CA2116910A1 - State of charge indicator for deep-cycle applications - Google Patents
State of charge indicator for deep-cycle applicationsInfo
- Publication number
- CA2116910A1 CA2116910A1 CA002116910A CA2116910A CA2116910A1 CA 2116910 A1 CA2116910 A1 CA 2116910A1 CA 002116910 A CA002116910 A CA 002116910A CA 2116910 A CA2116910 A CA 2116910A CA 2116910 A1 CA2116910 A1 CA 2116910A1
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- state
- monitor
- coupled
- charge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16542—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies for batteries
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/3644—Constructional arrangements
- G01R31/3646—Constructional arrangements for indicating electrical conditions or variables, e.g. visual or audible indicators
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S320/00—Electricity: battery or capacitor charging or discharging
- Y10S320/18—Indicator or display
- Y10S320/21—State of charge of battery
Abstract
STATE OF CHARGE INDICATOR FOR DEEP-CYCLE APPLICATIONS A state of charge indicator (10) monitors a voltage produced by a depletable energy source (11) and provides an indication when the state of charge of the depletable energy source (11) falls below a predetermined threshold. The state of charge indicator (10) includes an input circuit (13) for sensing the voltage and producing a plurality of tap voltages. The state of charge indicator (10) further includes a monitor circuit (65) for comparing each tap voltage with a corresponding threshold voltage and producing a result for each tap voltage falling below its corresponding threshold. The state of charge indicator (10) still further includes a storage device (75, 95, 115) for storing each result and producing an accumulated status and an output circuit (152) for producing the indication when the accumulated status exceeds an accumulated status threshold.
Description
TAl~B OF CHAR~3B INDICAq!O~ ~OR DEEP-QYCI,% APP~ICA'rXC)NE~
~,~
,j~ BACKGROUND QF THE INVENTION
~:~ The present invention generally relates to a state of charge indicator for providi.ng an indication when the ~tate of charge of a depl~table energy source ~alls below a predetermined threshcld. The present invention i~ more ~`~ particularly directed to a state o~ charge indicator ~or ,~` monitoring a voltage produced by ~ battery used in a de~p cycle application and producing an indication when the state of charge o~ the battery ~alls below a predetermined ~:~ lO threshold.
The state of charge of a depletable energy source such ~s~ as a battery is an indication sf the r~lative amoun of useable energy remaining in the battery. The stake oP
charge is given as a percentage eq~al to the ratio of the present amount of useable ensrgy remaining in the batt~ry ~: to the amount of useable energy in the battery when it is fully charqed. Thus, a fully-charged batt~ry ha~ a 100%
state of charge, a fully-discharged battery has a 0% stat~
of charge, and a battery charged to a level equal to one-~-~ 20 half i~s ~ull state o~ charge ha a 50% stat~ o~ charge.
Batteries are often used in deep cycle application~ to provide electrical energy to power electrical devices such as electric motors or emergency lighting. In deep cycle applications, batteries are routinely and repetitively discharged to a relatively low state of charge and ; recharged to a near 100% stat~ of charge. In othex ~ ~ applications, batteries such as starting batteries in '-~ automobiles, for example, are used only intermitt~ntly, to supply electrical energy to the starter mc)tor o~ the ~` 30 automobile. Aside from these momentary int2rmittent ~'. usages, such batteries are generally main~ained n~ar 100%
~: state o~ charge. Deep cyc:le applications, in contrast, routinely dischaxge ~he batt2ry to a low tate of charge during normal u~age.
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~: 2 -,~ Typical deep cycle application~ ~o~ a battery include providing power to an electric trolling motor in a fi~hing boat, providing power to the electric drive system o~ a . battery-operated wheelchair, or emsrgency powPr for securi~y system~. In such application~, the battery may be required to supply current for ~everal hours. Supplying . .
,ii~ this current will di~charge the battery to a relatively low ~: state o~ charge. Later, the battery may be rechargPd to a !.`. ~ nearly 100% state of charge. This same cycle o~
~ 10 discharging and recharging t:he battery may be repeated ~any .i times over the life of the battery.
In view o~ these typical applications, it would be advantageous to provide a battery with a 5tat~ o~ charge .~;............... indicator. Such an indicator would provide a visible or i~ 15 audible i~dication when the 8tate of charge of the battery has ~allen below a predetermined threshold. The i~dication would inform a u~er of the low ~tate of charge condition , and the impending need to recharge the b~ttery. The ; indication reduces the risk of discharging the battery to . 20 a level insufficient to provide usable power or to a level at which irreversible damage to the battery may occurO
There i8 a need for a state of chaxge indicator ~or deep cycle applications which can provide a timely indication o~ a low state of charg~ condition when the battery is subjected to a wide range of load currents.
There is also a need for a iow state of charge indicator which is not sensitive to voltage fluctuations which might cause the state o~ charge indication to fluctuate about the low state of charge set point. The state o~ charge indicator may provide, Por exa~ple, an indication when th~ battery state o~ charge ~alls below a set point of 50% ~tate o~ charge. As the ~tate of charge of the battery ~alls below thi~ set point~ a ~ransient in the ourrent supplied by the battery may caus~ the voltage supplied by the battery to ~alsely indicate a state oP
charge above the set point. Accordingly, there is a need for a state of charge indicator which latches the low state of charge indication and does not reset the latched ~` 2~16~10 ~- conditio~ until the battery has be~n recharged to well above the state of charge setpo:Lnt level.
~; In general, the state of charge indicator of ~he ~ present invention measures battery voltage and compares the -~ 5 battery voltage to different pr~set voltage values at corresponding specified time intervals and evaluates if the battery voltage is above or below the preset voltage values. The preset volt:age value~ and corresponding :~ specified time intervals are empirically determined for a : 10 given type of battery and ~;tate o~ charge setpoint lev~10 The results of the evaluations are placed into, for example, shi~t registers. The number o~ low indications within the shift registers are summed and evaluated. If the sum exceeds a predetermined accumulated status threshold, an output indication is provided, indicating a low s~ate o~ charge conditionO I~ the low state of charge indication is provided, this o~tput indication is latched until the state o~ charge indicator detects that the battery has been rec~arged to well above the predetermined state of char~e setpoint level.
SUM~ARY OF THE INVEN~ION
~ The prasent invention provides a state o~ charge ?~ indicator Por monitoring the voltage o~ a depletable energy '~ source and providing an indication when the s~ate o~ charge ~ 25 of the depletable energy source falls below a predetermined :~; threshold level. The state o~ charge i~dicator includes an input system for sensing the voltag~ of the depletable energy source and providing a signal to a monitor system co~prising several stages. Each stage of the monitor sy~tem compare~ the sensed voltage signal to the ~: corresponding threshold voltage for that stage. Each stage ~urthsr compri~es a storage syste~ for storing the result ~; of the comparison at regular tim~ interval~ ~or that stage9 The storage system stores a finite number of results representing the short term history of compari~ons for that stage. Th2 ~tate of charge indicator urther includes an ~; output system coupled to the ~ orage system of all individual stages. The stored results of all th~ stages ~;, ~`
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: are ~ummed to produce an accumulat2d ~tatus. The output system produces the indication when the accumulated status : exceeds the accumulated status threshold. The state of , . . .
f: charge indicator further provides a recharge monitor systam coupled to the input system for determining iP the depletab1e power source has been recharged. The output ~ system continues to produce the indication until the ;~ accumulated status no longer exce~d~ the accumulated statuR. threshold and the recharge monitor system indicates ~hat : 10 the depletable energy sourc~ has been recharged.
The present invention provides a state of charge ii indicator for monitoring a voltage produced by a depletablei energy source and providing an indication when the state o~~i: charge oP the depletable energy source ~alls below a f 15 predetermined thresholdO The ~tate o~ charge indicator '~ includes input system for sensing the voltage and producinga plurality of tap voltages and monitor ~ystem coupled to the input system for comparing each tap voltag~ with a corresponding threshold voltage and producing a result ~or each tap voltage ~alling below its corresponding threshold ~ voltage. The state of charge indicator still further f'~ includes storage system for storing each result at -~ corresponding time intervals and producing an accumulated status and output system coupled to the storage syste~ ~or ~,J-~i 25 producing the indication in response to the accumulated status exceeding an accu~ulated ~tatus threshold.
In accordanc2 with the present invention, the input system of the state o~ charge indicator may further produce a recharge tap voltage. The state o~ charge indicator o~
the present invention may further comprise recharge monitor system for forcing the output system to continue providing `i~ the indication when the accumulated status no longer :.' exceeds the accumulated status thre~hold and when th~
. recharge tap voltage remains below a recharge threshold.
The present invention fur~her provides a state of charge indicator for providing an indication when the state of charge of a battery falls below a predetermined threshold levPl. The state o~ charge indicator includes ..~.
,' ' 1..1.&~10 i :
: - 5 -input system for sensing a volta~ produced by the battery ;:~ and producing a plurality of tap voltages and a plurality of monitor stages coupled to the input system and havin~ a common output. Each monito:r stage includes sensinq system ~: 5 for sensing one tap voltage oP the plurality o~ tap i;~ voltages and producing a result when the one tap voltage ~; falls below a predetermined threshold. Each monitor stage further includes storage system coupled to the sensing ~,~ system for storing each result at correspondiny time ~ 10 intervals, the storage system having an output coupled to ,,~ the common output for supplying an accumulated status. The state of charge indicator further includes comparator system coupled to th~ common output ~or prodllcing a signal when the accumulated statu3 exceeds a predetermined accumulated status threshold and output system coupled to ~ the comparatQr system for providing the indication in '~; response to the signal.
