CA2101077C - Battery with strength indicator - Google Patents

Abstract

A battery strength indicating and switch means (12) on a battery (18) which is coupled across the terminals (20) of the battery and which is provided with an indicating means to indicate the strength of the battery. Additionally, the battery strength indicating means is also provided with an in-line switch which can easily be depressed to complete the circuit so as to place the indicator means across the terminals of the cell and display the charge of the battery.

Description

'O 92/13368 PCT/US91/00602 DT;SCRIPTION
IjATTI:RY WIT11 S'l.'R13NGTil INDICATOR
'I'eclmi.ca7. 1~ Iel.d '1'lve present invention relates to an improved vattery having; a o; built-in strengttr indicator device for determining the stren6th, voltage, or capacity of the battery. More particularly, the present invention relates to a batter, having an indicator cell which visually indicates when the battery is above or below a predeterTnined voltage value, an Lt;D array which indicates when the battery is above or below IU a predetermined voltage vaguer, or a redox cell which indicates when the volta6e output is above or below a predetern~ined voltage by a color change.
Background Art flatteries are employed extensively in this country and abroad for l~; automobiles, hcxne uses, industrial uses, recreational uses, and military uses. A battery is normally tested by rneasuring its voltage output without a load. If ithe voltage is below a predetermined value, and the voltage characteristics of the battery with respect t.o the . ~ CA 02101077 1999-10-27 battery' s capacity are known, one can determine whether the battery has sufficient capacity to perform a desired function: A more accurate indication of the battery's condition can bE: determined by noting the voltage drop of the battery under a load. A well-charged battery will experience only a slight voltage drop under a load, whereas a depleted battery will undergo a significant voltage drop under a load. For a wet-cell battery, the work capacity of the battery can frequently be determined by measuring the specific density of the electrolyte.
A dry-cell battery does not have a reservoir liquid electrolyte; thus, its capacity cannot be determined by taking specific: gravity measurements. In addition, voltmeters are expensive, as are devices for measuring the voltage output of a battery, both under a load and under no load. Accordingly, most batteries are purchased or used without the purc:haser/user knowing the true condition of the battery.
Recently, the manufacturer of DURACELL* batteries has been date-marking its packages to indicate by which date the battery should be in use. Although this date-stamping may be of some benefit to purchasers, it does not tell the purchaser the actual condition of the battery. Moreover, date-stamping of the package does not include date-stamping of the battery; i:hus, the purchaser has no idea of the use-date of a particular battery once it has been removed from the package.
U.S. Patent No. 4,962,347 issued on October 9, 1990 discloses a flashlight with a built-in battery tester having a voltmeter, ammeter, or visual-indicating chemical or LED cell to indicate when the battery's voltage output is above or below a predetermined value.
* trade-mark 2101077.
l~lashli~hts, lx~rtable lanterns, portable radios and television, c:amor:«, video recorders, portable dictating machine, and the like are used extensively in this country and abroad. Almost every home and business has at least one flashlight. or portable lantern and a radio.
05 Many home and businesses have numerous devices, such as recorders, portable radios and televisions, video recorders, calculators, cameras, and the like, which utilize batteries for their energy source. Sortie of the devices, suc>'~ as flashlights, are used on an infrequent basis, that is, during a~n emergency situation where there has been a power failure or when it. is not convenient to use a light source powered by conventional household current, such as for outdoor use or use in an unlighted attic or crawl space. Other devices, such as portable radios, are used extensively. The majority of these battery powered devices use dry-cell nonrechargeable batteries.
Nonrechargeable alkaline batteries .old under the trademarks EV~EApy, DUItACELL, RAy-OVAC, and the like, have a number of advantages over rechargeable batteries. On a weight-to-weight and volume-to-volume basis, the alkaline battery can supply three to four times the wattage of a rechargeable battery. In addition, nonrechargeable dry-cell rechargeable batteries put out a higher voltage than dry-cell rechargeable batteries. Many dry-cell rechargeable batteries, even if not in use, have to be periodically charged to keep the batteries from falling below a defined charge level to prevent permanent damage to the batteries. Alkaline batteries, which are used frequently, can have a shelf or storage life of from three to five years. During this period, no maintenance of the battery is required. In contrast, most rechargeable batteries wet-cell and dry-cell will completely discharge WO 92/13368 PCT/US91/0060.' ~1~14 within six months ur less of their ',last recharge.
tdosi. individuals test their bai;,teries by turning on the device in wl~icln tOe ~at.teries are installec9. If the device operates, the individual is normally satisfied that the batteries are operational.
05 Some individuals will test the batteries on a battery tester to determine the condition of the batteries. Some individuals will even test the batteries under both loaded and unloaded conditions to measure the voltage drop. Although it is not complicated to test batteries, it is time consuming to disassemble a device, remove the batteries, test the batteries, and, if they pass the test, reinstall the batteries in the device. It is normally not possible to test new batteries at the time of purchase because of the battery protective packaging.
Accordingly, it is the object of the present invention to provide an improved battery having a built--in battery-strength indicator which permits one to immediately dete:rDnine the battery's strength or condition. Thus, with the improved battery of the present invention, a user can quickly and effortlessly deternrine the strength or condition of a battery. When a battery is easily tested, as the battery of the present invention, the user of the battery is more likely to routinely check the condition of the battery.
Disclosure of the Invention The present invention is directed to an improved battery comprising;
(a) a battery; and (b) a battery-strengtb indicator means to indicate the strength 2101077~
c~i t.l~e t~attery when electrically connected to the battery.
Optic>nally, the battery wilJ1 include a switch means adapted in an "on" position to electrically connect and complete a circuit between the battery and the indicator means.
05 The battery-strength indicator means can comprise:
(a) a nonconductive base l;~yer;
(b) a nonconductive top layer attached to the base layer, a portion of the top layer and base layer forn~ing a chamber therebetween;
(c) first and second conductive means separately and independently positioned between the top layer and the base layer and extending into the chamber, the ends of the conductive means in said sealed chamber fornning electrodies, the other ends of the conductive means adapted to electrically connected to the battery; and (d) indicator means in said sealed chamber adapted to undergo a visible change when the voltage potential across the electrode exceed or crosses a predetermined volt:~ge.
The indicator means can be a liquid-crystal canposition that changes phases when the field b~atween the electrodes or plates exceeds or crosses a predetermined voltage value. lPreferably the chamber is sealed.
In an alternative embodiment of the present invention, the battery strength indicator means comprises:
(a) a first nonconductive layer;
(b) a second nonconductive layer attached to the first layer, a portion of the first and second layers forooing a chamber therebetween, said chamber having first and ~oecond internal opposing walls;

