JP2003346913A - Control method for lead storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for a lead storage battery using the lead storage battery in a partial charged state and controlling the charged state thereof by integrating charging/discharging currents capable of adequately charging the lead storage battery, reducing the shifts of the charged states from a predetermined charged partial state caused by repeating charging/ discharging and achieving an excellent life characteristics. <P>SOLUTION: The control method for the lead storage battery using the lead storage battery in a partial charged state and controlling the charged state thereof by integrating charging/discharging currents comprises the steps of setting a charging voltage used in the partial charged state to 0.18 V/cell or more and 0.68 V/cell or less in relation to an open circuit voltage of the lead storage battery, and performing recovery charging periodically. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling a lead storage battery.

[0002]

2. Description of the Related Art A lead-acid battery for automobiles, which is mainly used for starting an engine, is always charged by a constant-voltage charging method while the engine is rotating during traveling, and the state of charge (SOC: State of charge) of the storage battery. Charge, hereinafter S
OC) is controlled to almost 100%.

On the other hand, in recent years, a system for regeneratively charging a storage battery using kinetic energy of a vehicle as electric power during deceleration has been proposed for the purpose of improving the fuel efficiency of the vehicle. In order to perform such regenerative charging, the SOC of the storage battery is set to a partially charged state (PSOC: Partial Stat) of less than 100%.
e of Charge (hereinafter, referred to as PSOC).

Further, in order to reduce the exhaust gas of the automobile, in addition to driving the engine, an electric motor assists during acceleration or stops idling when the vehicle stops,
At the start, hybrid vehicles in which an engine is driven by a lead storage battery are being used. In such a usage, it has been found that the discharge frequency is higher than in the case of only driving the engine, and in this case, the life characteristics are more excellent when the SOC is used than when the SOC is constantly maintained at 100%.

[0005] When a lead-acid battery is used in such a PSOC, the charging conditions generally applied to lead-acid batteries for automobiles cannot be said to be appropriate, and it is necessary to clarify the charging conditions.

[0006]

The object of the present invention is to provide a PS
In a control method in which a lead-acid battery is used in the OC and the SOC is managed by integrating the charge / discharge current values, a deviation from a predetermined PSOC when charging and discharging / charging suitable for the lead-acid battery are repeated is performed. It is an object of the present invention to provide a method for controlling a lead storage battery, which can reduce the load and obtain excellent life characteristics.

[0007]

SUMMARY OF THE INVENTION The inventor of the present invention has conducted tests in which various charge conditions are applied to a lead-acid battery used in a partially charged state (PSOC), and found a charge condition range suitable for the above use conditions. Was. The present invention is based on the finding, and according to claim 1, a lead-acid battery is used in PSOC,
In a control method for managing the state of charge (SOC) by integrating charge / discharge current values, the charge voltage when used in the PSOC is set to 0.
The voltage is 18 V / cell or more and 0.68 V / cell or less.

[0008] When a lead storage battery is used in a state where the SOC is 90%, for example, the SOC is managed by integrating the charge / discharge current values. Depending on the charging conditions, the charge / discharge is repeated depending on the charging conditions. In some cases, the SOC greatly decreases from 90% in a short period of time. 0.18 V with respect to the open circuit voltage of the lead storage battery of the present invention
It was found that if charging was performed at a charging voltage in the range of not less than / cell and not more than 0.68 V / cell, the SOC did not greatly deviate from the SOC, for example, 90% in a short period of time.

In constant voltage charging, the charging current is determined by the difference between the voltage of the lead storage battery and the set voltage of the charger. Therefore, when charging is performed at a voltage lower than 0.18 V / cell with respect to the open circuit voltage, the charging is performed. In the state where it is not enough, the set voltage of the charger and the voltage of the lead storage battery become the same, the charging current drops significantly,
It becomes a small current. When charging with a small current, the self-discharge of the lead storage battery and the charging are offset, and the charging efficiency is extremely poor despite the current flowing, and as a result, the charged state cannot be maintained, It is considered that the capacity decreases. On the other hand, when charging is performed at a constant voltage of 0.68 V / cell or more with respect to the open circuit voltage, gas generation, which is a side reaction during charging, becomes more remarkable at this voltage when the charged amount approaches 90%. When such charge / discharge is repeated, it is considered that the adhesion between the positive electrode active material and the grid is reduced, and the capacity is reduced. Therefore,
0.18 V / cell or more with respect to the open circuit voltage of the lead storage battery,
It is preferable to perform charging at a charging voltage in the range of 0.68 V / cell or less.