~ Th~ present invention still further provides a method !~''' of monitoring a voltage produced by a depleta~le energy source and producing an indication when the state of charge of th2 depletable energy sourc~ ~alls below a predetermined threshold. The method includes the steps of sensiny the voltage and producing a plurality of tap voltages, comparing each tap voltage to a corresponding threshold voltage and producing a result ~or each tap voltage falling below i~ corri3ponding threshold volt~ga, producing an accumulated statUs of the result5, and providing the indication when the accumulated status exceeds an ~` accumulated status threshold.
BRIE~ DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are set forth with particularity in . the appended claims. The invention, together with ~urther ob j ects and advantages thereof, may best be understood by making reference to the following des::ription takerl in conjunction with the accompanying drawing, in the sole - ~igure oi which identical re~erence characters indicate . ~: is1entical elem~nts, and wheri~in the ssle ~igure is a ~ ,:
~ 3 ~
,;
,. - 6 -: schematic diagram illustrating the manner in which the present invention may be implemented ln hardware form in accordance with the preferred embodiment of the present . invention.
..
~ 5 DE~ IPTION OF THE_PREFERRED EMBODI~ENT
;~ Re~erring now to the sole figure, it illustrates a state of charge indicator 10 embodying the present ~i invention. The state of charge indicator 10 is oE the type ~` which monitors a voltage produced by a depletable energy ~:: 10 source such as a battery 11 and provides an indication when the state o~ charge of the depletable ener~y source ~alls below a predetermined threshold.
The stat~ o~ charge indicator 10 generally includes input system 13, a threshold generating syste~ 46, monitor sy tem 65, comparator system 134 and output system 152.
The monitor system 65 may include one or more monitor stages such as first monitor stage ~6, second monitor stage 68 and third monitor stag~ 70. The state of charge indicator 10 also includes recharge monitor system 168 and clock system 178.
The input system 13 o~ the state of r:harge indica~or 10 includes a positive input 12, a negative input 14, and resistors 1 , 24, 30, 36, and 42. The positive input 12 and the negative input 14 are preferably coupled to the terminals of the depletable energy source 11. The negative input 14 preferably ~orms or provides system ground. The positive input 12 is coupled to the first end 16 of re~istor 13. The second end 20 of the resistor 18 is coupled to the first end 22 of resistor 24. The second end 26 of the resistor 24 i~ coupled to the first end 28 o~
resistor 30. The second end 32 of the resistor 30 is coupled to the first end 34 of resistor 3~. The second end 3~ of the resi~tor 36 is coupled to the ~irst end 40 o~
resistor 42. The second end 44 of resistor 42 is coupled to the negative i~put 14. Resistor 18, resistor 24, resistor 30, resistor 36, and re8istor 42 form input system i~ 13 Por sensi~g the voltag~ between the positiv~ input 12 ,~, !
~`',~'' ~;
and the negative input 14 and producing a plurality of tap voltages.
Also coupled to the positive input 12 i5 the threshold generating system 46. The threshold generating system 46 includes a diode 48, a resistor 52, zener diodes 50, 60 and 62, and capacitor 58. The anode of the diode 48 i5 coupled ~ to the positive input 12. The cathode of the diode 48 is 5~;~ coupled to the cathode o~ the zener diode 50 ~nd a first end 53 o~ the resistor 52. ~he anode of the zener diode 50 ~`~ 10 i~ coupled to the negative input 14. The second end 56 of ~-~ the rasistor 52 is coupled to a vcr node 54. The VCC node .~ 54 is preferably provided with a voltage of +5 volts and ~; provides positive supply voltage to other components of the state of charge indicator lo. The capacitor 58 is ~oupled between the second end 56 o~ the resistor 52 and the negative input 14. The cathode of the zener diode 60 is coupled to the ~econd end 56 o~ the resistor 52. The anode ~; o~ the zener diods 60 is coupled to a re~rence node 64.
The cathod~ of the zener diode 62 i~ coupled to the ~s 20 reerence node 64. The anode of the z~ner diode 62 i5 coupled to the negative input 14.
In the operation of the threshold generating syst8m 46, a reference voltage is provid~d at the re~erence node 64. This reference voltage iB preferably temperature and current compensated as is well-kno~n in the art. This . reference voltage is used ~or producing threshold voltages corresponding to each tap voltage produced by th~ input system 130 The ref rence node 64 is coupled to monitor system ~5.
The monitor syste~ 65 includes first, second and third monitor stages 66~ 68 and 70.
The ~irst monitor qtage 66 includes monitor syste~ 74 ~` and storag~ syste~ 75. The storage system 75 includes shift register 82 and resistor~ 88a, 88b, 88c, 88d, 88e, ~: 35 88f, 88g, and 88h. In the first ~onitor ~age 66, ~
~; re~istor 72 is coupled betwPen the re~erence node 64 and the monitor system 74. The monitor system 74 includes an operational ampli~ier 76 and a ~eedback resistor 78. The "~
'~
::
,. i . ..
211~910 ~;~
output of th~ monitor system 74 is coupled to an input 80 of shift register 82. The shift register 82 also has a ~-: clock i~put 84. The shift register 82 furth~r has outputs 86a, 86b, 86c, 86d, 86e, 86f, 86g, and 86h coupled to resistors 88a, 88b, 88c, 88d, 88e, 88f, 88g, and 88h, rsspectively, which have a common connection to form an output 90 of the first monitor stage 66.
The second monitor stage 68 include~ monitor system 94 and storage system 95. The storage sy~tem 95 include~
shift register 102 and resi~tor~ 108a, 108b, 108c, 108d, 108e, 108f, 108g, and 108~l. In the second monitor stage 68, a resistor g2 i~ coupled between the reference node 64 and the monitor system 94. The monitor syst~m 94 include~
an operational amplifier 96 and a ~eedback resistor 98.
The output of the monitor system 94 is coupled to an input 100 of the shift register 102. The shift register 102 also has a clock input 104. The shi~t register 102 has outputs 06a, 106b, 106c, 106d, 106e, 106f, 106g, and 106h coupled to resistors 108a, 108b, 108c, 108d, 108e, 108~, 108g, and lOSh, respectively, which have a co~mon connection to form ~' an output 110 of the second monitor stage ~8.
The third monitor stage 70 includes monitor ~ystem 11 and storage system 115. The storage system 115 include~
shift register 122 and resistors 128a, 128b, 128c, 128d, . ~ 25 128e, 128f, 128g, and 128h. In the third monitor stage 70, . ~ a resistor 112 is coupled between th~ reference node 64 and the monitor sy~tem 114. The monitor system 114 includes an operational amplifier 116 and a fe~dback resistor 118. The output of the monitor system 114 is coupled to an input 120 . 30 of a shift register 122. The shift regi~ter 122 al~o h~s ;~ a clock input 124. The shift register 12~ has outputs . 126a, 126b, 126c, 126d, 126e, 126f, ~26gt and 126h coupled to resistors 128a, 128b, 128c, 128d, 128e, 128f, 128g, and 128h, respectively, which have a common connection to form an output 130 of the third monitor stag2 70.
.
~ The output 90 of the first mon1tor stage 6S, th~
" c~utput 110 of the ~cond monitor ~tage 68 and the output 130 of t:he third monitor stage 70 ar~ coupled together to ~, , ~' 21 1 ~91~
j .
~.,, ~ g . .. ~.
form a common output 132. The common output 132 is coupled to the comparator system 134. The comparator system 134 includes a resistor 136, an operational amplifier 138, a feedback resistor 140 and 2 resistor 144. The inverting input of the operational amplifier 138 is coupled to the reference node 64. The operational ampli~ier 138 has an output 142 coupled to a fir~:t end 146 of the r2sistor 144.
The second end 148 of the resistor 144 is coupled to node 150.
Node 150 is also coupled to the output system 152.
The output system 152 include~ a latch system 154 and an output device 162. The latch system 154 includes an operational amplifier 156 and a feedback r2sistor 158. The output of the latch system 154 i5 coupled to a resistor 160. The resistor 160 is further coupled to the output device 162 whi~h may be a switchi~g device such as a field effec~ transistor. In the embodiment sho~n in the figure, th~ output device 162 is coupled to a light emitting diode 164. The anode o~ the light emitting diode 164 is coupled to a current limiting resistor 166. The re~istor 166 i~
Goupled to the positive input 12. ~hus, when the output system 152 provides an indication of low state of charge, light emitting diode 164 is illuminated. The low state of charge indication may be any visual, electrical, audible, or other signal capable of indicating the low state of charge condition to the user.
The state of charge indicator 10 also includes recharge monitor system 168. The first end 40 of resistor 42 o~ the input ~yste~ 13 is al50 c3upled to the recharge monitor system 168. The recharge monitor ~ystem 168 includes a resistor 170, an operational amplifier 172, a ~eedbac~ resistor 174 and a resistor 176. The inverting input of the operational amplifier 172 is coupled to the ,..
r~fsrence node 64. The reoharge monitor system 168 has an output 173 coupled to a ~irst end 175 of the resi~tor 176.