WO 92/13368 PCT/US91/006~
~i~,1 ~ ~ 4 ~ ~
G
(c) a third nonconductivE: layer having a high dielectric con scant attached to the first internal wall of said chamber;
(d) a first conductive plate means sandwiched between the third insulating layer v~d the first :internal wall and isolated from the 05 ctaunver .
(e) a second conductive plate means on the second internal wall;
(f) first and second ~.~.onductive means separately and independently positioned between the first and second nonconductive layer, the ends of the conductive means electrically connected to the first arid second conductive plate means respectively, the other ends of the conductive means adapted to be electrically connected to the battery; and (g) a liquid-crystal composition in said sealed chamber adapted to undergo a visible phase change when the electric field between the first and second plate means exceeds or crosses a predetermined value.
preferably the chamber is sealed.
One embodiment of the switch means of the present invention comprises:
(a) a nonconductive base layer;
(b) a resilient nonconducl;ive top layer attached to the base layer, a portion of the top and base layers forming a chamber having first and second internal spaced apart opposing wells;
(c) a first contact means on the first internal wall of the chamber;
(d) a second contact means on the second internal wall of the chamber;
(e) first and second conductive layers independently and 21010~ys sep.rrutely sandwictred between the top layer and the base layer and c:c~rmoctecl i.o the first and second plate means respectively, the top layer about tire chamber adapted to be pushed toward the base layer so that the Iirst and second contact means come in contact to permit OS current to i'lcrw from the first conductive means to the second conductive means.
In an alternative embodiment of the switch means of the present invention, the switch means comprises:
(a) a nonconductive base layer;
(b) a resilient nonconductive top layer attached to the base layer, a portion of the top and base layers forming a chamber having first and second internal spaced apart opposing walls;.
(c) first and second spaced apart conductive contact means on the first internal wall of the switch chamber;
(d) third conductive contact means on the second internal wall of the chamber; and (e) first and second conductive means independently and separately sandwiched between the top layer and base layer and connected to the first and second conductive contact means respectively, the top layer about the chamber adapted to be pushed toward the base layer so that the third conductive contact means contacts the first and second conductive contact means to complete an electrical connection between the first and second conductive contact means.
In another embodiment of the present invention, the battery-strength indicator means comprises:
(a) a first nonconductive layer;

lt~) a second none~nductive layer attached to the first noncumiuctive layer, a portion of said first and second nonconductive 1 ayens fonninl; a chamber therebetween;
(c) a conductive layer sandwiched between said first and second p5 noncm u.iucaive layers, the conductive layer reduced to a small cross-sectional area in the chamber; and (d) a teat sensitive color-indicating material in said sealed chamber that is adapted to undergo a color change when its temperature exceeds or crosses a predetermined value, said conductive layer in the chamber rising to a predetermined temperature when the voltage of the current flowing therethrough exceeds a predetermined value.
In a further embodiment of the present invention, the battery-strength indicator.meau~s comprises:
(a) a first nonconductiv~a layer;
1; (b) a second nonconductive layer attached to the first nonconductive layer, a portion of said first and second nonconductive layers forming a chamber therebetween;
(c) a conductive layer sandwiched between said first and second nonconductive layers, the conductive layer reduced to a small cross sectional area in the chamber;
(d) a pyrotechnic material contained within said chamber and adapted to decompose when the temperature of the first section of the conductive layer in the chamt~er exceeds a predetermined temperature, the first section of the conductive layer adapted to exceed said predetermined temperature when the voltage of the current through the conductive layer in the chamber exceeds a predetermined value.
In a further embodim~:nt of the present invention, the battery-strength indicator means cou~prises:

(aj a first nonconductive layer;
a sec:und nonconductive layer attached to the first nonconductive layer, a portion of said first and second nonconductive layers forn~ing a chamber therebetween; and 05 (c) a conductive layer sandwiched between said first and second nonconductive layers, the conductive layer reduced to a small cross sectional area in the chamber such that when the voltage of current flow through the conductive layer in the chamber exceeds a predeternrined value, the temperature of the conductive layer in the chamber exceeds the melting i:emperature of the conductive layer causing the conductive layer to melt and foam an open circuit.
The invention also comprises an improved battery package having a battery-strength indicator mean's comprising:
(a) at least one battery;
(b) a battery-strength indicator means comprising:
(i) a battery-strength indicator device for indicating the strength of said battery when electrically connected to said battery;
and (ii) conductive mean; adapted to electrically connect said indicator device to said battery; and (c) packaging means for said battery and battery strength indicator means.
Optionally, the improved batteries can have switch means to electrically connect the battery strength indicator to the battery.
Preferably the chambers of the battery strength indicators are selected chambers.

