CDDC 1)DeC - DTIC
-it CAMICDDC1)DeCAlkaline Battery Divisioi JL.&LGULTON INDUSTRIES, INC.Metuchen, N. J.'.
STATE OF CHARGE INDICATORSFORNICKEL CADMIIUM BATTRIESTECHNICAL DOCUMENTARY REPORTNO. ASD-TDR-63-191February, 1963Directorate of AeromechanicsAeronautical Systems DivisionAir Force Systems C-.mmandWright-Patterson Air Force Base, OhioProject No. 8173, Task No. 817304-15AY 2 4 1963TSIA A(Prepared under Contract No. AF &( 657)-8130(by the Gulton Industries, Inc., Metuchen, New Jersey;M. Lurie, H. N. Seiger, R, C, Shair, authors.)
NOTICESWhen Government drawings, specifications, or other data are used for anypurpose other than in connection with a definitely related Government procurement operation, the United States Government thereby incurs no responsibilitynor any obligation whatsoever; and the fact that the Government may haveformulated, furnished, or in any way supplied the said drawings, specifications,or other data, is not to be regarded by implication or otherwise as in anymanner licensing the holder or any other person or corporation, or conveyingany rights or permission to manufacture, use, or sell any patented inventionthat may in any way be related thereto.Qualified requesters may obtain copies of this report from the ArmedServices Technical Information Agency, (ASTIA), Arlington Hall Station,Arlington 12, Virginia.This report has been released to the Office of Technical Services, U.S.Department of Commerce, Washington 25, D.C., for sale to the general public.Copies of this report should not be returned to the Aeronautical SystemsDivision unless return is required by security considerations, contractualobligations, or notice on a specific document.
FOREWORDThis Final Technical Report was prepared by GultonIndustries, Inc., Metuchen, N. J., for the Aeronautical SystemsDivision, Wright-Patterson Air Force Base, Ohio, under ContractNo. AF 33 (657)-8130.Mr. J. E. Cooper and Mr. W. S. Bishopwere task engineers for the Aeronautical Systems Division. Wewish to acknowledge the helpful discussions held with them.The studies reported "over the complete contractperiod from January 1962 to January 1963.
ABSTRACTThe variations of several electrical properties ofnickel cadmium cells with state of charge were studied todetermine the suitability of any of these for measuring stateof charge. Three methods were originally proposed: measurements of ohmic resistance, microsecond transients and doublelayer capacitance. During the investigations two additionalparameters were measured, a. c. impedance and phase shift.Double layer capacitance and a. c. impedance andtransient behavior are not useful properties for determiningstate of charge.A phase shift system is described which when properlycalibrated predicted state of charge with an average deviationof 10%. Ohmic resistance measured under correct conditionsshowed a closer correlation to state of charge but is difficultto measure.PUBLICATION REVIEWThe publication of this report does not constituteapproval by the Air Force of the findings or conclusions containedherein. It is published for the exchange and stimulation of ideas.iii
TABLE OF CORTEUTS1.Introduction12.Analysis of Electrical Properties of Cells43.Double Layer Capacitance74.Transient Peak Height105.Impedance at Audio Frequencies116.Phase Shift137.Internal Resistance218.Conclusions and Recommendations28References30Appendix I.Operation of Breadboard State-of-ChargeIndicator31Appendix II.Calculation of Time and Current Dependence ofResistance of a Cell35Appendix III.Calculation of Resistance of Mercury Switch37iv
LIST OF TABLESPage1.Double Layer Capacitance, F, at Various Residual Capacities402.Impedance of 4 A-H Cells at Various States of Charge433.Predicted and Actual Residual Capacities for Batteries onManual Cycle444.Predicted and Actual Residual Capacities for Batteries onAutomatic Cycle485.Predicted and Actual Residual Capacities for Batteries onShelf Stand496.Predicted and Actual Residual Capacities for BatteriesCharged at Modified Constant Potential507.Predicted and Actual Residual Capacities for [0-35 Celland 4KO15 Battery518.Effective Resistance at Various States of Charge529.Predictions of Residual Capacity from Resistance54Resistance of Rotary Switch and Components5710.V