The second end 177 of the re~istor 176 is coupled to node ` 150.
.' .~
Lastly, the state of charge indicator 10 includes a clock system 178 for providi~g a plurality of clock ~: signals. Clock system 178 includes a resistor 180, a capacitor 182 and a clock generator lQ4. The clock generator 184 provides clock signals on outputs 186, 188, and 190. Output 186 is coupled to the clock input 84 of the shi~t register 82. Out:put 188 i~ coupled to the clock input 104 of the shift register 102. Output 190 is coupled to the clock input 124 of the shift register 122. The clock generator 184 generates alock signals at a rate determined by the values of resistor 180 and capacitor 182.
''. Preferably, the frequencies o~ clock signals provided on outputs 186, 188 and 190 are diffexent. Preferably the frequency of the clock siqnal provided on output 190 i8 lower than the frequency of the clock signal provided on output 188. Also, preferably the fre~uency of the clock slgnal provided on output 188 is lower than the frequency ~; of the clock signal provided on output 186.
a For monitoring a voltage produced by a depletable energy source and providing an indication when the state o~
ch~rge of the depletabl~ energy source falls below a predetermined threshold, positive input 12 ~nd negatiYe ~r~ input 14 are coupled to the output ter~inals of the depletable ener~y sour e. The resistors 18, 24, 30, 3~, . 25 and 42 form a voltage divider. The voltage divider produces tap voltages proportional to the voltage batween j positive input 12 and negative input 14. A first tap voltage is producediat the second end 20 o~ the resistor 18 ~i~ and supplied to the inverting input of the operational ` 30 amplifier 76 of the monitor system 74 of th first moni or stage 66~ The monitor syste~ 74 form~ a comparator with . hysteresis, well-known in the art~ The magnitude of the tap voltage supplied to the inverting input of the operational amplifier 76 is compared with a threshold voltage at the noninverting input of operational amplifier 76. When the tap voltage supplied to ~onitor system 74 is ~: greater than the threshold voltag~ supplied to the monitor ~. system 74, the output o~ the monitor system 74 will be a ;i,`~:
'~ :L 1~ O
,",~
.~` , '~. voltage corresponding to a logical 0 value. Wh~n the tap voltage supplied to khe monitor system 74 is l~ss than the threshold voltage supplied to the monitor ~ystem 74, as when the state oE charge of the depletable energy source coupled to positive input 12 and negative input 14 is *~ diminished in value, the output of the monitor ~ystem 74 ~: will be a voltage corresponding to a logical 1 value.
,.i~ The output produced by the monitor system 74 is supplied to the inpu~ 80 of the shift register 82. The shift register 82 prefPrably includes a plurality of storage locations, each storage location having an associated order, the order being from highest to lowest.
In response to a clock signal received at clock input 84, the shi~t register 82 discards th~ contents of the highest-ordered storaye location, sequentially moves the contents of each storage location to the next highest-ordered `~ ~tor~ge location, and stores the logical value supplied at : input 80 in the lowest ordered storage location.
-~ Preferably, shift register 82 inoludes eight such storage locations. The contents of each such storage location is ~;~ supplied to outputs 86a, 86b, 86c, 86d, 86e, 86f, 86g, and -`~` 86h, respectively. A voltage corresponding to the sum o~
the contents o~ the eight storage locations of the shit register 82 i~ ~up~lied to output 90 of first monitor stage ~, 25 66.
Thus, the first monitor stage 66 compares the tap ~:~ voltage at the second end 20 o~ the resistor 18 with a corre~ponding threshold voltage and produces a result.
Responsive to clock signals from the clock system 178, the ~: 30 ~irst monitor stage 66 stores the results o~ the eight preceding comparisons. The results of these comparisons are summed and a voltage corresponding to the sum is provided at th~ output 9 0 .
In a similar manner, thr second monitor stage 68 compares the tap voltaye at the second end 26 of the r~sistor 24 with a corresponding threshold voltage and produces a result. Responsive to clock signals from the ~3i!,; clock system 178, thP second monitor stage 68 stores the ..
j~
results of the eight preceding comparisons. The results of these comparisons are summed and a voltage corresponding to the sum is provided to the output llo.
In like manner, the third monitor stage 70 compares thP tap voltage at the second end 32 of the resistor 30 ~: with a corresponding threshold voltage and produce~ a resultO ResponsiYe to clock signals ~rom the clock system 178, the third monitor stage 70 ~tor~$ the re~ult~ o~ the eight preceding comparison~. The results o~ these comparisons are summed and ia voltage correspanding to the sum is provided to the output l.30.
As noted above, the clock signals provided at the outputs 186f 188 and l9o o:E the clock system 178 to the . first monitor stage 66, the second monitox stage 68, and the third monitor stage 70, respectlvely, preferably have dif~ering frequencies. Preferably, ~he clock signal provided to the first monitor stage 66 has a greater frequency than the clock signal provided to the ~econd ~; mo~itor stage ~8 and the clock signal provided to the second monitor stage 68 has a gr~ater ~requency than ~he cloc~ signal provided to the third monitor stage 70. Thus, ~'~ the first monitor stage 66, which co~pares the tap voltage . having the highest voltage magnitude which correspond~ to the threshold voltage having the lowest voltage magnitude, ~` 25 stores the results of the comparisons most frequently.
Si~ilarly, the third monitor stage 70, which compares the tap voltage having the lowest voltage magnitude which ~-` corresponds to the threshold voltags having the highest '~! YOltage magnitude, stores the results of the comparison '~ 30 least frequently.
~ During the discharge cy~le oP a battery, the battery ;~. voltage decreases as the battery state o~ charge decr~ases for a given discharge rate. Similarly, the voltage decreases as the rate of disGharge increases for a given ~tate of charge condition. Each stage compares the battery voltage to different threshold voltages at di~erent rates.
,~ A relatively low battery voltage can be attributed t~ two . conditions: the rate of dis~harge i5 high or the battery 9 1 ~
state of charge is low. Both of these condition6 necessitate that the sampling rate for the st~ge with the `~ lower threshold voltage be r~latively fast in order that ~ the battery monitor indicates bePore the battery state of ,~: 5 charge fall~ well below the predetermined state o~ charge ~;~ threshold. Conversely, a relatively high battery voltage indicates that the battery c;tate of charge is high or that j~. the discharge rate is low. These two conditionsnecessitate that the sample rate for the stage with the higher threshold voltage be relatively slow. In this ~` second scenario, there is plenty of timc to identi~y the low state of charge conditi~n before the battery state oP
~.~ charge falls below the predetermined state o~ charge j threshold. Through proper sel~ction of thre~hold voltage~
and storage rates, a given state of charye can be correctly identified ~or varying discharge conditions t~ a high level ~: of precision.
~; The embodiment of the present invention shown in the ~: drawing includes three monitor stayes, the first monitor stage 66, the second monitor stage 68, and the third ~:~ monitor stage 70. As will be appreciated by those skilled in the art, a dif~erent number of ~onitor stages may be utilized without departing from the present invention. The number of ta~es required is dependent upon the application for which the baktery coupled to the state of charge indicator ~0 is used. More monitor stages will be rPquired in application~ which have a broad current range, i.e., 3 current range from 0 to 150 amperes during use or in .
applications in which the current supplied by the battery 3G varies greatly, i.e., the current fluctuat~s during use ~rom 0 to 75 to 25 to 100 amperes. Also, the state of ; charge indicator will require more ~tages for applications : in which it is desirable to increase the accuracy of the .: state of charge indicator.
The clock ~requencie~ supplied by the clock system 178 -~ and the predetermined threshold voltages corresponding to each tap voltage are chosen based on known characteristic~
of the battery to which th~ ~tate of charge indicator 10 i8 7 1 1 ~ 9 10 ~ coupled. The frequencies and threshold voltages are also I ~ pre~erably cho5en so that state o~ charge indicator 10 will provide the state of charge indication at any predetermined level from 0% to 100% state o~ charge and to some level o~
precision, such as a 5% band about the predet~rmin2d state of charge level.
The comparator system 134 monitors the accumulated status produced at the common output 132 o~ the first r~ monitor stage 66, the secsnclmonitor ~tage 68 and the third monitor stage 70. The accumulated status i8 supplied ts ,.
.~ the noninverting input of the operational amplifier 138.
The re~erence voltage on the re~erence node 64 is supplied to the inverting input of the operational a~pli~ier 138.
When the voltage magnitude of the accumulated status is . 15 less than the voltage magnitude of the reference voltage at node ~4, the output of the operational amplifier 138 corresponds to a logical 0 value. This logical 0 value indicates that he state of charge indicator has not detected a low state o~ charge conditi~n. When the voltage magnitude of the accumulated status is greater than the re~erence voltage, the outpu~ of the operational amplifiex ~,. 13B will have a value corresponding to a logical 1 value.
This logical 1 value indicates that the state of charge `: indicator 10 has detected a low state of charge indication.