WO 92/ 13368 PCT/US91 /0060?

_ _ . IU
Description of the Drawing fIG. 1 i:: a Lop view of a battery-stren(;th indic:at.or c)evice of i.iie pr~~:e:nt invention;
t'I(.. 1A is a top view of a battery-strength indicator device of U5 tt» lu-c~sent invention with a switch;
I'IG. 2 is a perspective view of a battery of the present invention having a battery-stren~Tth indicator device;
F1G. 3 is a vertical, sectional view along lines 3-3 of FIG. 1;
F1G. 9 is a top plan view of a battery-strength indicator device lU of the present invention;
FIG. 5 is a vertical, sectional view along line 5-5 of FIG. 4;
F1G. G is a vertical, sectional view of a switch of the present invention with the switch in the off position;
FIG. 7 illustrates is a vertical, sectional view of a switch of 1; tire present invention with the switch in the "on" position;
FIG. 8 is a vertical, sectional view of an alternative switch of the present invention;
FIG. 9 is a vertical, sectional view of an alternative embodiment of the battery-strength indicator device of the present invention;
2U FIG. 10 is a top plan view of another alternative embodiment of the battery-strength indicator device of the present invention;
1'IG. 11 show a top plan view of still a further embodiment of the battery-strength indicator devise of the present invention;
FIG. 12 is a perspective view of the battery packaging of the present invention Craving a battery-strength indicator device;
I'IG. 13 is a schematic diagram of the battery packaging circuitry of the present invention having a battery-strength indicator WO 92/13368 ' PCT/US91/00602 I1 2~ 0~0~~
cic~~.~i cc~ ;
1~'I(;. 1~l is a vertical, :sectional view of an alternative e~ndx~climer~t. of Ltre switch of the present invention;
fIG. 15 is a vertical, sectional view of another embodiment of U5 the l~at.Leiy-stren~t,h indicator device of the present invention; and FIG. 1G is an enlarged, secltional view within encircled line 1G
of 1'1G. 15.
Ptodes ~Cor Carrying; OuC the Invention Deferring to FIG. 1, a battery-strength indicator device 10 of the present invention is illustrated. The indicator device has an indicator chamber, cell or bubble 12 forn~ed in strip 16. Preferably the cells of the present invention are sealed cells. Conductive layers 14 run the length of the strip into the indicator bubble to iorvr spaced apart electrodes. The indicator bubble contains an indicating material 17 which undergoes a visible change when the voltage potential across the indicator cell exceeds a predetermined value. At least one side of the strip 16 is transparent or translucent.
The improved battery 18 of the present invention is illustrated in FIG. 2. The battery has an anode 20 and a cathode at its base (not shown). The indicator device 10 is attached to the side of the battery, with the ends of the device connected to the anode 20 and the cathode. If the device is a constant-drain device, that is, the device is on continuously, the indicator cell undergoes a visible 2S change when the output voltage of the battery drops below a predetermined value. In an alternative embodiment of the invention, ~~p~07~.~

tl~e t,att.ery~ lr~s the indicator device of c 1G. lA, which includes a strip 1G, conductive leads 19, a~a indicator cell 12, and a switch 24.
The sw~itc:h is biased to be in an off position, and, thus, the indicator device is only actuated when the switch is on, thus 05 preventing a constant drain on the battery.
referring to FIG. 3, the indicator device l0A comprised a first layer 30, a second layer 32, and a conductive layer or lead 14 sandwiched between the first and second layers. The end of r the conductive leads extend into thE~ indicator chamber or cell 12, which lU is filled with an indicator matE:rial 33. The ends of the conductive leads form electrodes 36. The :second layer of the device of FIG. 3 is formed with the bulge 37 which :forms one side of the cell. The other side of the cell is formed by t'he first layer. The first layer can be a clear material, a translucent material, or an opaque material. The 15 second layer is preferably a clear or translucent material. The first layer can be an opaque material as long as the bulge area is clear or translucent. Ii the first layer is opaque, the inner side 31 of the first layer can be coated vrith a reflective material such as aluminum or aluminum foil, or a highly reflective white material to enhance 20 visibility of the indicator mai~erial.
The indicator material caua be any material that will undergo a visible change, such as a color change, when the voltage potential across the electrodes exceeds or drops below a predetermined voltage.
For example, the material can be a redox composition, such as the 25 composition in the U.S. Sterling Patent No. 1,497,388, or the compositions disclosed by irl.A. Fales and F. Kenny, INORGANIC
QUANTITATIVE ANALYSIS, 1939, pp. 391-393, or the like. Alternatively, WO 92/13368 . PCT/US91/00602 tire c:oml.~osition can be a liqui~.l-crystal composition, such as one of thc~ cexrrlK»itions disclosed in iKirk-Othmer, I~1CYCL01'EDIA OF CIli:N11CA1, TL;(a INULGG~' , and F.d . , John lh i 1 ey & Sons , Vo 1 . 7 , pp . 724-751 and Vo 1 .
1~, pp. a9S-42?.
OS The voltage color-indicating device of the present invention comprises a sealed cell having at least one transparent or translucent window. The cell is filled with an aqueous or non-aqeous composition, such as an aqueous phenophthalein solution. 'Iwo spaced-apart electrodes of the cell are in contact with the color-indicating solution. When a voltage potential is induced across the electrodes, a redox reaction occurs which can cause a color change iu the color-indicating solution. Each solution has its own unique threshold voltage wherein, the redox reaction will commence. If the voltage of the battery is below that threshold voltage, no redox reaction will occur and there will be no color change.
~1n alternative embodiment of the battery-strength indicator device 1013 of the present invention is illustrated in FIGS. 4 and 5.
The indicator device lOB has a first layer 30, and a second layer 32a, and conductive leads or layers 14 sandwiched therebetween. The second layer 32a has a depression or ~.~.avity 38 which defines one side of the indicator cell 12; the other .side of the cell being defined by the inner surface 31 of the first layer 30. The cavity is illustrated with curved surfaces, it can also have straight sides arranged in perpendicular or nonperpendicular fashion. One or both of the layers are transparent or translucent. Although the drawing illustrates the layers as being relatively thick, in actual practice the layers can. be quite thin, such as 1 or 2 mils, with the cell having a maximum height WO 92/13368 PCT/US91/0060?
a~o~o~~.~:

