JPH01253177A - Method for detecting degradated conditions in sealed battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for detecting the deterioration state of a sealed lead battery.

BACKGROUND OF THE INVENTION In recent years, sealed lead batteries have been widely used in uninterruptible power supplies such as UPS.

Sealed lead-acid batteries are sealed and require no maintenance because the cathode absorbs oxygen generated at the anode during charging. The problem when using this sealed lead battery for trickle applications is that it is difficult to detect the state of deterioration (life state) of the battery.

The deterioration factors of sealed lead batteries can be broadly divided into lattice elongation (corrosion) and moisture permeation. The deterioration factors and phenomena of sealed lead batteries are shown in 1ff.

Among these, it has been found that when the electrolyte decreases due to moisture permeation, the adhesion between the electrode plate and the separator deteriorates, resulting in an increase in internal resistance.

Therefore, it is possible to detect the state of deterioration by measuring the internal resistance of the sealed lead battery using a 1 km meter or the like.

Problems to be Solved by the Invention However, when the grid deteriorates due to corrosion and elongation, the internal resistance does not change much, making it unsuitable for detecting the life state. In an accelerated life test by raising the ambient temperature and replenishing water at regular intervals, the lifespan was increased by intentionally corroding and elongating the grid.
Figure 1 shows the changes in the discharge capacity and internal resistance when the battery was used as a battery, and when the electrolyte was intentionally reduced due to moisture permeation without water replenishment to achieve the maximum lifespan. As shown in FIG. 1, when the lattice reaches the end of its life due to elongation and corrosion, there is little change in internal resistance.

Furthermore, in lead batteries, the specific gravity of the electrolyte is generally measured as one parameter for examining the battery condition. However, since sealed lead batteries are sealed, it is difficult to measure specific gravity. Further, even if measurement is possible, if the electrolyte decreases due to moisture permeation, only the moisture in the electrolyte decreases and the specific gravity may increase, so it is not suitable for detecting the life state.

Means for Solving the Problems The present invention has been made to solve the above problems.
The method is characterized in that the internal resistance of the sealed lead battery is compared with the initial value of the internal resistance of the sealed lead battery with the values measured at a certain frequency of 100 Hz or more and at a certain frequency of less than 100 Hz.

Operation The present invention has the above-mentioned characteristics, and thus makes it possible to detect the deterioration state of sealed lead-acid batteries in trickle applications.
Even if deterioration occurs due to corrosion), the state of deterioration can be detected. This takes advantage of the fact that internal resistance changes with frequency when deterioration progresses.

Figure 2 shows an example of the frequency-internal resistance characteristics of a sealed lead battery. The lower the frequency, the higher the internal resistance.

FIG. 3 shows an example of the frequency-internal resistance characteristics at the initial stage and after the life when the life is reached due to elongation (corrosion) of the lattice in the accelerated life test. At a frequency of 100 Hz or more, there is little difference between the initial state and the end of life, but at a frequency of less than 100 Hz, the internal resistance after life becomes high. Therefore, if the lattice deteriorates due to stretching.

The end-of-life state can be detected by measuring the internal resistance at a frequency of 100 Hz or less.

Further, in the accelerated life test, an example of frequency-internal resistance characteristics at the initial stage and after the life when the life is reached due to moisture permeation is shown in FIG. The internal resistance is high at any frequency.

Therefore, if the internal resistance measured at a high frequency is higher than the initial value, it is determined that deterioration due to moisture permeation has occurred. If the internal resistance is higher than the initial value, it is determined that deterioration due to lattice elongation (corrosion) has occurred.

Example An embodiment of the present invention will be described.

FIG. 5 is an explanatory diagram showing a method for measuring internal resistance. Approximately 0
．． The internal resistance is determined by passing an alternating current of 01 OA'-p and measuring the alternating current voltage component included in the battery voltage.

Figure 6 is a diagram showing the correlation between internal resistance and discharge capacity during the test when the service life is reached due to moisture permeation at a frequency of I KHz, and Figure 7 is a diagram showing the correlation between the internal resistance and discharge capacity during the test when the service life is reached due to moisture permeation. FIG. 3 is a diagram showing the correlation between the internal resistance during the test and the discharge capacity when the battery reaches the end of its life.

If the internal resistance of the sealed lead battery measured at the frequency I KHz is higher than the initial value, it is determined that deterioration due to moisture permeation has occurred, and from Figure 6, the deterioration state of the sealed lead battery (discharge capacity can be estimated and , even if the internal resistance of the sealed lead-acid battery measured at the frequency I KHz remains unchanged from the initial value.
Frequency] If the internal resistance due to OHz is larger than the initial value, it is determined that deterioration due to grid elongation (corrosion) has occurred, and the deterioration state (discharge capacity) of the sealed lead battery can be estimated from FIG.

Effects of the Invention As described above, according to the present invention, the internal resistance of a sealed lead battery is measured at high and low frequencies.
This has the effect that it is possible to estimate the state of deterioration in both cases when deterioration occurs due to corrosion.

In addition, when a short circuit occurs due to the elongation of the lattice and the battery reaches the end of its life, the charging current increases. By detecting this current, it is possible to detect the end of the battery life. In the worst case, this can lead to a dangerous situation of thermal runaway. Therefore, the present invention has the advantage of being able to detect the state before short circuit when deterioration occurs due to lattice elongation. The value is extremely great.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing changes in discharge capacity and changes in internal resistance in an accelerated life test of a sealed lead battery; Fig. 2 is a characteristic diagram showing an example of frequency-internal resistance characteristics of a sealed lead battery;
Figure 3 is a characteristic diagram showing an example of frequency-internal resistance characteristics when a sealed lead battery reaches the end of its life due to lattice elongation (corrosion), and Figure 4 shows an example of the frequency-internal resistance characteristic when a sealed lead battery reaches the end of its life due to moisture permeation. A characteristic diagram showing an example of frequency-internal resistance characteristics. Fig. 5 is an explanatory diagram showing a method for measuring the internal resistance of a Nord lead-acid battery according to the present invention. Fig. 6 shows a graph showing the grid elongation (corrosion) of a sealed lead-acid battery at a frequency of 10 Hz. Figure 7 is a characteristic diagram showing the correlation between the internal resistance during the test and the discharge duration when the life is reached at 1 KHz. FIG. 3 is a characteristic diagram showing the correlation between internal resistance and discharge duration. 1 is an oscillator, 2 is a voltage-1 optical converter, 3 is a sealed lead battery to be measured, 4 is an AC voltage component amplifier, and 5 is an oscilloscope.

Claims (1)

[Claims] Deterioration of a sealed lead battery, characterized by comparing the internal resistance of the sealed lead battery with the initial value of the internal resistance of the sealed lead battery and the values measured at a frequency of 100 Hz or higher and at a frequency of less than 100 Hz. Condition detection method.