Method of and system for determining the remaining energy in a metal fuel cell

#This invention relates generally to fuel cells, and, more specifically, to metal fuel cells, and measurements of remaining energy in metal fuel cells or electrochemical power systems employing the same.

#One technique for measuring the remaining energy of a metal fuel cell involves measuring the remaining amount of fuel that can be provided to the fuel cell from a source, such as a fuel tank or cartridge, coupled to the fuel cell. Unfortunately, however, this technique will not be accurate if the reaction medium in the fuel cell becomes saturated with reaction product before the remaining fuel can be consumed. In that case, a measurement of remaining energy derived from the remaining fuel will over-estimate the remaining energy in the fuel cell.

#One aspect of the invention comprises a method of measuring available energy in a metal fuel cell. The metal fuel cell utilized in accordance with this aspect has one or more reaction products of an electrochemical reaction occurring therein that are dissolved in a reaction medium to form a mixture having at least one electrical property. The method comprises measuring at least one of the electrical property(ies) of the mixture; and deriving an indication of the available energy of the fuel cell from the measured electrical property(ies). Suitable electrical property(ies) of the mixture that are measured in accordance with the invention include without limitation voltage potential, current, resistance, conductance, other electrical properties from which can be determined the concentration of one or more reaction products and/or the available energy in the fuel cell, and the like, and suitable combinations of any two or more thereof.

#The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating some principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.

#FIG. 1 is a simplified block diagram of an electrochemical power source system.

#FIG. 2 is a simplified block diagram of an alternate embodiment of an electrochemical power source system.

#Introduction to Fuel Cells And Electrochemical Power Systems Employing Fuel Cells

#A metal fuel cell is a fuel cell that uses a metal, such as zinc particles, as fuel. In a metal fuel cell, the fuel is generally stored, transmitted and used in the presence of a reaction medium, such as potassium hydroxide solution.

#A block diagram of a fuel cell is illustrated in FIG. 1. As illustrated, the fuel cell comprises a power source 102, an optional reaction product storage unit 104, an optional regeneration unit 106, a fuel storage unit 108, and an optional second reactant storage unit 110. The power source 102 in turn comprises one or more cells each having a cell body defining a cell cavity, with an anode and cathode situated in each cell cavity. The cells can be coupled in parallel or series, or independently coupled to different electrical loads. In one implementation, they are coupled in series.