or clcpLl~ of C~.S or 1 mil.
Gnc: crnbc~clinrent c>f the swivch 49 of the present invention is illustrated in 1'lGs. G and 7. The switch 49 has a base layer 46 and a resilient i.op layer 48, whicin is attached to the base layer.
0~ Conductive leads or layers 50a and 50b are sandwiched between the two layers. The conductive layer 50a on the left side of the device is separated from the conductive layer 50b on the right side of the device by spacing 51. A portion of the top layer is bulged out to fornr a bubble element 56. A conductive strip or coating 54 is attached to the inner side 55 of the bubble element. The bubble element is biased away from the base layer 46 as sbown in FIG. 6 so that the conductive strip or coating does not come in contact with the switch contacts 52. Thus the .switch is nox~ally in the off position.
When the bubble element is pref>sed downwardly towards the base layer as shown in FIG. ?, the conductive strip 54 contacts the switch contacts 52; thus bridging the contacts and permitting current flow across the contacts between the conductive leads or layers 50a and 50b, as illustrated FIG. ?. When pressure is removed from the bubble element, the bubble element biases away from the base layer, breaking contact between the two contacts 52.
An alternative embodiment of the switch 44A of the present invention is illustrated in FIG.. 8. This switch has a base layer 46, a resilient top layer 48, and conductive leads or layers 50 sandwiched between the two layers. The top layer is bulged out to foroo a bubble 2, element 56. The switch contacia 52 are located on the inner sides of the bubble element. A conductive strip 54 or coating is attached to the inner side of the base layer 46. This switch operates in the same :r~:uumr as sloes tine switch of Fltis. 6 and 7. The bubble element is delnre~secl t.o have the swi tch contacts 52 make contact with the ccmcluctive si.rip 59; thus, ele~~trically bridging the two contacts.
71~e hubUle element is biased away from the top layer so that the U5 switch is «orTnally in an off position. When pressure is removed form the bubble element, the bubble element biases away from the conductive strip; thus, breaking contact between the switch contacts and the conductive strip.
hnother embodiment of the battery-strength indicator device of l0 the present invention is illustrated in FIG. 9. The device lOC has a first layer 30 and a second layer 32. Conductive layers 14a and 14b are independently and separately sandwiched between the first and second layers on the left. and right sides respectively of the device.
A portion of the first layer is. formed into a bulge 3? to form the 15 indicator cell 12. A plate or electrode 60a is attached to the inner surface 31 of the top layer vrithin the cell and is electrically connected with conductive layer 14a. A second plate or electrode 60b is attached to the inner side 35 of the second layer 32 within the indicator cell and is electrically connected to the conductive layer 19b. The indicator cell is filled with an indicator material 17, such as the material described above. At least one of the layers and its attached plate are transparent or translucent (or one of the layers is transparent or translucent and its attached plate is extremely thin) so that changes to the indicator material are risible.
The basic architecture of the indicator device of FIG. 9 can also be utilized for another embodiment of the switch of the present invention. When the architecture is employed as a switch, the bulge . ~ CA 02101077 1999-10-27 37 is biased away from the second layer 32, and the indicator cell is not filled with an indicator material.
Two switch contacts replace the electrodes 60a and 60b and the switch operates when the bulge is depressed downwardly S to make contact between the switch contact attached to the inner side of the first layer and the switch contact mounted on the inner side of the second layer.
Another embodiment of the battery-strength indicator device of the present invention is shown in FIG. 10. The indicator device 100 is a strip like device having first and second superimposed non-conductive layers 30 and 32 which are attached together in the same manner as strips 30 and 32 in FIG.. 3. At least one of the strips is transparent. Conductive layers 64 are sandwiched between the first and aecond layers. The conductive layer is reduced to a small cross-section 65 in the indicator zone 66. Within the indicator zone, the conductive layer is covered with a small amount of a pyrotechnic chemical 68 sensitive to heat . Surrounding the pyrotechnic chemical is a color indicat_Lng heat-sensitive material 70 which will undergo a visible color change, either permanent or temporary, when the material is heated to at least a predetermined temperature. This battery-strength indicator device is a one-shot device; the pyrotechnic chemical will only decompose or react once. The pyrotechnic chemical undergoes rapid decomposition when it is heated to a predetermined i:emperature. The resistance of the conductive layer in the reduced cross-sectional area 65 is selected such that current flow at a minimum predetermined voltage through the conductive layer will raise the area to a predetermined temperature which will cause the pyrotechnic chemical to decompose or otherwise react. The pyrotechnic chemical in turn will raise the 210107' temperature of the color-indicating, heat sensitive material to the predetermined temperature for color change.
AltimugU the indicator device of FIG. lOD is shown with a color-indicating, teat-sensitive material, the device can also be OS fabricated with the pyrotechnic chemical alone, thereby causing a slight charring to the strip which is noticeable. One of the strips can also be made of a material that is sensitive to temperature and will w~dergo a visible change when the temperature exceeds a predetermined value. Alternatimely, the device can be fabricated without the pyrotechnic chemical, relying on the color-indicating, heat-sensitive material alone to indicate whether the battery has a predetermined minimal voltage output. If the color indicating, heal-sensitive material uudergoes~ a non-permanent color change when exposed to a predetern~ined temperature, then the battery-strength indicator device of I'IG. lOD can be used repeatedly to determine if the output voltage of the battery meets a predetern~ined voltage level.
I1 further embodiment of the battery-strength indicator device of Lhe present invention is illustrated in FIG. 11. The battery-strength indicator device l0E has first and second layers 30 2o and 32 which are sandwiched togeaher like layers 30 and 32 in E'IG. 3.
The conductive layers fi4 are sandwiched between the first and second layers. The conductive layer is reduced to a small cross-section area 75 within the indicator cell 66. The resistance of the conductive layer and the cross-sectional area 75 are selected such that the ?5 current flow of a predeteimined~ minimum voltage potential through the conductive layer will melt the area 75 in the fashion of a fuse element, causing the conductive strip in area 75 to become an open ~~101~~~

