Method and system for detecting leakage of energy storage structure liquid

A method and system for detecting liquid leaked from an energy storage structure, e.g., a battery is provided. One embodiment includes a sensor that detects the leaked electrolyte as it leaks through a breach in the wall retaining the electrolyte in the battery. The sensor has a sheet-like layer with a conductive surface and an electrical connection to a first interface. The sensor is positioned substantially flush to the battery wall, so that leaking electrolyte contacts the sensor. If the battery has a case, there is a first external communication point in electrical communication with the first interface. In the absence of leaked electrolyte there is substantially no electrical connection between the first external communication point and either of the terminals as indicated by a very high resistance. When leaked electrolyte is present there is an electrical connection between the first external communication point and either of the terminals.

FIELD OF THE INVENTION

The present invention relates generally to energy storage systems, and more particularly to a system for detecting leakage of electrolyte from batteries.

BACKGROUND

Cracked cells or monoblocks cause electrolyte to leak through the wall into the battery case. Electrolyte can also leak if the battery is overcharged, as the overcharging can cause the electrolyte to spew out of the cells or monoblocks. Leaked electrolyte corrodes the battery case, and it is particularly corrosive to metal battery cases and the trays securing the battery, as well as adjacent equipment.

SUMMARY OF THE INVENTION

A method and system is provided for detecting liquid leaks, such as for example electrolyte leaked from a first structure adapted to store a liquid used in an energy storage system, for example a battery. One embodiment of the system comprises a second structure that serves as a sensor that detects electrolyte as it leaks through a breach in a battery wall retaining the electrolyte or when it spews out of a battery cap and drips down to the sensor. The second structure is positioned in proximity to a surface of the first structure. A first conductor is coupled to a first area of the second structure. The leak detection system includes a connectable sensing system adapted to sense a change in at least one electrical value associated with at least one area of the second structure, where the sensing system is coupled or connectable to the first conductor. The second structure is adapted such that an electrical value associated with the second structure will change when at least some of the liquid comes in contact with the second structure.

An embodiment of a method associated with the invention tests the conductivity between terminals coupled to each liquid permeable layer, and the method works irregardless of the electrical values or measurements of the battery case. The system is suited to easily and rapidly check for the presence of leaked electrolyte with the battery in place, and lends itself to automation and hierarchical network testing. This embodiment of the invention also potentially lends itself to determining the size of the breach, as the larger the opening the less resistance through the breach.

DETAILED DESCRIPTION OF THE INVENTION

An electrolyte detection system and method is provided for a variety of battery types. If the battery has a conductive case, then the detection system typically requires a sensor with an insulating layer.

One example of a dry cell battery is shown inFIG. 1having a cathode192with a positive terminal104, an anode194with a negative terminal102, an electrolyte200and an insular wall196. In the illustrated battery100, the anode194is a cylindrical layer of zinc, and the electrolyte200is typically a moist paste of ammonium chloride, zinc chloride and fillers. The cathode192can be carbon coated with manganese oxide. The insular wall196is comprised of a paper layer, and as the zinc is consumed the electrolyte moves closer and closer to the paper layer, and toward the end of the battery's life, it is common for the electrolyte to tear the wall and for electrolyte to leak out. It should be noted that an embodiment of the invention can be adapted for use with any type of liquid encapsulating a system associated with energy storage.

FIGS. 2-3ashow several embodiments of the invention for detecting and mitigating damage caused by leaking electrical storage system liquids, including electrolyte. A sleeve-like sensor20is illustrated inFIG. 2. The sensor20has a sheet-like layer with a conductive surface22, and can be made from a foil sheet, layer, perforated foil sheet, a mesh, a grid of wires, a conductive pad, or a combination thereof. A shape for the sheet-like layer can be formed to ensure the conductive surface is substantially flush to a battery external surface, and is adapted to ensure contact with leaked electrolyte or liquid as it leaks out of the battery's external surface, such as a side wall.FIG. 2aillustrates the battery100covered with a leak sensor (e.g.,FIG. 2, sensor20) in accordance with an embodiment of the invention. The sensor has an electrical interface24that can be coupled with a multimeter or another electrical value or measurement test device to detect changes in electrical values or measurements associated with the sensor to include determining the resistance between one of the terminals104,102and the first interface24. For example, if resistance measured between two points in the sensor or between the first interface24and terminals104or102is very high, there is substantially an open circuit, as there is no conductive path (i.e. leaked electrolyte) between a terminal and the first interface. A lower resistance indicates that electrolyte has leaked.