LIST OF TABLESpage1.Double Layer Capacitance, F, at Various Residual Capacities402.Impedance of 4 A-H Cells at Various States of Charge433.Predicted and Actual Residual Capacities for Batteries onManual Cycle444.Predicted and Actual Residual Capacities for Batteries onAutomatic Cycle485.Predicted and Actual Residual Capacities for Batteries onShelf Stand496.Predicted and Actual Residual Capacities for BatteriesCharged at Modified Constant Potential507.Predicted and Actual Residual Capacities for KO-35 Cell51and 4K(015 Battery8.Effective Resistance at Various States of Charge529.Predictions of Residual Capacity from Resistance54Resistance of Rotary Switch and Components5710.v
LIST OF FIGURESPage1. Equivalent Circuit for Nickel Cadmium Cell582.Equivalent Circuit for Half-Cell593.Circuit for Demonstrating Transient604.Initial Transient, 4 A-H Cell615.Mechanical Switch for Pulse Measurements626.Schematic for Electronic Switch637.Variation of Double Layer Capacitance with Residual64Capacity8.Variation of Double Layer Capacitance with Residual65Capacity9.Tiansient Peak Height at Various Residual Capacities6610.Transient Peak Height for Two Cycles on Three Cells6711.A.C. Kelvin Double Bridge6812.Impedance Vs. Frequency for 4 A-H Cells6913.100 cps. Impedance at Various States of Charge7014.Apparatus for Measuring Resonant Frequency7115.Apparatus for Measuring Phase Shift at 60 cps7216.Diagram of Phase Measuring System7317.Resonant Frequency Vs. Residual Capacity7418.Resonant Frequency Vs. Residual Capacity7519.Phase Shift at Several Frequencies Vs. Residual76Capacity20.40 Cycle Phase Shift Vs.Residual Capacityvi77
LIST OF FIGURES (Cont'd)Page21.Calibration Curve at Room Temperature7822.Calibration Curves at Fixed Temperatures8223.Calibration Curve Showing Extreme Points8324.Distribution of Deviation, Histogram8425.Mechanical High Current Switch8526.Wiring Diagram of Mechanical Switch8627.Oscilloscope Display to Measure Resistance During.High Current Pulse8728.Effective Resistance Vs.8829.Four Methods of Connecting Voltage Leads to a Cell8930.Average Curve of RO Vs. R. C.9031.Resistance of Cell Permanently Connected to Apparatus9132.Design of Ultra-Low Resistance Switch9233.Block Diagram of Breadboard State of Charge Meter9334.Layout of Breadboard State of Charge Meter9435.Schematic of 40 Cycle Power Amplifier95Current and Timevii
ABBREVIATIONS USED IN sCycles per SecondEElectromotive ForcefFrequency in Cycles per SecondFkagnitude of double layer capacitance script indicates patticularresistorRCResidual capacity,wAngular frequencyvVVoltageZImpedanceviiiin Ampere-Hours 27rf
1. INTRODUCTIONThe purpose of the work reported here has been to investigate several proposed methods of measuring state of.charge of Ni-Cdbatteries. These investigations were to lead to a breadboard stateof-charge indicator. This report covers the contract period fromcommencement in February 1962 to January 1963. The required breadboard design has been completed and preliminary evaluation tests showthat the device can predict the remaining capacity in batteriesthat have been used recently as well as batteries that have beenstored for some time. For favorable conditions, an average errorof 10% has been consistently obtained.There have been several previous efforts to find a methodfor measuring state of charge of Ni-Cd batteries.Recent effortshave included studies of (i) dyes, (ii) charge and discharge characteristics and (iii)impedance at audio frequencies by Fleischer, (1)and (iv) a very extensive study of charge-discharge tests by Kordeschand Kornfeil.(2)Fleischer concluded that none of the techniques hestudied were acceptable state-of-charge indicators.Kordesch andKornfeil devised a means of measuring the polarization resulting fromcharge or discharge without the effect of the internal ohmic resistanceof the cell.Kordesch incorporated this technique into a batterytester based on charge-discharge characteristics.(3)Prototypes ofthis tester were built by the Vitro Corporation and were put throughextensive tests by Gulton Industries under contract to the SignalCorps (Contract No. DA 36-039 SC-85066).The conclusion reached atthe end of thos tests was that the device was not an acceptablebattery tester.Z4To be acceptable, a device would generally haveto:1)2)Have an accuracy of 5% (although a larger errormight stillprove very useful).Not discharge the battery appreciably during themeasurement.3)Give a reading independent of cell history.4)Be operable by an unskilled person and not requiremore than a few minutes for a measurement.Since the simplest access to a cell and the only accessto a sealed cell is via the terminals, it would be most desirable tofind some electrical property of a cell, one that could be measuredat the terminals, that depends on state of charge. For this reasoa,Manuscript released by the authors January 1963 for publicationas an ASD Technical Documentary Report.
