US 4,045,721 A · Electro-chemical concentration transducer and its use to measure and control acid strength and storage battery charge

Abstract

A simple and rugged transducer has an electric potential output which is a measure of the concentration of a sensed sulphuric acid. The small temperature coefficient of potential is linear and correctable. The resistance of the transducer is a strong and negative function of temperature. It is used to measure electrolyte temperature and to compensate variable characteristics of batteries and reagents. A battery is automatically charged in 21/2 hours. Both transducer potential and resistance are used in a new and doubly responsive closed loop system which regulates charging current so that it is as high as can safely be used. A battery gage conveniently shows available charge or energy at the present temperature of the battery. Chemical reagent strength is measured and controlled. The transducer uses the discovery that an electric potential of 40 millivolts exists between two electrodes -- one in contact with the electrolyte of a fully charged lead-acid cell, and the other in contact with the weaker electrolyte of a discharged cell -- when the electrolytes are electrolytically joined by an electrolyte in an insulated container constructed to prevent mixing of the electrolytes. The strength of different types of electrolytes is sensed in a similar structure. Theory is given and preferred transducers are described. These are matched to measuring and controlling instruments using an improved method and integrated circuit amplifier.

Claims15

Dependent claims

A transducer for sensing electrolyte concentration and producing an electric signal potential output proportional to a difference in concentration between a first electrolyte having a first concentration and a second similar electrolyte having a second concentration, comprising in combination;

a first electrode coupled to a first terminal and having a surface area in contact with said first electrolyte contained in a first container, and
a second electrode coupled to a second terminal and having a surface area in contact with said second electrolyte contained in a second container, and
an open joining container having a first end opening into said first container and a second end opening into said second container, and
adapted by construction means to be filled with an electrolyte to form a joining electrolyte making electrolytic connection with said first electrolyte at said first end and also making electrolytic connection with said second electrolyte at said second end to thereby establish a
direct electrolytic connection between said first and said second electrolytes so as to permit a measuring current considerably in excess of that conventionally associated with glass membrane half cell usage to flow through said joining electrolyte to said first and second electrolytes and said first and second electrodes to said first and second terminals,
said open joining container also constructed in elongated form wherein the ratio of the length to the square root of the effective cross-section area is greater than 10 so as to generally prevent mixing by unintentional passage therethrough of said first and said second electrolytes so that neither said first nor said second concentration is altered by more than an allowable amount during the useful life of said transducer.

3 more elements

A transducer for sensing electrolyte concentration and producing an electric signal potential output proportional to a difference in concentration between a first electrolyte having a first concentration and which may have large electric current flowing therein and a second similar electrolyte having a second concentration, comprising in combination;

a first electrode coupled to a first terminal and having a surface area in contact with said first electrolyte in a first container, and
a second electrode coupled to a second terminal and having a surface area in contact with said second electrolyte in a second container, and
a joining container having a first end opening into said first container and a second end opening into said second container, and
construction means whereby said first electrode is positioned in close proximity with and directly opposite said first end of said joining container so as to
thereby substantially reduce an extraneous potential across said terminals in the event of said large electric current in said first electrolyte,
said joining container adapted by construction means to be filled with an electrolyte to form a joining electrolyte making contact with and electrolytically connecting said first and second electrolytes so as to permit a
measuring current to flow through said joining electrolyte and said first and second electrolytes to said first and second electrodes and said first and second terminals under the stimulus of said potential,
said joining container also having construction means to generally prevent mixing by unintentional passage therethrough of said first and said second electrolytes so that thereby neither said first nor said second concentration is altered by more than an allowable amount during the useful life of said transducer.

5 more elements

Dependencies are inferred from the claim text.

Electro-chemical concentration transducer and its use to measure and control acid strength and storage battery charge

Life of this patent

Electro-chemical concentration transducer and its use to measure and control acid strength and storage battery charge

Life of this patent

Abstract

Claims15