InFIG. 3, sensor20′ includes an absorbent permeable layer30that collects leaked electrolyte and a sheet-like layer with a conductive surface, wherein the sensor20′ prevents or impedes damage or corrosion to adjacent equipment or structures from electrolyte (not shown) leaked from an energy storage device. The sheet-like layer can be in contact with or proximity to a container having a liquid used in an energy storage system, such as a battery containing electrolyte, such that the liquid is detected after it leaks from the container. Referring toFIG. 3a, battery100is shown with a rupture120in a wall196, and electrolyte10leaking down onto a pad-like sensor20′ having an absorbent layer30. In this embodiment the sensor can be flush or not flush against an energy storage structure, e.g. a battery, side wall196; however, sensors not flush with a battery wall may be somewhat slower to detect the electrolyte than a sleeve-like embodiment illustrated inFIG. 2.

FIG. 4illustrates a sensor20″ that has a sheet-like layer with a conductive surface22with a first interface24, an absorbent layer30that collects leaked liquid, e.g. electrolyte, and an electrically and physically insulating layer as well as a conductor26having coupling28which can be connected to an electrical value measuring device or another conductor. The absorbent layer30and the conductive layer22each have distinct electrical values associated with a state without leaked electrolyte in contact with at least one of the layers. The conductivity of the absorbent layer30increases as more electrolyte is absorbed, while the electrical value of the conductive layer22is substantially conductive or nonconductive, depending on whether electrolyte is in contact with an area or surface of the absorbent layer30. An electrical path can be detected between a point within the energy storage device containing electrolyte and the sensor20″ by means of detecting changes in electrical values which occur when a leak of electrolyte occurs. Other electrical value measurements related to the sensor20″ and an energy storage structure the sensor is placed in proximity with such as, for example, resistance values, can also vary when liquid leaked from the energy storage structure comes into contact with the sensor20″. The insulating layer would be useful in a sleeve-like version of a leak sensor, such as shown inFIG. 2, as it provides a protective layer between the battery and a user of a battery, trapping electrolyte between the insulating layer40and the battery wall.

FIG. 5illustrates a lead acid battery100a. The case202is cut away revealing the wall196which has an aperture or rupture120, through which sulfuric acid can leak. The battery case of a lead acid battery100aand other monoblock batteries can be made of a polymeric material selected to be nonconductive, or made of metal, and therefore conductive. The battery100ahas electrodes192,194adapted for use in charging or discharging the battery100a. If a battery case is conductive, the case202can carry a current, and electrolyte that breaches the wall196causes the battery to drain down. If sufficient acid leaks, irrespective of the type of case, the cell will be dry and substantially nonconductive.

FIG. 6illustrates a lead acid battery fitted with an embodiment of the invention for detecting electrolyte. The battery monoblock walls are substantially flush to the conductive surface of the sensor20′″, such that the sensor contacts the leaked electrolyte as it leaks out of the one or more cells or monoblocks. The sensor's sheet-like conductive surface layer provides an electrical conductive path to the leaked electrolyte and an electrical connection to a first interface when leaked electrolyte comes into contact with the sensor20′″. A first external communication point28ais in electrical communication with the first interface24through the first conductive element26(e.g., an electrical wire). In the illustrated embodiment, the conductive surface layer is cut away to enable the reader to see underlying slit or rupture120in the wall196. The battery case of illustrated lead acid battery100ais nonconductive, and therefore no insulating layer is required, but optionally could be included. If the case were conductive, then the sensor would have an electrically and physically insulating layer between the layer having a conductive surface and the battery's case202.

Referring toFIG. 6, leakage can be determined by testing the connection between the first external communication point28aand the terminal192, using for instance a multimeter300. Alternatively, multimeter300can be coupled with another terminal, e.g.,194, of the battery. Note in the illustrated embodiment, the battery100ahas a second communication point28b. The second communication point28bcould be a redundant connection to the sensor, or the battery could have a plurality of corresponding sensors, for instance one on each side of the battery. The communication point28is illustrated as protruding; however, it could alternatively be recessed (e.g., a receptacle that accepts plugs or prongs), thereby preventing accidental contact with equipment or personnel. The corresponding sensor has a corresponding communication point. The plurality of corresponding sensors would enable each side wall to be tested individually in order to isolate where the wall had failed. This capability could be utilized in engineering new batteries and in analyzing flaws in a manufacturing process.

