the charging current during the constant current charging is preferably 0.05 CA or less.

  According to the present invention having such a configuration, even when a large-sized battery is used under PSOC control, a sufficient refresh effect can be obtained, and the life performance can be improved.

It is a schematic diagram which shows a positive electrode plate. It is a graph showing the difference in the life cycle number by the kind of battery, and the size (longest distance) of a positive electrode plate. It is a graph showing the relationship between the size (longest distance) of a positive electrode plate, and the number of life cycles. It is a graph showing the relationship between the amount of accumulated discharge electricity and the number of life cycles. It is a graph showing the relationship between the amount of charge electricity at a constant current and the number of life cycles for each cumulative discharge amount of electricity. It is a graph showing the relationship between the amount of accumulated discharge electricity and the amount of charge charged at a constant current. It is a graph showing the relationship between the charging current at the time of constant current charge, terminal voltage, and sealing reaction efficiency.

  Embodiments of the present invention will be described below.

  The charging method according to the present invention includes a positive electrode plate having a distance between a point at the center of the lower end of the electrode plate current collector (ear part) and a point on the periphery of the electrode plate body that is farthest from the point is 20 cm or more. The control valve type lead-acid battery is intended. In the valve-regulated lead-acid battery, the electrolyte is held in a separator made of fine glass or the like, or gelled, and is not fluidized, so that stratification hardly occurs. For this reason, the control valve type lead storage battery is suitably used for a load leveling in cooperation with wind power generation or the like.

  In the present invention, “the distance between the central point at the lower end of the electrode plate current collector and the point on the periphery of the electrode plate body farthest from the point is 20 cm or more” means, for example, in the form shown in FIG. In the positive electrode plate 1, the intersection P between the boundary line L between the current collector 2 and the main body 3 and the vertical center line C 1 of the current collector 2 and the intersection P across the vertical center line C 2 of the main body 3 in plan view. Means that the distance from the lower vertex Q of the main body 3 located on the opposite side is 20 cm or more. In a large electrode plate where the distance between the center of the lower end of the electrode current collector and the point on the periphery of the electrode plate body farthest from the point is 20 cm or more, the charged state in the electrode plate Since variations are likely to occur, it is difficult to obtain a refresh effect with uniform charging only by constant voltage charging.

  In the present invention, at the time of equal charge, after performing constant voltage charge, in order to determine whether or not to perform constant current charge, the accumulated discharge electricity amount is a value related to the accumulated discharge electricity amount from the previous equal charge. For the related value, a preset upper limit value is set.

  The preset upper limit value is, for example, 5 CAh when the cumulative discharge electricity quantity related value is a cumulative discharge electricity quantity value. When the cumulative amount of electricity discharged exceeds 5 CAh, the battery life performance is significantly reduced even when the uniform charge is performed only by constant voltage charging. The accumulated discharge electricity amount of 5 CAh does not include the discharge electricity amount in the regulated discharge.

  In the present invention, when the cumulative discharge electricity quantity related value exceeds a preset upper limit value, in the next equal charge, after performing constant voltage charge, constant current charge is further performed as push charge. For example, when charging a 12V battery for automobiles at a constant voltage, a voltage of 13.8 to 14.7V (2.3 to 2.45V / cell) is usually applied, but the voltage of the battery as charging progresses. Therefore, when the voltage on the charger side is set to the above voltage, there is no voltage difference from the lead storage battery to be charged, and the charging current decreases. Such a decrease in current indicates that the state of charge of the lead-acid battery is approaching 100%.

  However, the lead-acid battery has a short life even if it is charged evenly by only constant voltage charging after use in PSOC with a cumulative discharge electricity amount exceeding 5 CAh, because of the difference in charging efficiency between the positive and negative active materials It is thought that there is. In particular, when carbon is added to the active material, the charging efficiency of the positive electrode active material is lower than the charging efficiency of the negative electrode active material. Also, in constant voltage charging, the polarization of the negative electrode has a greater effect on the amount of electricity received during charging, so that the amount of charge electricity is limited by the polarization of the negative electrode while the positive electrode is not sufficiently refreshed. Conceivable. On the other hand, it is estimated that the positive electrode can also be refreshed by performing constant current charging after constant voltage charging.

  The amount of electricity charged by the constant current charging may be determined based on the cumulative discharge electricity amount related value. Here, “determining based on the accumulated discharge electricity amount related value” as to the charge electricity amount by the constant current charging means that the accumulated discharge electricity amount related value prepared in advance and the charge electricity amount by the constant current charging are used. Is determined from the function, map, table, etc. representing the corresponding relationship with the constant current charging in accordance with the cumulative discharge electricity amount related value. In addition, what is necessary is just to change charge time, for example, in order to adjust the amount of charge electricity by the said constant current charge.

  The constant current charging is preferably performed at a current of 0.05 CA or less. If the charging current during constant current charging is too large, the rate of electrolysis of the water in the electrolyte will increase, and oxygen absorption at the negative electrode will not catch up, and the battery temperature during charging will rise. It tends to cause withering. For this reason, it is appropriate to select a current with such a magnitude that the sealing reaction efficiency is 50% or more, and 0.05 CA is a suitable current that is not too large. On the other hand, if the charging current during constant current charging is too small, it is difficult to sufficiently refresh the active material, which is not preferable. For this reason, for example, it is appropriate to select a current having such a magnitude that the terminal voltage exceeds 2.5 V, and the lower limit of the charging current during constant current charging is preferably about 0.03 CA.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Production of test battery>
Control valve type lead acid batteries having the specifications shown in Table 1 below were prepared and used for the test. In Table 1 below, “longest distance” means the distance between the point at the center of the lower end of the current collector of the positive electrode plate and the point on the periphery of the main body that is farthest from the point. As shown in FIG. 1, in plan view, the intersection P between the boundary line L between the current collector 2 and the main body 3 and the vertical center line C1 of the current collector 2 and the vertical center line C2 of the main body 3 are sandwiched. It means the distance between the lower vertex Q of the main body 3 located on the opposite side of the intersection P.