1.INTRODUCTIONThe purpose of the work reported here has been to investigate several proposed methods of measuring state of charge of Ni-Cdbatteries.These investigations were to lead to a breadboard stateof-charge indicator.This report covers the contract period fromcommencement in February 1962 to January 1963.The required breadboard design has been completed and preliminary evaluation tests showthat the device can predict the remaining capacity in batteriesthat have been used recently as well as batteries that have beenstored for some time. For favorable conditions, an average errorof 10% has been consistently obtained.There have been several previous efforts to find a methodfor measuring state of charge of Ni-Cd batteries.Recent effortshave included studies of (i) dyes, (ii)charge and discharge characteristics and (iii)impedance at audio frequencies by Fleischer, (1)and (iv) a very extensive study of charge-discharge tests by Kordeschand Kornfeil.(Z)Fleischer concluded that none of the techniques hestudied were acceptable state-of-charge indicators.Kordesch andKornfeil devised a means of measuring the polarization resulting fromcharge or discharge without the effect of the internal ohmic resistanceof the cell. Kordesch incorporated this technique into a batterytester based on charge-discharge characteristics. (3)Prototypes ofthis tester were built by the Vitro Corporation and were put throughextensive tests by Gulton Industries under contract to the SignalCorps (Contract No. DA 36-039 SC-85066).The conclusion reached atthe end of thos tests was that the device was not an acceptablebattery tester.(4j To be acceptable, a device would generally haveto:1) Have an accuracy of 5% (although a larger errormight stillprove very useful).2)Not discharge the battery appreciably during themeasurement.3)Give a reading independent of cell history.4)Be operable by an unskilled person and not requiremore than a few minutes for a measurement.Since the simplest access to a cell and the only accessto a sealed cell is via the terminals, it would be most desirable tofind some electrical property of a cell, one that could be measuredat the terminals, that depends on state of charge.For this reason,Manuscript released by the authors January 1963 for publicationas an ASD Technical Documentary Report.
the approach used in this work was to study those electrical characteristics of cells that were shown to vary with state of charge. Manysuch properties were found, but for reasons involving their measurability,consistency and form of variation, most of these properties were unsuitable.Many electrical characteristics are appreciably differentfor fully charged and discharged cells, but remain nearly constant asa cell is discharged from 100% to 20% of capacity, most of the changeoccurring abruptly between 20% c arge and complete discharge.Two ofthe properties studied were found to vary with state of charge in sucha way that useful information could be obtained.These were the phaseshift and ohmic resistance to be discussed in Sections 6 and 7.The work was divided, logically and chronologically, intothree general phases:1)Observe any properties that vary with state of charge.2)Devise equipment to measure these properties.3)Using 2, examine the variation closely,particular,noting ina)How small a change in state of charge isdetectableb)How consistent is the variation?to cell? Cycle to cycle?Following this approach,From cellfive properties of cells werestudied carefully:1)Phase shift of cell voltage compared to current2)Internal resistance during a short,pulse3)Double layer capacitance4)Height of transient following a sudden changein current.5)Impedance at audio frequencieshigh currentThe last three were eliminated after experiments showed that theseproperties did not depend of state of charge in a consistent, usefulmanner.Detailed studies of the Birst two properties account forthe largest part of the exploratory phase of this wark. The variationof phase shift was first observed while the impedance was beingmeasured.Its dependence on state of charge was then establishedempirically.2
Although the term "state of charge" is videly used inbattery literature, the residusl capacity -. the actual number ofampere.bours available from the battery at a particular time -. isa more useful number because it san be measured directly by simplydischarging the battery. In this report the results of measurementsand predietions of battery condition are given as residual capacityIn ampere-hours. Because the term occurs so frequently, the authorshave taken the liberty of using the abbreviation RC.-3-
2.ANALYSIS OF ELECTRICAL PROPERTIESA brief theoretical discussion of the electricalprcperties of Ni-Cd cells is now given to show the relation of thevarious properties studied.The electrical model shown in Figure 1has a sine and transient response close to that of a cell and, therefore, is a good heuristic device for providing an understanding ofcell properties.The circuit of Figure I can be arrived at on purely physical grounds by considering the half-cell in Figure 2.Let there bea current flowing into the negative terminal and through the electrolyte to some other electrode.The current first encounters resistanceand inductance due to the terminal hardware and electrode material.Next the current sees a rise in potential between the electrode andthe main body of the electrolyte.In the electrolyte, the