cirrui l.. The vaporization of t.tve melted conductive strip imms a vi:~it~lc~ sip, that the area 7~~ was heated to a predetennined te«;l~crature whic:W :an only be achieved when the device is subject t.o a hreciet.erniined minimwn voltage.
U5 rlnotl~er cmbodiment of the invention is shown in FlG.s 12 and 13.
A buttery package 84 comprises two batteries 18 mounted on a package frame F~2. Conductive leads 14a aJ~d 14b are affixed to the base of the frame in electrical contact with the cathode 22 of the battery. A
conductive lead 14 connects the leads 14a and ~~lb with a battery lU strength-indicator 10, such as the ones described herein. A
conductive layer 50 connects the indicator 10 with the switch 44 which in turn is connected to a conductive T-connection 86. The T-connection is electrically connected to the battery anodes 20 via conductive layer 50 and conductive flaps 86. The package is intended 1; to be covered with a transparent cover giving physical access to the switch 44 and visual access to the indicator 10. In the embodiment if 1'1G. lz tt,e batteries are in parallel. FIG. 13 illustrates the circuitry of a battery package containing two batteries that are connected in series to the swite:h 44 and indicator 10.
2U In the preferred embodiment of the conductive leads, switch and indicator are layers attached to the package frame. The conductive leads may be printed or silk screened directly on the package frame.
The package frame can be the base nonconductive layer for the switch 99 and indicator 10.
25 Another embodiment of the switch 44 of the present invention is illustrated in FIG. 14. The switch has a base layer 46 and a top layer 48, which is attached to the base layer. Conductive leads or 21 010 7 ~' .~;~
19 - _ 1<ry:r:: ;,y, ,uy SUb are sandwi~~hed between Lhe two layers. The rcnuiuc:yvc. layer. 5Ua on the left side of the device is formed into ~u~lclr contact G2a in chamber 40 and the conductive layer 50b on the right side of the device is fonned into switch contact 52b in the 05 clranrUer. A portion of the top layer and bottom layer are bulged out top fonn bubble elements 56a and ;56b. The bubble elements are biased away from each other so that the switch contacts do not come in contact. Tlms, the switch is nonnally in the off position. 15'hen the bubble elements are pressed together as shown by the arrows in FIG.
19, the switch contacts come in contact permitting current flow across the contacts and the condtsetive leads or layers 50a and 50b.
w't~en pressure is removed fran the bubble elements, the bubble elements bias away from each other, brealking contact between the two switch contacts.
1, The present invention permits the user of a battery to quickly determine whether the capacity o:f the battery is above or below a given point without the use of a voltmeter and/or aumeter. The approximate capacity of a battery can be determined by the battery's no load output voltage. The indicator device of the present invention can be fabricated so that it indicates a particular no-load voltage threshold. For example, one can select a voltage threshold which is indicative that the battery is about 20~ exhausted, or about 50~
exhausted - whatever is suitable for the intended purpose, The indicator having a liquid-crystal composition comprises a sealed, fully-enclosed cell containing the liquid-crystal composition.
Preferably, one side of the cell will be transparent, and not merely translucent. The base layer of the liquid-crystal indicator cell can ~~ ~r~.i~
WO 92/13368 PCT/US91/0060.?
~~ o~o~~ .~