According to the second aspect, the partial charge state (P
In the control of the SOC, the recovery charge is periodically performed.

According to the first aspect of the present invention, the battery is charged at a charging voltage in a range of 0.18 V / cell or more and 0.68 V / cell or less with respect to the open circuit voltage of the lead storage battery, and the SOC is controlled by a charge / discharge current value. In this case, there is no significant decrease in the SOC from the predetermined SOC in a short period of time. However, the charging method cannot detect the charging efficiency. The decline is inevitable. Therefore, every time a fixed period elapses, the charging voltage is set to 0.68 V / cell or less with respect to the open circuit voltage, and is charged at a higher voltage, that is, a voltage in the range of 0.37 to 0.68 V / cell. Can be corrected, and stable life characteristics can be obtained. The charging in this case is defined as recovery charging.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In recent years, a system for regenerating a storage battery using kinetic energy of a vehicle at the time of deceleration for the purpose of improving fuel efficiency of a vehicle, and an electric motor for accelerating the vehicle in addition to driving an engine for the purpose of reducing vehicle exhaust gas. A hybrid vehicle that assists with a motor or stops idling when the vehicle stops and drives the engine with a lead-acid battery at the start has been used. Under such usage conditions, the SOC is constantly increased to 100%.
It has been found that using the PSOC has better life characteristics than maintaining the same. Therefore, the control method of the present invention is suitably applied to a lead storage battery for an automobile,
In the embodiment, a specific description will be given based on the result of a test performed on the assumption of the above.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a control method in which a lead storage battery is used in a PSOC and the SOC is managed by integrating charge / discharge current values, the charging voltage is set to 0.18 V / cell or more with respect to the open circuit voltage of the lead storage battery. The following tests were performed to clarify that the test was properly performed at 0.68 V / cell or less.

[0014]

[Embodiment 1] Ten lead-acid batteries for liquid type vehicles having a rated capacity of 28 Ah, a nominal voltage of 12 V, and 5.6 A were first prepared.
2.8 Ah was discharged at (0.2 CA) (C: rated capacity, A: unit of current), and the remaining capacity of the storage battery was 25.2 Ah.
Was set to SOC, 90%. The open circuit power of the storage battery at this time was 12.7V.

Here, the rated capacity refers to a capacity indicated on a storage battery or specified by a model according to a standard such as JIS, and is usually represented by Ah.

Next, these storage batteries are used for 100 cycles,
Charging and discharging were performed at various charging voltages shown in Table 1. The charge / discharge conditions are as follows.

Discharge: Charging at a current of 5.6 A for 100 minutes: Charging voltage: Maximum charging current of each charging voltage shown in Table 1: 80 A Charge: Charge the same amount as the discharge. The charge amount was managed by integrating the charge current values. Cycle temperature: 40 ° C atmosphere

[0018]

[Table 1]

After 100 cycles, the storage battery is heated to 25 ° C.
The battery was discharged at 5.6 A to 1.7 V / cell in the above atmosphere, and the SOC of each storage battery was examined. The results are shown in Table 2 and FIG. In the evaluation of each charging voltage in this test, the SOC at the start was 90% and 25.2 Ah.
Evaluation was made based on how much the capacity decreased after charge / discharge of the cycle.

[0020]

[Table 2]

As is clear from Table 2 and FIG. 1, the open circuit voltage is 0.18 V / cell or more and 0.68 V / cell or more.
No. which cycled at a charging voltage lower than the cell. 3-No.
It was found that No. 9 had a small capacity decrease and was preferable as a charging condition when a lead storage battery was used in PSOC.