FIG. 7illustrates a network50of batteries100a,100a′,100a″, and100a′″. The individual batteries are in electrical communication with a controller260,260′,260″, and260′″ on a network bus, such as an I2C bus, therein allowing remote analysis of multiple batteries. A microprocessor would typically sample the sensors on the batteries and relay the information to a processor. The microprocessor could further comprise a transmitter that communicates readings to the processor or other digital device that calculates the electrical values or measurements and thereby measures the electrical values or measurements and therefore the presence or absence of leaked electrolyte.

FIG. 8is a diagrammatic view of one embodiment of the invention80, where a common commercial battery100bis seated in a holder/shelf70fitted with a sensor20to detect and collect leaked electrolyte. The circuit for the battery has a switch72and a resistance74. The circuit for the system includes a detection actuating switch76, and an informational device302comprised of an electrical value or measurement interpretation microcontroller and an indicator such as, for example, a visual indicator (e.g., a liquid crystal display), a light source such as an LED, a luminescent strip, an electroluminescent lamp, an incandescent bulb or neon light, and an audible alarm such as a buzzer or a beeper. When switch76is closed detection can be activated regardless whether switch72is open or closed.

An exemplary method for detecting that electrolyte has leaked from a battery having cells or monoblocks can comprise the following steps: providing a battery, if not already present, with a sensor comprised of a sheet-like layer having a conductive surface that is an electrically conductive path to leaked electrolyte and an electrical connection to a first interface, where the conductive surface is in contact with an insular wall of the battery that retains the cell's or monoblock's electrolyte. The sensor substantially blankets the insular wall such that if there is a leak of the electrolyte it intersects the conductive surface. Then, measuring the electrical values or measurements between the first interface and either a positive or a negative terminal of the battery to confirm that there is substantially no electrical connection between the first interface and either of the terminals as indicated by a very high resistance; and monitoring periodically that no electrical connection exists therein affirming that there has been no leakage of electrolyte, nor that a new electrical connection has been created between the first interface and either of the terminals, nor that there is an electrical path from the sensor through the wall to the terminals.

Another exemplary method can include the steps of: providing the battery with a case; providing the sensor with an electrically and physically insulating layer between the conductive surface and the battery's case, and a first external communication point in electrical connection with the first interface; and testing to confirm that there is not a conductive pathway from either terminal to the battery case. The method can additionally comprise the step of: providing an absorbent material that collects leaked electrolyte.

Another exemplary method for detecting that electrolyte has leaked from a battery can comprise the step of adapting the battery with the sensor. The adapting step preferably comprises the steps of: determining the bottom and side surface area dimensions and shape of an insular wall of the battery that retains the cell's or monoblock's electrolyte; fabricating a sensor comprised of a sheet-like layer having a conductive surface that is an electrically conductive path to leaked electrolyte and an electrical connection to a first interface, where the sheet-like layer has a shape and surface area that is approximately the same as the bottom surface area dimensions and shape of the battery; positioning the battery in contact with the conductive surface of the sheet-like layer and all layers of the sensor are fabricated of materials selected to be resistive to corrosion by the leaked electrolyte; and measuring the electrical values or measurements between the first interface and either a positive or a negative terminal of the battery to confirm that there is substantially no electrical connection between the first interface and either of the terminals.

The shape and surface area of the sheet-like layer can be inclusive of side surface area dimensions and shape of a battery, as well as a bottom side of the battery. It should be further noted that in all embodiments discussed herein, the term “sheet-like layer”, “sleeve-like” or “pad-like” can refer to a liquid permeable conductive layer or structure as well as a non-liquid permeable conductive layer or structure used in cases such as, for example, where an absorptive pad is between the sheet-like layer and battery which contains electrolyte and the absorptive pad is used to contain leaked electrolyte. A battery can be positioned in contact with a bottom and side conductive surface of the sheet-like layer as described above.

It is to be understood that the foregoing description and specific embodiments are merely illustrative of the best mode of the invention and the principles thereof, and that various modifications and additions may be made to the invention by those skilled in the art, without departing from the spirit and scope of this invention, which is therefore understood to be limited only by the scope of the appended claims.