JPH06119942A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To lessen elusion of impurities from a battery, give it small size, high accuracy, and long life, and facilitate storage and management by including Ca ions in the electrolyte, and sensing the specific gravity of sulfuric acid from the Ca ion concentration using an optical ion sensor. CONSTITUTION:When the concentration of sulfuric acid varies, the Ca ion concentration in the electrolytic solution changes in accordance with the solubility product. With change of the Ca ion concentration, a fluorescent pigment consisting of acrydineorange derivative attached to an ion responsive film moves into and out of the interface of the film. With increasing sulfuric acid concentration, it moves apart from the film, and attaches to the film with decreasing. When coupled with ion exchanger of the film, the fluorescent pigment presents a greater intensity of fluorescence and slips off from the film. That is, the intensity of fluorescence lessens as going apart from the ion exchanger. The pigment is irradiated with Ar ion laser and excited, and the intensity of fluorescence is measured by a photo-electron multiplier tube through a diffraction lattice spectrograph, and the Ca ion concentration is determined from the intensity of fluorescence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead storage battery equipped with an electrolyte concentration sensor for detecting a charge / discharge state.

[0002]

2. Description of the Related Art As is well known, in a lead storage battery, the charge / discharge state can be accurately known by measuring the specific gravity or sulfuric acid concentration of the electrolytic solution. This is because sulfuric acid participates in the charge / discharge reaction, and the sulfuric acid concentration changes in proportion to the charge / discharge amount. Therefore, if the concentration of the electrolytic solution is known, it is possible to accurately know the charge / discharge state or the remaining capacity of the battery, that is, how much the battery is currently discharged, or how much can be discharged. If we could take a step further and develop a sensor that takes out the sulfuric acid concentration as an electric signal, this electric signal can be fed back to the charger to automatically control the charge / discharge state of the battery, which can contribute to maintenance-free maintenance of standby power supply equipment.

Against this background, Ca ²⁺ shown in FIG.
A method has been proposed in which the concentration of Ca ²⁺ contained in an electrolytic solution is detected as a sulfuric acid concentration using a calcium ion electrode by applying the law of solubility product that the concentration is inversely proportional to the sulfuric acid concentration (Patent application Flat 3-270326). However, this method has a large error because (1) the current distribution when the battery is charged and discharged is detected as noise in the form of a potential difference in order to detect the potential difference between the reference electrode and the electrode-type ion sensor, (2) sulfuric acid. Since a reference electrode such as a mercurial mercury electrode or mercuric chloride electrode is used, harmful impurities such as mercury and chlorine ions, which are harmful heavy metals, elute in the battery, and (3) it is difficult to miniaturize. there were.

[0004]

The present invention is characterized in that an optical fiber ion sensor is used as a sulfuric acid concentration sensor. (1) Since the optical fiber ion sensor detects with an optical signal, the potential difference due to the current distribution at the time of charging and discharging the battery (2) It is not an electrochemical electrode, so it does not damage the battery even if it is short-circuited. (3) No reference electrode is required. (4) Miniaturization by using optical semiconductor element. It is possible to eliminate the problems of the conventional ion electrode system.

The principle of sulfuric acid concentration detection by the optical fiber ion sensor will be described with reference to FIG. First, when the sulfuric acid concentration changes, the calcium ion concentration in the electrolytic solution changes according to the solubility product. When the calcium ion concentration changes, a fluorescent dye composed of an acridine orange derivative attached to the ion-sensitive membrane enters and leaves the interface of the membrane. When the concentration of sulfuric acid increases, it separates from the film, and when the concentration of sulfuric acid decreases, it adheres to the film. When the fluorescent dye binds to the ion exchanger of the membrane, the fluorescence intensity increases, and when it escapes from the membrane, that is, when it separates from the ion exchanger, the fluorescence intensity decreases.

The fluorescent dye is excited by irradiating it with light using an argon ion laser. The fluorescence intensity emitted by the excited fluorescent dye in the ion-sensitive film is dispersed by a diffraction grating and measured by a photomultiplier tube and a lock-in amplifier. There is a linear relationship shown in FIG. 3 between the logarithm of the calcium ion concentration and the fluorescence intensity, and the calcium ion concentration can be known from the fluorescence intensity. If the calcium ion concentration is known, the sulfuric acid concentration can be known from the relationship of the solubility products of calcium sulfate shown in FIG.

[0007]

EXAMPLE An example of the lead-acid battery of the present invention equipped with an electrolyte concentration sensor will be described below with reference to the drawings.

FIG. 4 is a schematic sectional view showing a state in which the optical fiber ion sensor is mounted on the lead storage battery. 1 is a battery case, 2 is a battery cover, 3 is a negative plate, 4 is a negative terminal, 5
Is a separator, 6 is a positive electrode terminal, 7 is an optical fiber ion sensor consisting of a main body 9 having a structure such as a screwing structure that can be easily attached to and detached from a battery case lid, 8 is an electrolytic solution made of dilute sulfuric acid, 10
Is a sensor output lead wire, 11 is a laser, a photomultiplier tube,
With a built-in lock-in amplifier, etc., the input information is processed by a microcomputer and the electrolytic solution concentration, electrolytic solution specific gravity, or battery remaining capacity is directly viewed in digital or analog display.
It is a capacity display converter that can be read directly.

When the concentration of the electrolytic solution was detected by charging and discharging the battery at various discharge rates with this device, the response speed was satisfactory and the measurement accuracy was ± 0.005 in the specific gravity of the electrolytic solution.
It was an excellent product within the range of.

[0010]

INDUSTRIAL APPLICABILITY The electrolyte concentration sensor used in the lead acid battery of the present invention is not affected by the charge / discharge current of the battery, does not elute impurities, is small in size, has high accuracy, and has a long life. Is easy, and its industrial value is extremely high.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between acid concentration and calcium ion concentration.

FIG. 2 is a schematic diagram showing an electrolyte concentration detection system using an optical fiber ion sensor.

FIG. 3 Fluorescence intensity-calcium ion concentration calibration curve diagram of the optical fiber ion sensor

FIG. 4 is a schematic sectional view showing the lead-acid battery of the present invention.

[Explanation of symbols]

 1 Battery Case 2 Lid 3 Negative Plate 5 Separator 7 Optical Fiber Ion Sensor 8 Electrolyte 11 Capacity Display Converter

Claims (1)

[Claims] 1. A lead-acid battery comprising an optical fiber ion sensor which contains calcium ions in an electrolytic solution and detects a specific gravity of sulfuric acid based on the calcium ion concentration.