t~c~ :r I~iy.l~-ciiolectric nmterial, optionally coated with a dielectric frilr~l~(~1' in o.c>ot.act. with the liquid-crystal composition. The top layer is )~i'c~l~~ral~ly transparent and, optionally, has a transparent, ccn~ductive coating applied to the surface in contact with tire 05 liduid-crystal composition. A voltage differential is induced across tic liquid-crystal composition to either the base high-dielectric material car the high-dieleetri~~ transparent top layer to induce elc~c:tric field. An electric field change can cause changes in the optical properties of liquid crystals, such as wh~ci a liquid crystal changes from a nematic phase to a smectic phase. Such field are easily achieved, even with small voltage inputs from batteries, by employing a high-dielectric base material and/or a high dielectric top layer material. Thus, when the liquid-crystal detector of the present invention is in a non-energized state, it will have one optical appearance characteristic of i:he 'at rest' phase of the liquid crystal. H't~en the indicator device is activated, and a field is generated across the liquid-cr;,rstal composition, the liquid-crystal composition will transforon into another phase. Alternatively, the indicator can remain in an "always on" condition and provide a constant indication of battery strength. If batteries do not have sufficient voltage to achieve the threshold high-dielectric field, thereby changing the liquid-crystal composition from one phase to the other, no change will be observed. Thus, each liquid-crystal indicator cell will be tailored by controlling the thickness of the dielectric material in the sandwich, the distance between the plates or electrodes, and the dielectric composition. Typical liquid-crystal compositions that can be employed include ''~O 92/13368 PCT/US91/00602 21010 7~ ~'~

rnet.io~x_,~L~en;;yliclc~rwtmt,ylaniline and terephthal-bis-p-butyl-aniline.
trr LI~e irrdic:rl.or device of 1?IG. 15, the electrodes G2b anct f>2a :vrE~ irrclcyc:rulerrLly arrd separately sandwiched between the first high dielectric constant layer and the third nonconductive layer 30 and 34 05 anct t.le first layer and secorn:3 nonconductive layers 30 and 32, respectively. l1 bulge extending outwardly from the first layer is forn~ed in Llne second layer to form an indicator cell 40. Within the cell on the inner side of the .second layer 32 and a plate G2a is attached or coated and electrically connected to le~atl 14b. Plate G2b is positioned below the indicator cell between the first and third layers and is electrically connected to conductive layer 14a. The indicator cell 12 is filled with a liquid-crystal composition 40. The second layer and plate G2a and/or the first and third layers and plate G2b are transparent or transluscent so that changes to the liquid-crystal composition 40 area visible. The bottom of the chamber can include a highly reflective coating or the like to enhance observation of the changes to composition 40. The arrangement of the first, second, and third layers of the conductive layer 14a is shown in the enlarged, sectional view of FIG. 16.
Other constructions of the battery strength indicators and switches are contemplated within the scope of this invention. For example, in indicator can be fabricated with conductive top and base layers which sandwich a nonconductive layer. A cell is formed between the top and bottom layers as ciescribed herein. The nonconductive 2, layer does not extend into the cell; this layer, however, does electrically insulate the top layer from the bottom layer. The cell is filled with an indicator material as described herein and the top . ~ CA 02101077 1999-10-27 and bottom layer are independently adopted to be connected to different poles of a battery. The top and/or bottom layer are transparent or translucent.
Another indicator embodiment contemplated by the S present invention is similar to indicator lOD of FIG. 10.
This alternative embodiment has top and base layers sandwiching a conductive layer that is reduced to a small cross-sectional area in an indicator region of the indicator. The top layer and/or base layer undergo color changes when the temperature crosses a predetermined threshold. The conductive layer in the indicator region is adopted to exceed the predetermined temperature threshold when the voltage potential across the conductive layer exceeds a predetermined voltage.
In another embodiment of the indicator, the indicator can use a BIOMETi~L* material of TOKI AMERICAN TECHNOLOGIES, INC. of Irvine, California. BIOMETAL* material is a shape memory alloy which changes its internal structure at a predetermined temperature and takes on an entirely new space. A BIOME'TAL material can be used in place of the pyrotechnic material or color indicating material of the device lOD of FIG. 10x to indicate whether the battery has a predetermined voltage.
The present: invention can be used with a dry cell battery or with a wet-cell battery and with both rechargeable and nonrechargeable batteries. However, for purposes of convenience, the invention has been described herein with respect to a dry-cell battery.
The modern nonrechargeable alkaline dry-cell battery has a declining output voltage over its useful life . A new battery has an output voltage of about 1.60 volts. After one hour of continuous use, a battery's voltage output (no load) drop to between 1.40 volts and * trade-mark ~'O 92/13368 ~ 1 0 ~ ~ ~ ~ PCT/US91/00602 z3 1.~15 volts. '1'hercaft.cr, for the majority of the battery's useful life, the Watt.ery's no-load voltage gradually decreases in a somewhat linear Iashic~«. As a battery approaches the end of its useful life, the no-load voltal;e drops to about 1.0 volt. However, the battery still has souse capacity and can be marginally used in this weakened conditioned for very brief periods of time. When the battery's voltage drops below 1.0 volt, the battery is near the end of its lice, and the remaining capacity of the battery is very limited. Near the point of exhaustion, the battery's output voltage rapidly drops from about 1.0 volt to about .5 or .G volt.
The light-output candle-power of a portable lantern or flashlight bulb is somewhat sensitive to the battery voltage.
Incandescent lamps are designed t.o operate optimally at a specific voltage. If the voltage is appreciably exceeded (such as by 50~) for any period of time, the film of the lamp will rapidly melt or vaporize, destroying the lamp. Most lamps are designed for voltages in increments of 1.2 volts. Thus" portable-lantern incandescent lamps are designed optimally for an output voltage of about 4.8 volts (a G-volt lantern), and single-cell, double-cell, triple-cell, four-cell, and five-cell flashlight incandes<xnt lamp are designed for an output voltage of 1.2, 2.9, 3.6, 4.8, au~d 6.0 volts respectively. However, flashlight and lantern bulbs will operate effectively over a broad range. For example, a two-cell lantern bulb or lamp will operate effectively from about 3.2 volts to about 2.0 volts. However, when the voltage of each battery drops below 1.0 volt, the output of the incandescent lamp is noticeably affected, and the color of the emitted light shifts from a yellow-white light to a yellow-red light.