., The recharge monitor system 16~ monitors a recharge tap voltage produced at the second end 38 of the resistor :~ 36. The recharge tap voltage is supplied to the ~ noninverting input of the operational amplifier 172. The ,-~ reference voltage is supplied on the reference node 64 to ~: 30 the inverting input of operational amplifier 172. When the recharge tap voltage has a voltage magnitude greater than ~ the reference voltage supplied on the reference nod~ 64 the ;~ output of the operational ampli~i~r ~72 ha~ a logical 1 value. When the recharge tap voltage ha~ a voltage magnitude less than the re~erence voltage, ths output o~
the operational amplifier 172 has a logical 0 value. The logical 1 value at the output of the operational amplifier 172 indicates that the depletabl~ energy source coupled across the positive input l2 and the negative input 14 is charging or is ~ully charged. The logical 0 value at the output o~ the operational ampliPier 172 indicates that the ,~` depletable energy source i6 not charging or is not fully charged. The recharge monitor system 168 is used for forcing the output device 162 to continue providiny a low state o~ charge indication when the accumulated status no ~: longer exceeds the accumulated status threshold and when ~ the recharge tap voltage falls below the recharg '}`~ 10 threshold. Thus, the output of the operational amplifier ~- 172 provides a recharge signal.
An important aspect o~ thQ present invention i~
provided by the latch system l54. The latch system 154 ~orms an output control system for controlling the output device 162 in response to the comparator system 134 and the recharge monitor system 168. The operation of the latch ~: ~ystem 154 is shown in the truth table, Table I.
~; Previous Charging Accu~ulated ' Next Output ,~ Output 1156i 1172~ Statu~ (l38L I (l56L
.. 20 o o o I o .~' O 0 1 1 1 ,,"~ 1 0 0 }
~ 25 1 0 l j 1 i'.' 1 1 0 ' O
, ~ 1 1 1 ' 1 TABLE I
As will be noted ~rom Table I, the next output, the ~ 30 output of th~ operational amplifier 156, is a function of r, ~he previous output, which is the output of the operational amplifier 156, the recharge 6ignal, which i8 th~i output o~
the oparational ampli~'ier 172, and the accumulated status . which is the output of the operational amplifier 138~ When th~ next output has a logical 0 value, the output device ir~ 162 will not provide a low state of charge indication.
,',f~ Similarly, when the next output has a logical value 1, the ~ 21 1~10 ; 16 -,, output device 162 will provide 21 low state of charge indication.
~!~ As can thus be seen in Table I, the ~tate of the next . output generally tracks the state of the accumulated . 5 status. However, where the accumulated status is a O,indicating the battery does not presently have a low state o~ charge, and the charging output i5 a 0, indicating the , battery i8 not recharging or fully charged, and the previous output was a 1, indicatiny a low state o~ charge, the next output remains a :Logical l~ indicating low state ~v o~ charge. Thu~, the state o~ charge indicator 10 is .- rendered insensitive to short~term ~luctuations o2 the output voltage of the depletable energy source. Once the ~; state of charge indicator 10 ha~ detected a low state o~
;-~ 15 charge and provided an indication through the oukput device , 162, the low state of ¢harge state is latched by the latch system 154. The latch ~ystem 154 is only reset by a logical 1 on the charging output, the output o~ the operational amplifier 172 9 a,~ 20 From the ~oregoing, it can be seen that the present invention provides a new and improYed state of charge indicator for monitoring a voltage produced by a d2pletabl2 ~: energy scurce and providing an indication when the state of charge o~ the depletable energy sourc~ ~alls below a pr~determined threshold. In addition, ~he state of charge ~- indicator of th2 present invention assures that th~ low state of charge indication will continue to be provided until the depletable energy source has been recharged to well above the predetermined setpoint level.
.; 30 ~hile a particular embodiment of the present invention has been shown and described, modifications may be mad~, and it is therefore intended in th~ appended claim~ to cover all such changes and modificatlons which ~all within the true spirit and scope o~ th~ inYention.
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,j~ BACKGROUND QF THE INVENTION
~:~ The present invention generally relates to a state of charge indicator for providi.ng an indication when the ~tate of charge of a depl~table energy source ~alls below a predetermined threshcld. The present invention i~ more ~`~ particularly directed to a state o~ charge indicator ~or ,~` monitoring a voltage produced by ~ battery used in a de~p cycle application and producing an indication when the state of charge o~ the battery ~alls below a predetermined ~:~ lO threshold.
The state of charge of a depletable energy source such ~s~ as a battery is an indication sf the r~lative amoun of useable energy remaining in the battery. The stake oP
charge is given as a percentage eq~al to the ratio of the present amount of useable ensrgy remaining in the batt~ry ~: to the amount of useable energy in the battery when it is fully charqed. Thus, a fully-charged batt~ry ha~ a 100%
state of charge, a fully-discharged battery has a 0% stat~
of charge, and a battery charged to a level equal to one-~-~ 20 half i~s ~ull state o~ charge ha a 50% stat~ o~ charge.
Batteries are often used in deep cycle application~ to provide electrical energy to power electrical devices such as electric motors or emergency lighting. In deep cycle applications, batteries are routinely and repetitively discharged to a relatively low state of charge and ; recharged to a near 100% stat~ of charge. In othex ~ ~ applications, batteries such as starting batteries in '-~ automobiles, for example, are used only intermitt~ntly, to supply electrical energy to the starter mc)tor o~ the ~` 30 automobile. Aside from these momentary int2rmittent ~'. usages, such batteries are generally main~ained n~ar 100%
~: state o~ charge. Deep cyc:le applications, in contrast, routinely dischaxge ~he batt2ry to a low tate of charge during normal u~age.
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~ ` 2:~1691(3 i`
~: 2 -,~ Typical deep cycle application~ ~o~ a battery include providing power to an electric trolling motor in a fi~hing boat, providing power to the electric drive system o~ a . battery-operated wheelchair, or emsrgency powPr for securi~y system~. In such application~, the battery may be required to supply current for ~everal hours. Supplying . .
,ii~ this current will di~charge the battery to a relatively low ~: state o~ charge. Later, the battery may be rechargPd to a !.`. ~ nearly 100% state of charge. This same cycle o~
~ 10 discharging and recharging t:he battery may be repeated ~any .i times over the life of the battery.
In view o~ these typical applications, it would be advantageous to provide a battery with a 5tat~ o~ charge .~;............... indicator. Such an indicator would provide a visible or i~ 15 audible i~dication when the 8tate of charge of the battery has ~allen below a predetermined threshold. The i~dication would inform a u~er of the low ~tate of charge condition , and the impending need to recharge the b~ttery. The ; indication reduces the risk of discharging the battery to . 20 a level insufficient to provide usable power or to a level at which irreversible damage to the battery may occurO
There i8 a need for a state of chaxge indicator ~or deep cycle applications which can provide a timely indication o~ a low state of charg~ condition when the battery is subjected to a wide range of load currents.
There is also a need for a iow state of charge indicator which is not sensitive to voltage fluctuations which might cause the state o~ charge indication to fluctuate about the low state of charge set point. The state o~ charge indicator may provide, Por exa~ple, an indication when th~ battery state o~ charge ~alls below a set point of 50% ~tate o~ charge. As the ~tate of charge of the battery ~alls below thi~ set point~ a ~ransient in the ourrent supplied by the battery may caus~ the voltage supplied by the battery to ~alsely indicate a state oP
charge above the set point. Accordingly, there is a need for a state of charge indicator which latches the low state of charge indication and does not reset the latched ~` 2~16~10 ~- conditio~ until the battery has be~n recharged to well above the state of charge setpo:Lnt level.
~; In general, the state of charge indicator of ~he ~ present invention measures battery voltage and compares the -~ 5 battery voltage to different pr~set voltage values at corresponding specified time intervals and evaluates if the battery voltage is above or below the preset voltage values. The preset volt:age value~ and corresponding :~ specified time intervals are empirically determined for a : 10 given type of battery and ~;tate o~ charge setpoint lev~10 The results of the evaluations are placed into, for example, shi~t registers. The number o~ low indications within the shift registers are summed and evaluated. If the sum exceeds a predetermined accumulated status threshold, an output indication is provided, indicating a low s~ate o~ charge conditionO I~ the low state of charge indication is provided, this o~tput indication is latched until the state o~ charge indicator detects that the battery has been rec~arged to well above the predetermined state of char~e setpoint level.
SUM~ARY OF THE INVEN~ION
~ The prasent invention provides a state o~ charge ?~ indicator Por monitoring the voltage o~ a depletable energy '~ source and providing an indication when the s~ate o~ charge ~ 25 of the depletable energy source falls below a predetermined :~; threshold level. The state o~ charge i~dicator includes an input system for sensing the voltag~ of the depletable energy source and providing a signal to a monitor system co~prising several stages. Each stage of the monitor sy~tem compare~ the sensed voltage signal to the ~: corresponding threshold voltage for that stage. Each stage ~urthsr compri~es a storage syste~ for storing the result ~; of the comparison at regular tim~ interval~ ~or that stage9 The storage system stores a finite number of results representing the short term history of compari~ons for that stage. Th2 ~tate of charge indicator urther includes an ~; output system coupled to the ~ orage system of all individual stages. The stored results of all th~ stages ~;, ~`
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f:~ - 4 -i ~:
: are ~ummed to produce an accumulat2d ~tatus. The output system produces the indication when the accumulated status : exceeds the accumulated status threshold. The state of , . . .
f: charge indicator further provides a recharge monitor systam coupled to the input system for determining iP the depletab1e power source has been recharged. The output ~ system continues to produce the indication until the ;~ accumulated status no longer exce~d~ the accumulated statuR. threshold and the recharge monitor system indicates ~hat : 10 the depletable energy sourc~ has been recharged.
