JPH08308114A - Method for judging service life of sealed lead storage battery - Google Patents

Abstract

PURPOSE: To provide a method which can judge the service life of one unit battery without discharging electricity from the battery by stopping the charging operation of the battery by detecting the terminal voltage of the battery when the charging current becomes stable and judging the service life based on the difference between the detected minimum and maximum terminal voltages. CONSTITUTION: When a battery row is constituted by connecting in series nine sealed lead storage batteries having a nominal voltage of 12V and rated capacity of 6.5Ah as unit batteries, the difference between the maximum and minimum voltages of one unit battery being charged can be easily measured as compared with the charging voltage of the unit battery and the transition of the measured values well correspond to the transition of the discharge characteristic of the whole battery row. By utilizing this relation, it is contrived to judge the service live of each unit battery by making an alarm to be issued when the difference between the maximum and minimum values of the charging voltage becomes larger than a preset prescribed value. Therefore, it becomes unnecessary at the time of judging the service life of each battery to stop the operation of a device incorporated with the battery row, because the service life can be judged when the maximum and minimum values of the charging voltage of each battery are measured and the values can be measured while the battery row is charged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a life determining method for a sealed lead-acid battery used in equipment for power failure compensation such as an uninterruptible power supply.

[0002]

2. Description of the Related Art An uninterruptible power supply system for compensating for commercial power outages does not require a special storage battery, nor does it require replenishment of water or even charging, and so on. The use of storage batteries has increased.

[0003]

In the use of this sealed lead-acid battery, while the above advantages are recognized,
There is an inconvenience that it is not possible to measure the specific gravity of dilute sulfuric acid as an electrolytic solution to determine the life and other characteristics of the storage battery due to its structure.

Therefore, the present invention provides a method for determining the life of a sealed lead acid battery in the case of a power failure compensation application in which a plurality of unit lead batteries composed of sealed lead acid batteries having such mechanical characteristics are connected in series and used. The purpose is to do.

[0005]

According to the present invention, there is provided a method for determining the life of a sealed lead acid battery, which is a constant voltage charging method in which a plurality of unit lead acid batteries composed of sealed lead acid batteries are connected in series and commercial power is supplied. This is a method for determining the life of a sealed lead-acid battery in equipment for compensating for power outages that is being charged by means of measuring the terminal voltage of each unit battery at the time when the charging current is stable and determining the minimum and maximum values of those charging voltages. It is characterized in that the difference between the values is detected and the life is judged based on the value of the difference.

In this case, an alarm may be issued when the difference between the minimum value and the maximum value of the charging voltage exceeds a predetermined value, or the storage battery may be activated by the alarm. Disconnect from the charging circuit to discharge,
You may make it investigate the discharge characteristic.

The unit storage battery may be a 2V single-cell storage battery or a 2V single-cell storage battery.
It is also possible to divide by any number such as six or six, or to adopt a storage battery of 6V or 12V incorporated in one monoblock battery case as the unit storage battery.

[0008]

In the method for determining the life of the sealed lead-acid battery, the determination that the performance of the storage battery is deteriorated is made by efficiently detecting that the variation in the charging voltage of the unit storage battery is large. Is.

In the use for the power failure compensation in which the sealed lead acid battery is always charged at a constant voltage, the typical failure modes of the battery are (1) increase in internal resistance due to depletion of water in the battery, ( 2) A short circuit between the anode and the cathode due to expansion of the anode plate lattice or active material is often observed. Here, (1) is an increase in the charging voltage of the storage battery,
In (2), the charging voltage drops even if the short circuit between the anode plate and the cathode plate is slight. Of course, in this case, the total voltage applied to the storage batteries connected in series is considered to be a constant value.

In the above (1) and (2), one of the charging voltages is high and the other is low, but both of them show a value in which the discharge performance of the storage battery is deteriorated (deteriorated).

If a storage battery having a low charging voltage is generated due to a minute short circuit or the like generated inside the storage battery among the unit storage batteries being charged, the unit storage batteries connected in series inevitably have the same charging voltage. Something will be higher.
Then, if the battery is charged as it is, that is, if the battery is used continuously, the water content in the electrolytic solution tends to decrease due to electrolysis in the storage battery having a higher charging voltage. It is inevitable that the greater the decrease in water content, the greater the internal resistance of the storage battery, and the higher the charging voltage. That is,
Among the unit storage batteries connected in series, the one with the highest charging voltage and the one with the lowest charging voltage are selected, and the difference between them is continuously or periodically observed (measured), and there is the difference value. When the value exceeds the value, it can be determined that the discharge characteristic of the entire storage battery cannot maintain the required value. This is because the discharge characteristics of the storage battery are highly dependent on the value of its internal resistance. In particular, when the discharge rate is large, that is, when the battery is discharged at a current that is relatively large compared to the rated capacity of the storage battery, the ratio that depends on the internal resistance increases, so the relationship between the increase in internal resistance and the decrease in discharge characteristics It will appear clearly.