No. 1 charged at 0.18 V / cell or less with respect to the open circuit voltage. 1 and No. Sample No. 2 had a remarkable tendency of insufficient charging and a large decrease in capacity. On the other hand, N was charged at a voltage of 0.68 V / cell or more with respect to the open circuit voltage.
o. In No. 10, the capacity was reduced despite not being insufficiently charged. This is considered to be because the adhesion between the positive electrode active material and the lattice was reduced as described above.

[0023]

Embodiment 2 Next, rated capacity, 20 Ah, nominal voltage, 1
Ten control valve-type lead-acid batteries for automobiles of 2 V were prepared, and first, 2 Ah was discharged at 4 A (0.2 CA), and the state of the remaining capacity of the storage battery was 18 Ah, and the SOC was 90%. At this time, the open circuit voltage of the storage battery was 12.7V. These storage batteries were charged and discharged at the same charging voltage as in Table 1. Charge
Details of the discharge conditions are shown below.

Discharge: Charge for 1 minute with a current of 40 A: Charge voltage: Maximum charge current of each charge voltage shown in Table 1: 80 A Charge: Charge the same amount as discharge. The charge amount was managed by integrating the charge current values. Cycle temperature: After charging and discharging for 1000 cycles under the above conditions in an atmosphere of 40 ° C., 2
In a 5 ° C. atmosphere, each storage battery was discharged at 4 A at a discharge end voltage of 1.7.
Discharge was performed to 0 V / cell, and SOC9 was applied as in Example 1.
Each charging voltage was evaluated based on how much the capacity decreased from 0% capacity 18Ah. The results are shown in Table 3 and FIG. 2, respectively.

[0025]

[Table 3]

As is clear from Table 3 and FIG. 2, the same results as in Example 1 were obtained also in the control valve type lead storage battery.

Next, in order to clarify the effect of the recovery charge shown in the item of claim 2 of the present invention, each storage battery is recovered and charged after the 4A discharge performed for evaluating each charge voltage in the second embodiment. Under the following conditions. (Charging conditions) Charging voltage: 14.4 V Maximum charging current: 80 A Charging time: 2 hours Temperature: 25 ° C. After charging, each storage battery was discharged at 4.0 A at 1.70 V.
/ Cell, and the recovery characteristics were evaluated. Table 4 shows the results.

[0028]

[Table 4]

As shown in Table 4, no. Except for 20 storage batteries, the battery was recovered to the rated capacity by the recovery charge. In this way, by performing the recovery charging periodically to recover the battery to the rated capacity, a stable life performance can be obtained when the lead storage battery is used in the PSOC. That is, PSO
This is because, when used at C, even if the difference between the predetermined SOC and the SOC obtained from the integrated value of the charging / discharging current values becomes large, the difference can be eliminated by the recovery charging.

The storage batteries of Nos. And 20 did not sufficiently recover the capacity even after the recovery charging. The cause of the capacity decrease when charging at such a high charging voltage is not insufficient charging,
It became clear that the adhesion between the positive electrode active material and the grid was reduced, and the capacity was fundamentally reduced.

[0031]

As described in detail above, in the control method in which the lead storage battery is used in the PSOC and the SOC is managed by integrating the charging / discharging current values, the charging voltage used in the PSOC is controlled. By charging at 0.18 V / cell or more and 0.68 V / cell or less with respect to the open circuit voltage of the lead storage battery, even if charge / discharge is repeated, there is no large deviation from a predetermined SOC in a short time, Furthermore, the difference can be eliminated by performing the recovery charge periodically, and a stable life performance can be obtained even under the use condition where the discharge frequency is high, and the industrial effect is great.

[Brief description of the drawings]

FIG. 1 is a diagram showing test results of Example 1 of the present invention.

FIG. 2 is a diagram showing test results of Example 2 of the present invention.

Claims (2)

[Claims] 1. A control method for using a lead-acid battery in a partially charged state and managing the charged state by integrating charging / discharging current values, wherein the charge voltage when used in the partially charged state is determined by the lead-acid battery. A method for controlling a lead storage battery, wherein the open circuit voltage is set to 0.18 V / cell or more and 0.68 V / cell or less. 2. The method of controlling a lead storage battery according to claim 1, wherein in the control of the partial charge state, a recovery charge is performed periodically.