The present invention provides a state of charge ii indicator for monitoring a voltage produced by a depletablei energy source and providing an indication when the state o~~i: charge oP the depletable energy source ~alls below a f 15 predetermined thresholdO The ~tate o~ charge indicator '~ includes input system for sensing the voltage and producinga plurality of tap voltages and monitor ~ystem coupled to the input system for comparing each tap voltag~ with a corresponding threshold voltage and producing a result ~or each tap voltage ~alling below its corresponding threshold ~ voltage. The state of charge indicator still further f'~ includes storage system for storing each result at -~ corresponding time intervals and producing an accumulated status and output system coupled to the storage syste~ ~or ~,J-~i 25 producing the indication in response to the accumulated status exceeding an accu~ulated ~tatus threshold.
In accordanc2 with the present invention, the input system of the state o~ charge indicator may further produce a recharge tap voltage. The state o~ charge indicator o~
the present invention may further comprise recharge monitor system for forcing the output system to continue providing `i~ the indication when the accumulated status no longer :.' exceeds the accumulated status thre~hold and when th~
. recharge tap voltage remains below a recharge threshold.
The present invention fur~her provides a state of charge indicator for providing an indication when the state of charge of a battery falls below a predetermined threshold levPl. The state o~ charge indicator includes ..~.
,' ' 1..1.&~10 i :
: - 5 -input system for sensing a volta~ produced by the battery ;:~ and producing a plurality of tap voltages and a plurality of monitor stages coupled to the input system and havin~ a common output. Each monito:r stage includes sensinq system ~: 5 for sensing one tap voltage oP the plurality o~ tap i;~ voltages and producing a result when the one tap voltage ~; falls below a predetermined threshold. Each monitor stage further includes storage system coupled to the sensing ~,~ system for storing each result at correspondiny time ~ 10 intervals, the storage system having an output coupled to ,,~ the common output for supplying an accumulated status. The state of charge indicator further includes comparator system coupled to th~ common output ~or prodllcing a signal when the accumulated statu3 exceeds a predetermined accumulated status threshold and output system coupled to ~ the comparatQr system for providing the indication in '~; response to the signal.
~ Th~ present invention still further provides a method !~''' of monitoring a voltage produced by a depleta~le energy source and producing an indication when the state of charge of th2 depletable energy sourc~ ~alls below a predetermined threshold. The method includes the steps of sensiny the voltage and producing a plurality of tap voltages, comparing each tap voltage to a corresponding threshold voltage and producing a result ~or each tap voltage falling below i~ corri3ponding threshold volt~ga, producing an accumulated statUs of the result5, and providing the indication when the accumulated status exceeds an ~` accumulated status threshold.
BRIE~ DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are set forth with particularity in . the appended claims. The invention, together with ~urther ob j ects and advantages thereof, may best be understood by making reference to the following des::ription takerl in conjunction with the accompanying drawing, in the sole - ~igure oi which identical re~erence characters indicate . ~: is1entical elem~nts, and wheri~in the ssle ~igure is a ~ ,:
~ 3 ~
,;
,. - 6 -: schematic diagram illustrating the manner in which the present invention may be implemented ln hardware form in accordance with the preferred embodiment of the present . invention.
..
~ 5 DE~ IPTION OF THE_PREFERRED EMBODI~ENT
;~ Re~erring now to the sole figure, it illustrates a state of charge indicator 10 embodying the present ~i invention. The state of charge indicator 10 is oE the type ~` which monitors a voltage produced by a depletable energy ~:: 10 source such as a battery 11 and provides an indication when the state o~ charge of the depletable ener~y source ~alls below a predetermined threshold.
The stat~ o~ charge indicator 10 generally includes input system 13, a threshold generating syste~ 46, monitor sy tem 65, comparator system 134 and output system 152.
The monitor system 65 may include one or more monitor stages such as first monitor stage ~6, second monitor stage 68 and third monitor stag~ 70. The state of charge indicator 10 also includes recharge monitor system 168 and clock system 178.
The input system 13 o~ the state of r:harge indica~or 10 includes a positive input 12, a negative input 14, and resistors 1 , 24, 30, 36, and 42. The positive input 12 and the negative input 14 are preferably coupled to the terminals of the depletable energy source 11. The negative input 14 preferably ~orms or provides system ground. The positive input 12 is coupled to the first end 16 of re~istor 13. The second end 20 of the resistor 18 is coupled to the first end 22 of resistor 24. The second end 26 of the resistor 24 i~ coupled to the first end 28 o~
resistor 30. The second end 32 of the resistor 30 is coupled to the first end 34 of resistor 3~. The second end 3~ of the resi~tor 36 is coupled to the ~irst end 40 o~
resistor 42. The second end 44 of resistor 42 is coupled to the negative i~put 14. Resistor 18, resistor 24, resistor 30, resistor 36, and re8istor 42 form input system i~ 13 Por sensi~g the voltag~ between the positiv~ input 12 ,~, !
~`',~'' ~;
and the negative input 14 and producing a plurality of tap voltages.
Also coupled to the positive input 12 i5 the threshold generating system 46. The threshold generating system 46 includes a diode 48, a resistor 52, zener diodes 50, 60 and 62, and capacitor 58. The anode of the diode 48 i5 coupled ~ to the positive input 12. The cathode of the diode 48 is 5~;~ coupled to the cathode o~ the zener diode 50 ~nd a first end 53 o~ the resistor 52. ~he anode of the zener diode 50 ~`~ 10 i~ coupled to the negative input 14. The second end 56 of ~-~ the rasistor 52 is coupled to a vcr node 54. The VCC node .~ 54 is preferably provided with a voltage of +5 volts and ~; provides positive supply voltage to other components of the state of charge indicator lo. The capacitor 58 is ~oupled between the second end 56 o~ the resistor 52 and the negative input 14. The cathode of the zener diode 60 is coupled to the ~econd end 56 o~ the resistor 52. The anode ~; o~ the zener diods 60 is coupled to a re~rence node 64.
The cathod~ of the zener diode 62 i~ coupled to the ~s 20 reerence node 64. The anode of the z~ner diode 62 i5 coupled to the negative input 14.
In the operation of the threshold generating syst8m 46, a reference voltage is provid~d at the re~erence node 64. This reference voltage iB preferably temperature and current compensated as is well-kno~n in the art. This . reference voltage is used ~or producing threshold voltages corresponding to each tap voltage produced by th~ input system 130 The ref rence node 64 is coupled to monitor system ~5.
The monitor syste~ 65 includes first, second and third monitor stages 66~ 68 and 70.
The ~irst monitor qtage 66 includes monitor syste~ 74 ~` and storag~ syste~ 75. The storage system 75 includes shift register 82 and resistor~ 88a, 88b, 88c, 88d, 88e, ~: 35 88f, 88g, and 88h. In the first ~onitor ~age 66, ~
~; re~istor 72 is coupled betwPen the re~erence node 64 and the monitor system 74. The monitor system 74 includes an operational ampli~ier 76 and a ~eedback resistor 78. The "~
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,. i . ..
211~910 ~;~
output of th~ monitor system 74 is coupled to an input 80 of shift register 82. The shift register 82 also has a ~-: clock i~put 84. The shift register 82 furth~r has outputs 86a, 86b, 86c, 86d, 86e, 86f, 86g, and 86h coupled to resistors 88a, 88b, 88c, 88d, 88e, 88f, 88g, and 88h, rsspectively, which have a common connection to form an output 90 of the first monitor stage 66.
The second monitor stage 68 include~ monitor system 94 and storage system 95. The storage sy~tem 95 include~
shift register 102 and resi~tor~ 108a, 108b, 108c, 108d, 108e, 108f, 108g, and 108~l. In the second monitor stage 68, a resistor g2 i~ coupled between the reference node 64 and the monitor system 94. The monitor syst~m 94 include~
an operational amplifier 96 and a ~eedback resistor 98.
The output of the monitor system 94 is coupled to an input 100 of the shift register 102. The shift register 102 also has a clock input 104. The shi~t register 102 has outputs 06a, 106b, 106c, 106d, 106e, 106f, 106g, and 106h coupled to resistors 108a, 108b, 108c, 108d, 108e, 108~, 108g, and lOSh, respectively, which have a co~mon connection to form ~' an output 110 of the second monitor stage ~8.
The third monitor stage 70 includes monitor ~ystem 11 and storage system 115. The storage system 115 include~
shift register 122 and resistors 128a, 128b, 128c, 128d, . ~ 25 128e, 128f, 128g, and 128h. In the third monitor stage 70, . ~ a resistor 112 is coupled between th~ reference node 64 and the monitor sy~tem 114. The monitor system 114 includes an operational amplifier 116 and a fe~dback resistor 118. The output of the monitor system 114 is coupled to an input 120 . 30 of a shift register 122. The shift regi~ter 122 al~o h~s ;~ a clock input 124. The shift register 12~ has outputs . 126a, 126b, 126c, 126d, 126e, 126f, ~26gt and 126h coupled to resistors 128a, 128b, 128c, 128d, 128e, 128f, 128g, and 128h, respectively, which have a common connection to form an output 130 of the third monitor stag2 70.