As is clear from the above description, the characteristic of the life determination of the storage battery by the method of the present invention is that it is not necessary to stop the charging operation of the storage battery and perform the discharge.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

First, a sealed (cathode absorption type) lead acid storage battery having a nominal voltage of 12 V and a rated capacity (20 hour rate) of 6.5 Ah was used as a unit storage battery, and nine battery cells were connected in series to form a storage battery array. Next, this battery array was incorporated into a UPS (uninterruptible power supply) and a continuous energization test was conducted at room temperature. The charging voltage was kept at 123.3 ± 0.9V. In this storage battery row, the measurement result of the maximum voltage difference between the charging period and the unit storage battery was as shown in FIG.

The relationship between the charging period and the dischargeable time of the storage battery, which was measured at the same time as the measurement of FIG. 1, was as shown in FIG. Furthermore, FIG. 3 shows the voltage difference between the maximum value and the minimum value of the charging voltage, based on the average charging voltage.

As is apparent from FIGS. 1 to 3, the maximum value (curve in FIG. 3) and the minimum value among the charging voltages of the unit storage batteries being charged by the determination method of the present invention are shown. As shown in FIG. 1, the voltage difference of the existing one (curve in FIG. 3) is a large value that is easy to measure, that is, a measurement error is less likely to occur, and the shape of the transition of this measured value is It can be seen that there is a good correspondence with the transition of the discharge characteristics (discharge time) of the entire storage battery array shown in FIG. By using such a correspondence relationship, when the difference between the maximum value and the minimum value of the charging voltage becomes larger than a predetermined value that is determined in advance, an alarm is issued and the life of the storage battery is determined. Good. Alternatively, the storage battery may be disconnected from the charging circuit by an alarm and its discharge characteristic may be examined.

The transition of the voltage of each of the unit storage batteries showing the maximum charging voltage (curve in FIG. 3) and the minimum charging voltage (curve in FIG. 3) is as follows.
As is clear from FIG. 3, it does not show a very good agreement with the shape of the change in the dischargeable time of the storage battery shown in FIG.

[0018]

The cause of the high charging voltage of the unit storage battery in the storage battery array is, for example, the main cause of depletion of the electrolytic solution in the storage battery, and the cause of the low charging voltage is, for example, that of the cathode plate. Factors such as inactivation and the occurrence of minute short circuits between the cathode and anode plates are considered. That is, it is considered that the cause of the charging voltage of the unit storage battery in the storage battery array being high and the cause of being low are different, but the determination method proposed in the present application for tracking the change in the voltage value that includes both of them is This is an effective and simple method for diagnosing the discharge characteristics of the entire storage battery array, that is, when the storage battery array is viewed as an integrated storage battery.

Since the life determining method of the present invention can be measured on the basis of the charging voltage of each unit storage battery therein while the storage battery train is being charged, an apparatus (system) incorporating the storage battery train can be used. ) It is not necessary to stop driving and measure.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the difference between the maximum value and the minimum value at each measurement point of the charging voltage of a unit storage battery in a storage battery row and the number of years of charging.

FIG. 2 is a diagram showing a transition of a dischargeable time of a storage battery array measured at the same time as the measurement of FIG.

FIG. 3 is a diagram showing the maximum value and the minimum value at each measurement point when the charging voltage of the unit storage battery shown in FIG. 1 is measured, based on the average charging voltage.

Claims (3)

[Claims] 1. A sealed lead-acid battery in a device for compensating for a power failure, which comprises a plurality of unit lead-acid batteries, which are sealed lead-acid batteries, which are connected in series and are constantly charged by a constant voltage charging method when commercial power is supplied. It is a life judgment method that measures the terminal voltage of each unit storage battery when the charging current is stable, detects the difference between the minimum value and the maximum value of those charging voltages, and determines the life based on the value of the difference. A method for determining the life of a sealed lead-acid battery, characterized by making a determination. 2. The seal according to claim 1, wherein an alarm is issued when the difference between the minimum value and the maximum value of the charging voltage becomes larger than a predetermined value. Lead-acid battery life judgment method. 3. The method for determining the life of a sealed lead acid battery according to claim 2, wherein the storage battery is disconnected from the charging circuit and discharged by the alarm, and the discharge characteristic is examined.