<Cycle life test (1)>
A cycle life test (1) was performed on the produced test battery according to the conditions shown in Table 2 below. Specifically, first, adjusted discharge was performed, and then discharging and charging were repeated, and uniform charging was performed at a constant voltage every 10 cycles (accumulated electric discharge amount 2 CAh).

Then, a capacity test is performed every 500 cycles according to the following conditions, and when the time to reach the final voltage falls below 7 hours (corresponding to 70% of the rated capacity), the number of cycles at that time is the number of life cycles. It was. The results are shown in FIGS.
(1) Discharge: 0.1 CA, final voltage 1.8V
(2) Charging; conforms to uniform charging

<Cycle life test (2)>
A cycle life test (2) was performed using a D-type test battery and changing the conditions for equal charge. In the cycle life test (2), adjusted discharge, discharge and charge were performed in the same manner as the cycle life test (1), while equal charge was performed according to the conditions shown in Table 3 below. Then, a capacity test was performed in the same manner as the cycle life test (1) every 500 cycles to determine the battery life. The results are shown in Table 3 and FIGS. Among these, FIG. 1 to 3 are graphs showing the relationship between the cumulative amount of discharged electricity and the number of life cycles when uniform charging is performed only by constant voltage charging for comparison, and FIG. FIG. 6 is a graph showing the relationship between the amount of charge electricity at a constant current and the number of life cycles for each cumulative discharge electricity amount (10, 20, 30 CAh) for comparison with 3 to 20, and FIG. FIG. 5 is a graph showing the relationship between the amount of charge electricity at a constant current when the accumulated discharge electricity amount has a long life.

  In FIG. 6, the case where the life is long means the case where the number of life cycles is the highest for each cumulative discharge electricity amount, and the life cycle number is 11000 when the amount of accumulated discharge electricity is 10 CAh. In the case (Battery No. 5 and 6), when the cumulative discharge electricity amount is 20 CAh, the life cycle number is 10,000 (Battery No. 11 to 13), and when the cumulative discharge electricity amount is 30 CAh, the life is reached. This is the case where the number of cycles is 9500 (batteries No. 18 and 19).

<Evaluation of charging current during constant current charging>
The batteries in a fully charged state were subjected to constant current charging from the smaller current under the conditions shown in Table 4 below, and the terminal voltage and the sealed reaction efficiency immediately before the end of energization were measured.

The measurement of the sealing reaction efficiency was performed according to the method of JIS C 8972 except for the energizing current, energizing time and gas sampling time shown in Table 4, but the calculation formula for the sealing reaction efficiency was slightly modified as follows. The formula with was used.
Sealing reaction efficiency η = (1−ν / 684) × gas sampling duration (min) / 60
The measurement results of terminal voltage and sealing reaction efficiency are shown in Table 5 and FIG.

<Result>
As shown in the graphs of FIGS. 2 and 3, the longer the maximum distance, the smaller the number of life cycles. Further, as can be seen from the graph of FIG. 2, this tendency was not affected by the number of electrode plates.

  Further, as shown in the graph of FIG. 4, it has been found that when the cumulative amount of discharged electricity exceeds 5 CAh, the cycle life performance deteriorates if only constant voltage charging is performed during equal charge. Furthermore, as can be seen from the graphs of FIGS. 5 and 6, the preferred range of charge electricity at a constant current differs depending on the accumulated discharge electricity. The graph represented by the solid line in FIG. 6 is a graph that connects the centers of the range of charge electricity with a long life for each accumulated discharge electricity, and charging at constant current charging based on the accumulated discharge electricity. When determining the amount of electricity, for example, the amount of charge may be determined according to a graph represented by a solid line in FIG.

  Further, as shown in the graph of FIG. 7, when the charging current during constant current charging is 0.05 CA, the terminal voltage exceeds 2.5 V at which the active material can be sufficiently refreshed, and a high hermeticity is achieved. The reaction efficiency was shown. On the other hand, if the charging current during constant current charging is too small, the terminal voltage may be less than 2.4V. On the other hand, if the charging current is too large, the hermetic reaction efficiency is drastically reduced, resulting in early liquid drainage. Therefore, about 0.05 CA is preferable.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode plate 2 ... Current collection part 3 ... Main body

Claims (4)

A control valve type that includes a positive electrode plate having a distance between a point at the center of the lower end of the electrode plate current collector and a point on the periphery of the electrode plate body that is farthest from the point, and is controlled in a partially charged state Apart from charging in the control in the partially charged state for the lead storage battery , it performs equal charging,
If the cumulative discharge electricity quantity related value, which is a value related to the cumulative discharge electricity quantity from the previous equal charge, is less than or equal to the preset upper limit value, only the constant voltage charge is performed in the next equal charge, and the cumulative discharge is performed. When the electric quantity related value exceeds the upper limit value, in the next equal charge, the constant voltage charge is performed after the constant voltage charge, and the charging method for the control valve type lead storage battery is characterized by the following. The cumulative discharge electricity quantity related value is a cumulative discharge electricity quantity value,
The method for charging a control valve type lead storage battery according to claim 1, wherein the preset upper limit value is 5 CAh.   The charging method for a control valve type lead storage battery according to claim 1 or 2, wherein the charge electricity amount by the constant current charge is determined based on the cumulative discharge electricity amount related value. The charging method for the control valve type lead-acid battery according to claim 1, 2 or 3, wherein a charging current during the constant current charging is 0.05 CA or less.