.
~ The output 90 of the first mon1tor stage 6S, th~
" c~utput 110 of the ~cond monitor ~tage 68 and the output 130 of t:he third monitor stage 70 ar~ coupled together to ~, , ~' 21 1 ~91~
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form a common output 132. The common output 132 is coupled to the comparator system 134. The comparator system 134 includes a resistor 136, an operational amplifier 138, a feedback resistor 140 and 2 resistor 144. The inverting input of the operational amplifier 138 is coupled to the reference node 64. The operational ampli~ier 138 has an output 142 coupled to a fir~:t end 146 of the r2sistor 144.
The second end 148 of the resistor 144 is coupled to node 150.
Node 150 is also coupled to the output system 152.
The output system 152 include~ a latch system 154 and an output device 162. The latch system 154 includes an operational amplifier 156 and a feedback r2sistor 158. The output of the latch system 154 i5 coupled to a resistor 160. The resistor 160 is further coupled to the output device 162 whi~h may be a switchi~g device such as a field effec~ transistor. In the embodiment sho~n in the figure, th~ output device 162 is coupled to a light emitting diode 164. The anode o~ the light emitting diode 164 is coupled to a current limiting resistor 166. The re~istor 166 i~
Goupled to the positive input 12. ~hus, when the output system 152 provides an indication of low state of charge, light emitting diode 164 is illuminated. The low state of charge indication may be any visual, electrical, audible, or other signal capable of indicating the low state of charge condition to the user.
The state of charge indicator 10 also includes recharge monitor system 168. The first end 40 of resistor 42 o~ the input ~yste~ 13 is al50 c3upled to the recharge monitor system 168. The recharge monitor ~ystem 168 includes a resistor 170, an operational amplifier 172, a ~eedbac~ resistor 174 and a resistor 176. The inverting input of the operational amplifier 172 is coupled to the ,..
r~fsrence node 64. The reoharge monitor system 168 has an output 173 coupled to a ~irst end 175 of the resi~tor 176.
The second end 177 of the re~istor 176 is coupled to node ` 150.
.' .~
Lastly, the state of charge indicator 10 includes a clock system 178 for providi~g a plurality of clock ~: signals. Clock system 178 includes a resistor 180, a capacitor 182 and a clock generator lQ4. The clock generator 184 provides clock signals on outputs 186, 188, and 190. Output 186 is coupled to the clock input 84 of the shi~t register 82. Out:put 188 i~ coupled to the clock input 104 of the shift register 102. Output 190 is coupled to the clock input 124 of the shift register 122. The clock generator 184 generates alock signals at a rate determined by the values of resistor 180 and capacitor 182.
''. Preferably, the frequencies o~ clock signals provided on outputs 186, 188 and 190 are diffexent. Preferably the frequency of the clock siqnal provided on output 190 i8 lower than the frequency of the clock signal provided on output 188. Also, preferably the fre~uency of the clock slgnal provided on output 188 is lower than the frequency ~; of the clock signal provided on output 186.
a For monitoring a voltage produced by a depletable energy source and providing an indication when the state o~
ch~rge of the depletabl~ energy source falls below a predetermined threshold, positive input 12 ~nd negatiYe ~r~ input 14 are coupled to the output ter~inals of the depletable ener~y sour e. The resistors 18, 24, 30, 3~, . 25 and 42 form a voltage divider. The voltage divider produces tap voltages proportional to the voltage batween j positive input 12 and negative input 14. A first tap voltage is producediat the second end 20 o~ the resistor 18 ~i~ and supplied to the inverting input of the operational ` 30 amplifier 76 of the monitor system 74 of th first moni or stage 66~ The monitor syste~ 74 form~ a comparator with . hysteresis, well-known in the art~ The magnitude of the tap voltage supplied to the inverting input of the operational amplifier 76 is compared with a threshold voltage at the noninverting input of operational amplifier 76. When the tap voltage supplied to ~onitor system 74 is ~: greater than the threshold voltag~ supplied to the monitor ~. system 74, the output o~ the monitor system 74 will be a ;i,`~:
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.~` , '~. voltage corresponding to a logical 0 value. Wh~n the tap voltage supplied to khe monitor system 74 is l~ss than the threshold voltage supplied to the monitor ~ystem 74, as when the state oE charge of the depletable energy source coupled to positive input 12 and negative input 14 is *~ diminished in value, the output of the monitor ~ystem 74 ~: will be a voltage corresponding to a logical 1 value.
,.i~ The output produced by the monitor system 74 is supplied to the inpu~ 80 of the shift register 82. The shift register 82 prefPrably includes a plurality of storage locations, each storage location having an associated order, the order being from highest to lowest.
In response to a clock signal received at clock input 84, the shi~t register 82 discards th~ contents of the highest-ordered storaye location, sequentially moves the contents of each storage location to the next highest-ordered `~ ~tor~ge location, and stores the logical value supplied at : input 80 in the lowest ordered storage location.
-~ Preferably, shift register 82 inoludes eight such storage locations. The contents of each such storage location is ~;~ supplied to outputs 86a, 86b, 86c, 86d, 86e, 86f, 86g, and -`~` 86h, respectively. A voltage corresponding to the sum o~
the contents o~ the eight storage locations of the shit register 82 i~ ~up~lied to output 90 of first monitor stage ~, 25 66.
Thus, the first monitor stage 66 compares the tap ~:~ voltage at the second end 20 o~ the resistor 18 with a corre~ponding threshold voltage and produces a result.
Responsive to clock signals from the clock system 178, the ~: 30 ~irst monitor stage 66 stores the results o~ the eight preceding comparisons. The results of these comparisons are summed and a voltage corresponding to the sum is provided at th~ output 9 0 .
In a similar manner, thr second monitor stage 68 compares the tap voltaye at the second end 26 of the r~sistor 24 with a corresponding threshold voltage and produces a result. Responsive to clock signals from the ~3i!,; clock system 178, thP second monitor stage 68 stores the ..
j~
results of the eight preceding comparisons. The results of these comparisons are summed and a voltage corresponding to the sum is provided to the output llo.
In like manner, the third monitor stage 70 compares thP tap voltage at the second end 32 of the resistor 30 ~: with a corresponding threshold voltage and produce~ a resultO ResponsiYe to clock signals ~rom the clock system 178, the third monitor stage 70 ~tor~$ the re~ult~ o~ the eight preceding comparison~. The results o~ these comparisons are summed and ia voltage correspanding to the sum is provided to the output l.30.
As noted above, the clock signals provided at the outputs 186f 188 and l9o o:E the clock system 178 to the . first monitor stage 66, the second monitox stage 68, and the third monitor stage 70, respectlvely, preferably have dif~ering frequencies. Preferably, ~he clock signal provided to the first monitor stage 66 has a greater frequency than the clock signal provided to the ~econd ~; mo~itor stage ~8 and the clock signal provided to the second monitor stage 68 has a gr~ater ~requency than ~he cloc~ signal provided to the third monitor stage 70. Thus, ~'~ the first monitor stage 66, which co~pares the tap voltage . having the highest voltage magnitude which correspond~ to the threshold voltage having the lowest voltage magnitude, ~` 25 stores the results of the comparisons most frequently.
Si~ilarly, the third monitor stage 70, which compares the tap voltage having the lowest voltage magnitude which ~-` corresponds to the threshold voltags having the highest '~! YOltage magnitude, stores the results of the comparison '~ 30 least frequently.
~ During the discharge cy~le oP a battery, the battery ;~. voltage decreases as the battery state o~ charge decr~ases for a given discharge rate. Similarly, the voltage decreases as the rate of disGharge increases for a given ~tate of charge condition. Each stage compares the battery voltage to different threshold voltages at di~erent rates.
,~ A relatively low battery voltage can be attributed t~ two . conditions: the rate of dis~harge i5 high or the battery 9 1 ~
state of charge is low. Both of these condition6 necessitate that the sampling rate for the st~ge with the `~ lower threshold voltage be r~latively fast in order that ~ the battery monitor indicates bePore the battery state of ,~: 5 charge fall~ well below the predetermined state o~ charge ~;~ threshold. Conversely, a relatively high battery voltage indicates that the battery c;tate of charge is high or that j~. the discharge rate is low. These two conditionsnecessitate that the sample rate for the stage with the higher threshold voltage be relatively slow. In this ~` second scenario, there is plenty of timc to identi~y the low state of charge conditi~n before the battery state oP
~.~ charge falls below the predetermined state o~ charge j threshold. Through proper sel~ction of thre~hold voltage~
and storage rates, a given state of charye can be correctly identified ~or varying discharge conditions t~ a high level ~: of precision.
~; The embodiment of the present invention shown in the ~: drawing includes three monitor stayes, the first monitor stage 66, the second monitor stage 68, and the third ~:~ monitor stage 70. As will be appreciated by those skilled in the art, a dif~erent number of ~onitor stages may be utilized without departing from the present invention. The number of ta~es required is dependent upon the application for which the baktery coupled to the state of charge indicator ~0 is used. More monitor stages will be rPquired in application~ which have a broad current range, i.e., 3 current range from 0 to 150 amperes during use or in .
applications in which the current supplied by the battery 3G varies greatly, i.e., the current fluctuat~s during use ~rom 0 to 75 to 25 to 100 amperes. Also, the state of ; charge indicator will require more ~tages for applications : in which it is desirable to increase the accuracy of the .: state of charge indicator.