~

Three sets of batteries were tested in three identical flashlights, with the batteries being switched between the flashlights on a routine basis. The results of the tests are shown in the' following tables. (The Roman numerals I, II, and III indicate the flashlight, and the numbers 1A, 1B, 2A, 2B, 3A, and 3B indicate the individual batteries.) The first set of batteries (lA and 1B) were ENERGIZER*
alkaline batteries; the second set (2A and 2B) were DURACELL* alkaline batteries, and the third set (3A and 3B) were EVEREADY*- zinc-carbon batteries. The batteries were "D" size batteries. Battery 2A failed after 32 hours and was replaced with a 3-year old DURACELL alkaline battery having a no-load'. voltage of 0.99 volt.
The flashlights were two-cell flashlights having incandescent lamps. The incandescent lamps were rated at 1.2 volts and 0.5 amp. The cold-filament internal resistance of the incandescent lamps was about 0.4 amp.
The hot-filament. internal resistance of the incandescent lamps was not measured.
Each flashlight was loaded with a set of batteries and turned on. From time to time, the flashlights were turned off and the no-:Load output voltage of the batteries was measured. On a periodic basis, the output voltage of the batteries under :Load was also measured. The tests were not run on a continuous, 24-hour basis, but were run for periods of approximately 12 hours during the first two days, about 3 hours the third day, about 7 hours the fourth day, about 6 hours the ninth day, and 20 minutes the tenth day. No tests were conducted during the fifth, sixth, seventh and eighth days. The results show that the useful like of a battery is near exhaustion when the voltage * trade-marks 2101077 ~~
c:J
of itm bat.t.cry l,m fallen below 1.0 volt. After the voltage of t.i~e lr.~!.t.orl~ circ>l~s hclow 1.0, the di::c:harge rate of the battery (indicated Iry t.i~c vull.a~c~ c)rc>p) can c:xcerd IJ.;, volt in a half-hour.
It appears, from the tables, that the useful life of the lA and 11,3 ~:lLteI'lE'g 15 all~uL 2~ LU 2B hours and the half-life is about 19 hours where the output voltage :is about 1.2 volts. When the output voltage of tlue batteries is about 1.3 volts, the batteries have about 75% of their operating life remaining. When the voltage of the batteries is about 1.1 volts, tine batteries have about 25~ of their useful lice remaining.
The 2A and 2B batteries appear to have a useful life of about 23 hours and a half-life of about 12 hours where the output voltage is about I.2. When the output voltage of the batteries is about 1.3 volts, the batteries have about ?5% of their useful life remaining.
When the output voltage drops to about 1.15 volts, the batteries have only about 25a of their remaining useful life.
Batteries 3A and 3B, which are zinc-carbon batteries (LeChanche cell), had a much shorter lice span than the alkaline batteries.
These batteries had a useful life of about ?.5 hours, with a half-life of about 3.5 to about 4 hours Wrhere the output voltage is about 1.2 volts. When the batteries' output voltage is about 1.3 volts, the batteries have about ?5% of their remaining useful life. When the batteries' output voltage drops to about 1.1 volts, the batteries only have about 25% of their useful Uife remaining..
2, When the no-load output voltage of the batteries dropped below 1.0 volt, all the batteries exhibited rapid voltage drops. When the batteries reacted the end of their useful life, the flashlights were . ~ CA 02101077 1999-10-27 turned off and. the batteries were allowed to rest.
Surprisingly, the batteries' output voltage would rebound and the batteries could be operated for brief periods. As this cycle of rest and use was continued, the batteries' ability to rebound decreased and the batteries experienced much more rapid voltage drops under the load.
The tests indicate that, when the batteries are fresh, the total voltage drop of a pair of batteries in series is somewhere from about 0.45 to about 0.65 volt; that is, the total output voltage of the two batteries in the flashlight under no-load will be about 3 volts, and under the load will be about 2 . 5 volts . As the batteries approached their half-life, the voltage drops for the two batteries increased to about 0.75-about 0.95 volt. When the batteries approached the end of their useful life, the voltage drop was in excess of 1.0 volt; that is, the output voltage of the two batteries under no-load was from about 2.0 to about 2.2, and the voltage drop was from about 1.0 volt to about 1.7 volts.
The test also show that, when batteries have reached their exhaustion point but are allowed to rest for a few hours, their no-load output voltage will exceed 1.0 volt.
However, when the batteries are then put under a load, the working voltage of the batteries rapidly drops to as low as 0.6 volt. This voltage drop can be observed because the output voltage of the batteries in the weakened condition does not drop in a single-step manner but continues to drop over time, sometimes taking as long as 30 seconds to stabilize. For example, two used DURACELL alkaline batteries, each having a no load output voltage of about 0.95 volt, were F>laced (i.e. , used) in a flashlight for one hour. At the end of one hour, the no-load output voltage of the batteries was about 0.45 and 0.5 volt, respectively. The batteries were put under a load, and the voltage immediately dropped between 0.6 and 0.7 volt, for both batteries in series, and then continued to drop, over a 30 second period, for a final value, for both batteries in a series, of 0.48 volt. This same type of phenomenon was observed with the ENERGIZER alkaline batteries and with the EVEREADY zine-carbon batteries. Thus, the device equipped with exhausted batteries may give a strong operation for a :short period of time, but then will quickly decrease in power under the on-going load.