currentencounters more resistance. There is a capacitance between the electrode and the layer of charged ions in the electrolyte near the electrode.This is the double layer capacitance.The dashed line parallelto the electrode in Figure 2 indicates the effective position of the layer,though it is really diffuse. The double layer can be considered as acapacitance with one end connected to the electrode and the other endsomewhere in the electrolyte.Following the discussion above, thehalf-cell equivalent circuit in Figure 2 (a) was drawn.In the samemanner, a mirror image circuit can be obtained for a positive electrode in the same electrolyte.These will connect as in Figure 2(b).Combining all similar series elements, e.g. adding all series resistorsto form one larger resistor, yields the circuit in Figure 2 (c).Ifthe time constants of the two RC sections are nearly the same, thesecan be combined into one RC section yielding the equivalent circuitin Figure 1. The resonant frequencies of the positive and negativeelectrodes compared to an Hg/HgO reference were measured and found tobe of the same magnitude so this is a satisfactory approximation.Certainly the above discussion is descriptive, not rigorous.Its justification and utility lies in its ability to explain thesinusoidal and transient properties of a cell.The element valuescan be found from high and low audio frequency measurement.For aV04 nickel-cadmium cell, these values are, approximately,L10-6 H-R-10-3 OhmsR-10-3 OhmsC-lOFE1.3 V.-Using these values, the approximate resonant frequencycan be predicted.4
The impdanee of the equivalent ciremit is givem bytZ"(1)RL *,W.L '"0 C epareting reel anA Imginary parts222CL/2Z2L2RC 2D L]2For resonane, the imaginary part of Z is zero, soRe2 L 'CR2(WCu2 Lje -RcB 2CA-L(3)W0 2(4)4L221Resonant frequency, f(5)Substituting the orders of magnitude given for the components above,T10-6"R:5-50 cpsAotual resonant frequencies for 4 A-H oells were measured from60 to l 0 cps. Clearly this Is vithin the accuracy of the order ofmagnitude calculation.5(6)
The transient behavior observed when a cell is shortcircuited can also be predicted from this circuit. The actual calculations are lengthly and not relevant in this report so the resultwill be given without derivation. The current, I, when a cell isshort circuited is given by,-bt)I EW RLRc(1- e -(7)Figure 3 is a schematic representation of the variousswitch circuits used to measure cell transients. When S is open,the oscilloscope sees the open circuit cell voltage. When S isclosed, the current I rises according to the equation above. Thevoltage displayed is I%, whete N is the resistance of the switchwhen it is closed. After S is closed this voltage drops to zerothen rises exponentially as I rises. The voltage does not riseto the open circuit voltage because of the drop across R and Rand polarization. This is just the transient behavior observed inFigure 4.The state-of-charge dependence of the five electricalproperties mentioned in the Introduction will now be discussed indetail.6
At any solid-liqu d interfaeo theexists a doublecharged layer. On the solid, the electrode in our easethe chargeIs gotten either by absorption or Ionization. Ions of oppositecharge are distributed nar the electrode and are bold there byan electrostatic attraction. The layer of charp in the solutionis not diserete, but is diffuse. By a&usming that there is aplane representing the locus of the charges in this diffuse layrthe double layer Is "on. fince the electrodes vith vhieh we aredealing are flat plate@ the capacitance per unit area is given by:(8)CkIn sintered plate nickel-cadmium cells this capacitance is verylarge, in the order of 10 Farads for a V04 call.The voltage across the double layer is given by:(9)7kVso that one my vrite the vell-knovn equation,V U-0C(10)Multiplying the surface charge and the capacitance per unit areaby the total surface area and differentiating, one obtains,Idv/dt(11)This equation vas the basis for measurement of the double layercapacitance in these experiments. A know discharge curreat waspassed through the cell and the time rate of change of voltagevas measured. Because F is very large this slope Is sm ll evenfor large currents. Furthermore, the time interval during whichthe slope can be weasuredisfixed at about 3 nilliseconds becauseth measurement must be made after the transient has decayed andbefore polarization sets in further depressing the voltage.7
J MCZMThe voltage desay and current were measured simultaneouslyA resistiveLoad wsplaced aeroes a cell by seas of a switch and the easuing current andvoltee decay vere photographed with an oscilloscope camera. Todetermine I from the osaillogrpa, the aero current level had to berecorded as well as the ourrent after the resistor was connectedacross the cell. This was accomplished by triggering the oscilloscopebefore the switch was closed. The switch shown in Figure 5 was f rstused for this measurement. The small spring contact triggered theusing a Tektroaix 5M dual beam oseilloseope.oscilloscope before the main contacts closed. Thus, the short traebefore the current flowed indicated the zero current
commencement in February 1962 to January 1963. The required bread-board design has been completed and preliminary evaluation tests show that the device can predict the remaining capacity in batteries that have been used recently as well as batteries that have been stored for some time.