The clock ~requencie~ supplied by the clock system 178 -~ and the predetermined threshold voltages corresponding to each tap voltage are chosen based on known characteristic~
of the battery to which th~ ~tate of charge indicator 10 i8 7 1 1 ~ 9 10 ~ coupled. The frequencies and threshold voltages are also I ~ pre~erably cho5en so that state o~ charge indicator 10 will provide the state of charge indication at any predetermined level from 0% to 100% state o~ charge and to some level o~
precision, such as a 5% band about the predet~rmin2d state of charge level.
The comparator system 134 monitors the accumulated status produced at the common output 132 o~ the first r~ monitor stage 66, the secsnclmonitor ~tage 68 and the third monitor stage 70. The accumulated status i8 supplied ts ,.
.~ the noninverting input of the operational amplifier 138.
The re~erence voltage on the re~erence node 64 is supplied to the inverting input of the operational a~pli~ier 138.
When the voltage magnitude of the accumulated status is . 15 less than the voltage magnitude of the reference voltage at node ~4, the output of the operational amplifier 138 corresponds to a logical 0 value. This logical 0 value indicates that he state of charge indicator has not detected a low state o~ charge conditi~n. When the voltage magnitude of the accumulated status is greater than the re~erence voltage, the outpu~ of the operational amplifiex ~,. 13B will have a value corresponding to a logical 1 value.
This logical 1 value indicates that the state of charge `: indicator 10 has detected a low state of charge indication.
., The recharge monitor system 16~ monitors a recharge tap voltage produced at the second end 38 of the resistor :~ 36. The recharge tap voltage is supplied to the ~ noninverting input of the operational amplifier 172. The ,-~ reference voltage is supplied on the reference node 64 to ~: 30 the inverting input of operational amplifier 172. When the recharge tap voltage has a voltage magnitude greater than ~ the reference voltage supplied on the reference nod~ 64 the ;~ output of the operational ampli~i~r ~72 ha~ a logical 1 value. When the recharge tap voltage ha~ a voltage magnitude less than the re~erence voltage, ths output o~
the operational amplifier 172 has a logical 0 value. The logical 1 value at the output of the operational amplifier 172 indicates that the depletabl~ energy source coupled across the positive input l2 and the negative input 14 is charging or is ~ully charged. The logical 0 value at the output o~ the operational ampliPier 172 indicates that the ,~` depletable energy source i6 not charging or is not fully charged. The recharge monitor system 168 is used for forcing the output device 162 to continue providiny a low state o~ charge indication when the accumulated status no ~: longer exceeds the accumulated status threshold and when ~ the recharge tap voltage falls below the recharg '}`~ 10 threshold. Thus, the output of the operational amplifier ~- 172 provides a recharge signal.
An important aspect o~ thQ present invention i~
provided by the latch system l54. The latch system 154 ~orms an output control system for controlling the output device 162 in response to the comparator system 134 and the recharge monitor system 168. The operation of the latch ~: ~ystem 154 is shown in the truth table, Table I.
~; Previous Charging Accu~ulated ' Next Output ,~ Output 1156i 1172~ Statu~ (l38L I (l56L
.. 20 o o o I o .~' O 0 1 1 1 ,,"~ 1 0 0 }
~ 25 1 0 l j 1 i'.' 1 1 0 ' O
, ~ 1 1 1 ' 1 TABLE I
As will be noted ~rom Table I, the next output, the ~ 30 output of th~ operational amplifier 156, is a function of r, ~he previous output, which is the output of the operational amplifier 156, the recharge 6ignal, which i8 th~i output o~
the oparational ampli~'ier 172, and the accumulated status . which is the output of the operational amplifier 138~ When th~ next output has a logical 0 value, the output device ir~ 162 will not provide a low state of charge indication.
,',f~ Similarly, when the next output has a logical value 1, the ~ 21 1~10 ; 16 -,, output device 162 will provide 21 low state of charge indication.
~!~ As can thus be seen in Table I, the ~tate of the next . output generally tracks the state of the accumulated . 5 status. However, where the accumulated status is a O,indicating the battery does not presently have a low state o~ charge, and the charging output i5 a 0, indicating the , battery i8 not recharging or fully charged, and the previous output was a 1, indicatiny a low state o~ charge, the next output remains a :Logical l~ indicating low state ~v o~ charge. Thu~, the state o~ charge indicator 10 is .- rendered insensitive to short~term ~luctuations o2 the output voltage of the depletable energy source. Once the ~; state of charge indicator 10 ha~ detected a low state o~
;-~ 15 charge and provided an indication through the oukput device , 162, the low state of ¢harge state is latched by the latch system 154. The latch ~ystem 154 is only reset by a logical 1 on the charging output, the output o~ the operational amplifier 172 9 a,~ 20 From the ~oregoing, it can be seen that the present invention provides a new and improYed state of charge indicator for monitoring a voltage produced by a d2pletabl2 ~: energy scurce and providing an indication when the state of charge o~ the depletable energy sourc~ ~alls below a pr~determined threshold. In addition, ~he state of charge ~- indicator of th2 present invention assures that th~ low state of charge indication will continue to be provided until the depletable energy source has been recharged to well above the predetermined setpoint level.
.; 30 ~hile a particular embodiment of the present invention has been shown and described, modifications may be mad~, and it is therefore intended in th~ appended claim~ to cover all such changes and modificatlons which ~all within the true spirit and scope o~ th~ inYention.
~'' ~.
~ ,- ~ ~
:
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A state of charge indicator (10) for providing an indication when the state of charge of a battery (11) falls below a predetermined threshold level, characterized by:
an input system (13) for sensing a voltage produced by the battery (11) and producing a plurality of tap voltages;
a plurality of monitor stages (66, 68, 70) coupled to the input system and having a common output (132), each monitor stage of the plurality of monitor stages (66, 68, 70) including a monitor system for sensing one tap voltage of the plurality of tap voltages and producing a result when the one tap voltage falls below a predetermined threshold and a storage system (75, 95, 115) coupled to the monitor system for storing each result, the storage system (75, 95, 115) having an output (90, 110, 130) coupled to the common output (1323 for supplying an accumulated status;
a comparator system (134) coupled to the common output (132) for producing a signal when the accumulated status exceeds a predetermined accumulated status threshold; and an output system (152) coupled to the comparator system (134) for providing the indication in response to the signal.
an input system (13) for sensing a voltage produced by the battery (11) and producing a plurality of tap voltages;
a plurality of monitor stages (66, 68, 70) coupled to the input system and having a common output (132), each monitor stage of the plurality of monitor stages (66, 68, 70) including a monitor system for sensing one tap voltage of the plurality of tap voltages and producing a result when the one tap voltage falls below a predetermined threshold and a storage system (75, 95, 115) coupled to the monitor system for storing each result, the storage system (75, 95, 115) having an output (90, 110, 130) coupled to the common output (1323 for supplying an accumulated status;
a comparator system (134) coupled to the common output (132) for producing a signal when the accumulated status exceeds a predetermined accumulated status threshold; and an output system (152) coupled to the comparator system (134) for providing the indication in response to the signal.
2. A state of charge indicator (10) of claim 1, further characterized in that a recharge monitor system (168) is coupled to the input system (13) for monitoring one tap voltage of the plurality of tap voltages and generates a recharge signal when the one tap voltage of the plurality of tap voltages exceeds a recharge threshold.
3. A state of charge indicator (10) of claim 2, further characterized in that an output control system (152) is coupled to the comparator system (134), the output device (162) and the recharge monitor system (168) responding to the comparator system (134) and the recharge monitor system (168) and controlling the output device (162) by forcing the output device (162) to continue providing the indication when the comparator system (134) no longer produces the signal.
4. A state of charge indicator (10) of claim 1, further characterized in that the storage system includes a plurality of storage locations (75, 95, 115) for storing a like plurality of the results, each storage location of the plurality of storage locations (75, 95, 115) having an associated order, the order being from highest to lowest, and wherein the storage system is responsive to a clock signal (84, 104, 124) for discarding the contents of the highest ordered of the storage locations, sequentially moving the contents of each storage location of the plurality of storage locations (75, 95, 115) to the next highest ordered storage location and storing the result in the lowest ordered of the storage locations, each storage location of the plurality of storage locations (75, 95, 115) being coupled to the common output (132).
5. A state of charge indicator (10) of claim 4, further characterized in that the storage system (75, 95, 115) includes a shift register (82, 102, 1223 and each storage system of the plurality of monitor stages (66, 68, 70) is coupled to a different clock signal of a plurality of clock signals (84, 104, 124) generated by the clock system (178).
6. A state of charge indicator (10) of claim 1, further characterized in that each monitor system of the plurality of monitor stages (66, 68, 70) is coupled to a different predetermined threshold of a plurality of predetermined thresholds generated by threshold generating system (46).
