JPH10134848A - Charging method for sealed lead-acid battery by oxygen cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve such an issue as the short life of a battery when charging and discharging are seldom conducted by discharging a fully charged sealed lead-acid battery by specified electric amount, and leaving the same in an open circuit state. SOLUTION: After a sealed lead-acid battery is fully charged, the battery is discharged by an electric amount of 1% or more of rated capacity, and is left in an open circuit state. It is particularly desirable that its discharged electric amount is set to be 10% or less. Its discharging is automatically conducted, or the discharged electric amount is reduced or released by a manual switch according to cases. When the battery is discharged and is left after full charging, the capacity of the battery is reduced by the discharged electric amount so that discharging exceeding 10% is not desirable since available charged electric amount is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for charging a sealed lead-acid battery by an oxygen cycle.

[0002]

2. Description of the Related Art Sealed lead-acid batteries using an oxygen cycle are not only used as an emergency power supply that is normally float-charged, but also used in many applications such as electric vehicles and various portable electric devices. In the latter, after discharging the battery, the battery is charged immediately by a constant current, a quasi-constant voltage or a constant voltage / constant current or any other suitable method, and is then ready to be discharged whenever the load requires it. In this type of application, the battery is most often left in a charged state, and the time between discharge and charge is often much shorter than the time left.

[0003] Even if a battery has a life cycle of 500 cycles in a bench test in which discharge and charge are continuously repeated, the cycle life becomes extremely long if the battery is left and discharged and charged in one day repeatedly. Shorter, 1/5 to 1/1
It turned out to be zero.

[0004] Conventionally, in order to completely charge the battery,
Proposal to perform constant-current charging, which is high voltage at the end of charging, in a short time, and to discharge only a very small amount of electricity less than 1% of the rated capacity to eliminate noble polarization of the positive electrode plate after charging is completed. However, these methods have not been able to extend the life of a battery that has been used for a long period of time.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problem of shortening the life of a sealed lead-acid battery when charging and discharging is rarely performed by the conventional charging method.

[0006]

The gist of the present invention is to discharge a sealed lead-acid battery fully charged in accordance with a standard method by an amount of electricity of 1% or more of the rated capacity and leave it in an open circuit state. The battery charger has a mechanism for automatically discharging the battery to 10% or less of the capacity and a mechanism for manually reducing or canceling the amount of discharged electricity after full charge.

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLE Next, the results of a charge / discharge cycle test of a sealed lead-acid battery having the same contents with a 5-hour rate discharge capacity of 5 amp-hours (Ah) were performed while changing the charging conditions and the standing time after charging. It is shown in FIG. Discharging was performed at a constant voltage and a constant current at a maximum voltage of 1.0 A at a final voltage of 1.70 V / cell for 18 to 21 hours, and one cycle was performed for 24 hours. The temperature was in a room temperature of 25 ± 5 ° C., and the life was determined when the discharge capacity reached 3.0 Ah.

[0007]

[Table 1] As is clear from Table 1, after fully charged, 1 to 10% of the rated capacity was discharged and left for 6 or 13 days, and the discharged and charged battery was continuously charged and discharged. Although the number of cycles was about 70% or more of the number, it decreased to less than half in the case of the battery left without discharging after charging.

[0008] A 1.0% discharge is enough to eliminate the noble polarization at the end of charging of the positive electrode plate. Therefore, the above results are not due to the elimination of the polarization of the positive electrode plate, but to other reasons.

In the positive electrode plate, water is consumed and reduced by charging, and sulfuric acid is generated. The electrolyte, which has a high specific gravity due to the sulfuric acid, sinks downward due to gravity.However, in a sealed lead-acid battery, the positive electrode active material is microporous and uses a retainer mat made of fine glass fiber as a separator. Therefore, the sedimentation rate of the high specific gravity electrolyte is small, and it is considered that the high specific gravity electrolytic solution exists for a long time during the standing after charging at the inside of the electrode plate or at the interface between the grid and the active material. . This is fundamentally different from a liquid battery. On the other hand, in the discharge after charging, the active material in the vicinity of the grid where the specific gravity of the electrolyte is high and the charging current flows reacts preferentially, so that sulfuric acid at the interface between the grid and the active material is consumed and the specific gravity decreases. In addition, it is considered that the cycle life including the prolonged standing was improved. In a sealed lead-acid battery, as is well known, the grid has lead-
The reason for this is that a calcium-based alloy is used, and the charge / discharge cycle life of the positive electrode plate becomes shorter as a battery with a higher specific gravity electrolyte has a passivation layer, that is, a so-called barrier, formed at the interface between the lattice and the active material.

[0010] Leaving the battery after it is completely charged is to reduce the capacity of the battery by the amount of discharged electricity. Therefore, discharging exceeding 10% is not preferable because the available amount of charged electricity is reduced. Therefore, in the experiment shown in Table 1, the discharge after full charge was 10 times of the rated capacity.
Stayed below the percent. If it is known that the next discharge will be performed without leaving the battery for a long time after charging, it is better not to discharge after full charge, so the charger manually reduces or eliminates the discharge. It is desirable to provide a mechanism for performing this.

FIG. 1 shows an example of a block diagram of a charging apparatus for performing the charging method according to the present invention. The charging device according to the present invention is provided with a discharge electricity amount setting device, a discharger, a manual switch, and the like, in addition to a normal charging device, and automatically detects a predetermined amount of electricity after the detection of the end of charging. ,
Alternatively, the discharge is released by a manual switch as occasion demands.

[0012]

Industrial Applicability The present invention has solved the problem of shortening the life of a sealed lead-acid battery used in rarely charged / discharged applications, and has high industrial utility value, and is particularly effective for storage battery users. is there.

[Brief description of the drawings]

FIG. 1 is an example of a block diagram showing a charging device for performing a charging method according to the present invention.

[Explanation of symbols]

Claims (3)

[Claims] 1. A seal by an oxygen cycle, which is completely charged according to a fixed method such as a constant current, a quasi-constant voltage, a constant voltage and a constant current, and then discharges an amount of electricity of 1% or more of a rated capacity to make an open circuit state. How to charge lead-acid batteries. 2. The charging method according to claim 1, wherein the discharge capacity is 10% or less of the rated capacity. 3. A charger having a mechanism for automatically performing the charging method according to claim 1 and a mechanism for manually reducing or canceling the amount of discharged electricity after full charge.