Council for Interior Design Accreditation Council on Academic Accreditation in Audiology and Speech-Language Pathology National Accrediting Agency for Clinical Laboratory . Dec 2 Dec 1 Nov 30 Classes resume Dec 13 Dec 12 Dec 15 Last day of classes Dec 14 Dec 13 Dec 19 Reading day Dec 14 Dec 13 Dec 19 Commencement Dec 16-20 Dec 15-19 Dec 16-18 .
developing country status Region Trend coefficient Trend p-value Cycle coefficient Cycle p-value CDDC East Asia and Pacific 0.48 0.00 0.23 0.09 CDDC Latin America and the Caribbean . support for research and development and the pro-vision of longterm patient capital (Anzolin and Lebdioui, 2021, p. 388). Furthermore, while the emergence of new .
Spencer’s opening hours over the Christmas period. Marks and Spencer Shopping Hours Monday 20th Dec 08.00 - 20.00 Tuesday 21st Dec 08.00 - 20.00 Wednesday 22nd Dec08.00 - 21.00 Thursday 23rd Dec 07.00 - 21.00 Friday 24th Dec 07.00 - 17.00 Saturday 25th Dec CLOSED Sunday 26th Dec CLOSED Monday 27th Dec 07.00 - 20.00 Tuesday 28th Dec 08.00 - 20.00
QRP Fox Hunt 0200Z-0330Z, Dec 9 NCCC Sprint 0230Z-0300Z, Dec 9 ARRL 10-Meter Contest 0000Z, Dec 10 to 2400Z, Dec 11 SKCC Weekend Sprintathon 1200Z, Dec 10 to 2400Z, Dec 11 International Naval Contest 1600Z, Dec 10 ***** to 1559Z, Dec 11 AWA Bruce Kelley 1929
Indicative Year- Import Embargo 25. Water Jet Fast Attack Craft Dec 2020 26. Ammunition Barges Dec 2020 27. 50 ton Bollard - Pull Tugs Dec 2020 28. Survey Vessels Dec 2020 29. Floating Dock Dec 2020 30. Diving Support Vessels Dec 2020 31. Pollution Control Vessels Dec 2020 32. Anti -Submarine Rocket Launchers Dec 2020 33.
Dec 7 - 11 - HA Halbert’s Virtual Book Fair Dec 10 - Rising Chefs (4:15 PM) Dec 11 - Hot Chocolate Day (Weather permitting) Dec 15 - Grade 1 - 6 Virtual BINGO @ 4:15 PM **NEW DATE Dec 16 - SAC Parent Council Meeting @ 6 PM Dec 17 - Virtual Halbert Family Sing-A-Long @ 6 PM Dec 18 - Student Recognition Assembly (P1/2)
Cluett House—A home for young working women. Miss Charlotte Teggart, Manager; Phone 2924. HAWAII . Dec. 23—Alfred Tsu Kong Tyau. Dec. 23—Homer Feng Kong Kau. Dec. 30—David Yin Fo Chong. Epiphany, Kaimuki. . Dec. 30—Roselyn Hyuk Lyam Wong. Dec. 30—Dorothy Ah Lui Chow. Dec. 30—Paul Fong. Dec. 30—Elsie Yee. St. Mark's Mission .
his greatest prestige and popularity with his novel Ariadne, in . identifies with Dorinda’s midlife awakening because she has been through that experience herself: after spending her life trying to live up to the standards of supportive wife, loving mother and perfect hostess that her husband’s elitist circle expected of her, “being my own person only became possible as an idea or a .
