Alliedsignal Inc.

Other

Honeywell International Inc.

Patrick M Rudai

Thirumalai G Palanisamy

Harmohan N Singh

Steven Hoenig

Alpesh Patel

Deficiencies in the electrolyte level of the cells of NiCd battery can be detected by measuring the internal resistance of the cells. Initially, data is collected for a battery type and capacity, correlating measured internal resistance with the amount of water that must be added to bring the cell resistance to an acceptable value. Subsequently, cells of other batteries of the same type and capacity can be measured to determine how much water must be added and the levels quickly restored. The polarization value of the cells can be used lieu of the internal resistance in the same fashion.

Method for determining amount of water to be added to a NiCd cell

A method and apparatus for diagnosing the status of a battery having high and low voltage plateau states corresponding to its state of charge in which the battery open circuit voltage is measured (S,) to determine its voltage state and its internal resistance also is measured (S,). A battery having a low voltage state (S,) is tested to determine if its internal resistance is greater than a predetermined maximum resistance (S,) and if it does the battery is considered as possibly having a low electrolyte level, and if it does not the battery is subjected to a current ramp test to determine from the voltage response a point of current transition (S,) due to a battery chemical gassing reaction. The battery state of charge (S,) is determined from curves or algorithms of state of charge versus current transition. Each of a battery of high voltage state (S,) whose internal resistance is less than the maximum internal resistance and one whose internal resistance is greater than the maximum internal resistance and has been subjected to reconditioning by applying successive current pulses (S,, S,) to reduce its internal resistance is subjected to a current ramp test (S,) to determine the point of current transition and the state of charge of such battery is determined (S,) from a different set of curves or algorithms of state of charge versus current transition. Capacity of a battery of the two voltage state types is determined by charging it to its capacity (S,), applying a current ramp (S,) to determine the point of current transition and determining capacity from curves or algorithms of battery capacity versus current transition (S,).

Method and apparatus for analyzing an AgZn battery

A system and method for comprehensive analysis of a multi-cell battery, such as of the nickel-cadmium type, on an individual cell level basis and overall battery basis. For an unsealed battery, which affords access to the individual battery cells, (FIG. 2) tests are carried out to determine the presence of any shorted or reversed cells, and these can be repaired or replaced ((6)-(11)). The individual cells are then tested for sufficient electrolyte on the basis of comparing the cell internal resistance to a maximum internal resistance for the cell and electrolyte added as needed ((12)-(15)). A sealed battery, to which there is no access to the individual cells, is first tested for shorted or reversed cells on a battery level basis ((16)-(19)). A sealed battery that passes this test ((20)-(22)) and an unsealed battery whose individual cells have been found to be satisfactory in its prior tests are subjected to further testing on a battery level basis for: (a) overall internal resistance to determine if it exceeds a given maximum value internal resistance, this indicating that the battery is defective (23); and (b) actual capacity as compared to its rated capacity ((24)-(30)). A battery whose actual capacity is greater than its rated capacity is tested for a memory effect and the memory effect problem is corrected if found to be present ((31)-(36)).

Method and apparatus for analyzing nickel-cadmium batteries

The invention provides for a timesaving method of determining whether a nickel cadmium (NiCd) battery is stricken with memory effect. A fully charged NiCd battery under test ('test battery') is subjected to a positive sloped current charge ramp and then a negative sloped current charge ramp while continuously monitoring the battery terminal voltage. The maximum measured terminal voltage of the test battery is compared to the measured terminal voltage of a NiCd battery of the same nominal voltage and capacity and known not to have memory effect ('normal'battery). A NiCd battery is determined to have memory effect if the maximum voltage of the test battery exceeds the maximum voltage of the normal battery.

Apparatus and method for detecting memory effect in nickel cadmium

The invention provides for a timesaving method of determining the capacity of a nickel cadmium (NiCd). A fully charged NiCd battery under is subjected to a positive sloped current charge ramp and then a negative sloped current charge ramp while continuously monitoring the battery terminal voltage. The voltage is plotted and the maximum slope of the measured terminal voltage determines l.sub.gas. The value of I.sub.gas is compared to a temperature calibration curve to determine the capacity of the battery under test.

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Clifton, NJ, United States of America

Patrick M Rudai