7. A method of monitoring a voltage produced by a depletable energy source (11) and producing an indication when the state of charge of the depletable energy source (11) falls below a predetermined threshold, characterized by:
sensing the voltage and producing a plurality of tap voltages;
comparing each tap voltage of the plurality of tap voltages to a corresponding threshold voltage and producing a result for each the tap voltage falling below its corresponding threshold voltage;
producing an accumulated status from the results;
and providing the indication when the accumulated status exceeds an accumulated status threshold.
sensing the voltage and producing a plurality of tap voltages;
comparing each tap voltage of the plurality of tap voltages to a corresponding threshold voltage and producing a result for each the tap voltage falling below its corresponding threshold voltage;
producing an accumulated status from the results;
and providing the indication when the accumulated status exceeds an accumulated status threshold.
8. A method as defined in claim 7, further characterized by the step of periodically storing the results and combining the results to produce the accumulated status.
9. A method as defined in claim 8, further characterized by the step of providing a clock (178) for clocking the periodic storing of the results.
10. A method as defined in claim 7, further characterized by the step of monitoring one tap voltage of the plurality of tap voltages and generating a recharge signal when the one tap voltage of the plurality of tap voltages exceeds a recharge threshold.
11. A method as defined in claim 10, further characterized by the step of forcing the output system (152) to continue providing the indication when the accumulated status no longer exceeds the accumulated status threshold and when the one tap voltage does not exceed the recharge threshold.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/030,648 | 1993-03-12 | ||
| US08/030,648 US5416402A (en) | 1993-03-12 | 1993-03-12 | State of charge indicator for deep-cycle application |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2116910A1 true CA2116910A1 (en) | 1994-09-13 |
Family
ID=21855243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002116910A Abandoned CA2116910A1 (en) | 1993-03-12 | 1994-03-03 | State of charge indicator for deep-cycle applications |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5416402A (en) |
| EP (1) | EP0615133A1 (en) |
| JP (1) | JP3545449B2 (en) |
| KR (1) | KR940022977A (en) |
| AU (1) | AU664513B2 (en) |
| BR (1) | BR9401132A (en) |
| CA (1) | CA2116910A1 (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5870025A (en) * | 1994-04-26 | 1999-02-09 | Canon Kabushiki Kaisha | Power-supply apparatus and its mounting-completion indication method |
| FR2721715B1 (en) * | 1994-06-24 | 1996-08-23 | Alsthom Cge Alcatel | Device for measuring the state of charge of an electrochemical generator. |
| US5640150A (en) * | 1995-08-17 | 1997-06-17 | The United States Of America As Represented By The Secretary Of The Army | Resettable state-of-charge indicator for rechargeable batteries |
| US6624618B2 (en) | 2001-01-25 | 2003-09-23 | Ford Global Technologies, Llc | System and method for vehicle voltage regulation |
| DE10121962A1 (en) | 2001-05-05 | 2002-11-07 | Vb Autobatterie Gmbh | Energy management system for motor vehicle on-board electrical system controls energy distribution taking into account current generation, storage, consumption component efficiencies |
| DE10126891A1 (en) * | 2001-06-01 | 2002-12-05 | Vb Autobatterie Gmbh | Predicting electrochemical element load capacity involves correcting equivalent circuit input voltage w.r.t measured voltage using function with logarithmic current dependency as nonlinear term |
| US6727708B1 (en) | 2001-12-06 | 2004-04-27 | Johnson Controls Technology Company | Battery monitoring system |
| DE10210516B4 (en) | 2002-03-09 | 2004-02-26 | Vb Autobatterie Gmbh | Method and device for determining the functionality of a storage battery |
| DE10215071A1 (en) * | 2002-04-05 | 2003-10-30 | Vb Autobatterie Gmbh | Method for determining the wear of an electrochemical energy store and energy store |
| DE10224662C1 (en) * | 2002-06-03 | 2003-06-18 | Vb Autobatterie Gmbh | Battery charge state indicator has ball channel with upper bounding wall with opening for viewing rod tip aligned with reflective surface at transition to cylindrical surface of viewing rod |
| US20030236656A1 (en) * | 2002-06-21 | 2003-12-25 | Johnson Controls Technology Company | Battery characterization system |
| DE10231700B4 (en) * | 2002-07-13 | 2006-06-14 | Vb Autobatterie Gmbh & Co. Kgaa | Method for determining the aging state of a storage battery with regard to the removable amount of charge and monitoring device |
| DE10236958B4 (en) * | 2002-08-13 | 2006-12-07 | Vb Autobatterie Gmbh & Co. Kgaa | Method for determining the removable amount of charge of a storage battery and monitoring device for a storage battery |
| DE10240329B4 (en) * | 2002-08-31 | 2009-09-24 | Vb Autobatterie Gmbh & Co. Kgaa | Method for determining the charge quantity of a storage battery and monitoring device for a storage battery that can be taken from a fully charged storage battery |
| DE10252760B4 (en) * | 2002-11-13 | 2009-07-02 | Vb Autobatterie Gmbh & Co. Kgaa | Method for predicting the internal resistance of a storage battery and monitoring device for storage batteries |
| DE10253051B4 (en) | 2002-11-14 | 2005-12-22 | Vb Autobatterie Gmbh | Method for determining the charge acceptance of a storage battery |
| US7282891B2 (en) * | 2002-12-30 | 2007-10-16 | Motorola, Inc. | Method for charging a battery |
| US6888468B2 (en) * | 2003-01-22 | 2005-05-03 | Midtronics, Inc. | Apparatus and method for protecting a battery from overdischarge |
| DE10335930B4 (en) | 2003-08-06 | 2007-08-16 | Vb Autobatterie Gmbh & Co. Kgaa | Method for determining the state of an electrochemical storage battery |
| DE102004005478B4 (en) * | 2004-02-04 | 2010-01-21 | Vb Autobatterie Gmbh | Method for determining parameters for electrical states of a storage battery and monitoring device for this purpose |
| DE102004007904B4 (en) * | 2004-02-18 | 2008-07-03 | Vb Autobatterie Gmbh & Co. Kgaa | Method for determining at least one parameter for the state of an electrochemical storage battery and monitoring device |
| FR2870661A1 (en) * | 2004-05-19 | 2005-11-25 | France Telecom | METHOD FOR OPTIMALLY MANAGING THE CHARGE OF A BATTERY OF A MOBILE TELECOMMUNICATION TERMINAL |
| DE102006024798B3 (en) * | 2006-05-27 | 2007-03-22 | Vb Autobatterie Gmbh & Co. Kgaa | Automotive lead-acid battery has electrolyte float gauge depth detector with ball cage |
| US7475319B2 (en) | 2006-08-24 | 2009-01-06 | Advantest Corporation | Threshold voltage control apparatus, test apparatus, and circuit device |
| US8188876B1 (en) | 2009-05-29 | 2012-05-29 | Brunswick Corporation | Integrated battery level indicator, method and circuit for a trolling motor controller |
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| US4052717A (en) * | 1975-10-14 | 1977-10-04 | Goodyear Aerospace Corporation | Battery condition monitoring method and apparatus |
| US4193026A (en) * | 1976-04-18 | 1980-03-11 | Curtis Instruments, Inc. | Method and apparatus for measuring the state of charge of a battery by monitoring reductions in voltage |
| US4560937A (en) * | 1981-11-16 | 1985-12-24 | Curtis Instruments, Inc. | Battery state of charge metering method and apparatus |
| US4740754A (en) * | 1986-01-13 | 1988-04-26 | Curtis Instruments, Inc. | Bidirectional battery state-of-charge monitor |
| US4835453A (en) * | 1987-07-07 | 1989-05-30 | U.S. Philips Corp. | Battery-powered device |
| GB8821167D0 (en) * | 1988-09-09 | 1988-10-12 | Jaguar Cars | Electrical supply control system for motor vehicle |
| JPH04110785A (en) * | 1990-08-31 | 1992-04-13 | Fujitsu Ltd | Battery alarm device |
| JP2650505B2 (en) * | 1991-03-29 | 1997-09-03 | 株式会社ユアサコーポレーション | Battery remaining capacity meter |
| US5130699A (en) * | 1991-04-18 | 1992-07-14 | Globe-Union, Inc. | Digital battery capacity warning device |
| DE4132229C2 (en) * | 1991-09-27 | 1994-02-24 | Mentzer Electronic Gmbh | Microcontroller-controlled device for analyzing the state of charge of a multi-line battery |
-
1993
- 1993-03-12 US US08/030,648 patent/US5416402A/en not_active Expired - Fee Related
-
1994
- 1994-03-03 CA CA002116910A patent/CA2116910A1/en not_active Abandoned
- 1994-03-03 EP EP94250055A patent/EP0615133A1/en not_active Withdrawn
- 1994-03-09 AU AU57703/94A patent/AU664513B2/en not_active Ceased
- 1994-03-11 BR BR9401132A patent/BR9401132A/en not_active Application Discontinuation
- 1994-03-11 KR KR1019940004841A patent/KR940022977A/en active IP Right Grant
- 1994-03-11 JP JP06798994A patent/JP3545449B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0615133A1 (en) | 1994-09-14 |
| AU664513B2 (en) | 1995-11-16 |
| KR940022977A (en) | 1994-10-22 |
| US5416402A (en) | 1995-05-16 |
| BR9401132A (en) | 1994-11-15 |
| JP3545449B2 (en) | 2004-07-21 |
| JPH075210A (en) | 1995-01-10 |
| AU5770394A (en) | 1995-06-08 |
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