BATTERY OUTPUT VOLTAGE IN OPERATION
(Incandescent Flashlight Bulb) Time (Hours) Battery Voltacre lA 1B 2A 2B 3A 3B

0.00 1.60 1.60 1.59 1.60 1.60 1.60 1.00 1.45 1.45 1.45 1.45 1.35 1.35 1.50 1.40 1.45 1.40 1.40 1.30 1.30 2.00 1.40 1.40 1.35 1.35 1.30 1.30 2.50 1.39 1.39 1.35 1.35 1.30 1.30 3.50 1.39 1.39 1.32 1.32 1.20 1.20 4.50 1.39 1.39 1.30 1.30 1.20 1.19 5.50 1.30 1.30 1.30 1.30 1.10 1.10 6.50 1.30 1.30 1.30 1.30 1.05 1.02 7.50 1.30 1.30 1.29 1.29 1.01 1.01 10.00 1.29 1.29 1.28 1.25 0.89 0.75 11.00 1.28 1.28 1.25 1.25 0.80* 0.55*

12.00 1.25 1.25 1.20 1.20 0.75* 0.60*

12.50 1.20 1.20 1.20 1.20 0.78* 0.60*

TEST DISCONTINUED FOR .25 HOURS

12.50 1.35 1.35 1.36 1.36 1.25 1.20 12.75 1.30 1.30 1.30 1.30 1.05 0.90 13.00 1.29 1.29 1.28 1.26 0.95 0.75 13.25 1.27 1.25 1.25 - 0.80 0.51 13.50 1.26 1.25 1.25 1.25 0.89 0.70 8 PCT/US91/00602.
a~io~o~~~~~
W
1~')(~ 1.~~ 122 1. Z1 1.20 0.71 O.JS

1:.25 1.21 1.21 1.2U 1.20 U.91 0.8U

1C.'~5 1.21 1.20 1.18 1.18 0.61 0.40 1?.?-~~ 1. z0 1.20 1.18 1.16 0.6U O.OU

18.:0 1.20 1.19 1.15 1.15 DISCONTINUED

19:~U 1.19 1.16 1.10 1.10 DISCONTIMIEU

20.SU 1.13 1.11 1.10 1.10 0.99 0 22.25 l.lU 1.10 1.09 1.05 0.99. .
0.00 23.2:> I.US 1.05 1.01 1.01 0.55 0.00 24 . 50 1. (15 1. U5 0 . 0 . 93 0 . 80 0 . (1U
fi9 25.75 1.02 1.02 0.49 0.90 D1SCONTINUL'U

TE.~'i' DIS00NTINUL'U 9 ilOUf,S
FOR

25.75 1.19 1.20 1.20 1.20 -- --2G.75 1.01 1.01 0.99 0.99 -- --27.90 1.00 1.00 0.95 0.95 - --28.50 0.99 0.99 0.85 0.8G - --'f hST U 1 SUONT I 21. 5 i NUED FOR LOURS

28.50 1.11 1.12 1.12 1.11 -- --29.SU 0.99 0.99 0.90 0.89 -- --32.25 0.94 0.95 0.39 0.95 - --32.25 0.98 0.98 0.99* 0.90 - --34.40 0.81 0.91 0.91* 0.80 - --35.75 .65 .65 .65* .65 - -TEST DISOONTINUED FOR 112.5 HOURS

35.75 1.09 1.09 1.12* 1.10 - --40.35 .65 .65 .65* .65 - -_ TEST DISOONTINUL'D 3.25 iiOUR~~
FOR

40.35 0.98 0.99 0.95* 0.98 - -41.35 0.60 0.52 0.45* 0.54 - --TEST DISOONTINUED FOR 13.75 HOURS

41.35 1.01 1.01 0.99* 0.9? - --91.70 0.71 0.79 0.50* 0.70 - --41.70 0.90 0.91 0.80* 0.81 - --*lteplacement for i3attery 2A
Table II sets forth the: measured battery voltage drop of batteries lA, 1L3, 2A, and 2B under load. The test were coamenced when the batteries passed their operational half-life. As can be seen, the voltage drop of a battery under load increased as the battery OS approached the end of its useful life. More indicative than the actual drop, is the amount of time it takes to stabilize the voltage under load. During the useful life of the battery, a voltage drop from the no-load voltage to the load voltage of the battery is an z9 imnecliat.c sirylc~-stelr vult.age chap. Wren the batteries are t~cyond t.lwir useful life, the voltage drop is a continuous, slow drop that can Lake some tune to stabilize, sometimes exceeding 30 seconds. This is indicative that the batteries are exhausting their limited U5 calaci lies.
TABLE II
BATTERY VOLTAGE DROP UNDER LOAD
(Incandesc:ent Flashlight Bulbs) Batteries Batteries lA & 113 2~~ & 2B
Test No Voltage No Voltage Time Load Under VoltageLoad Under Voltage (llrs)Voltage Load Drop Voltage Load Drop 16.252.39 1.96 0.43 2.30 1.88 0.47 18.502.35 1.89 0.46 2.28 1.89 0.30 20.502.30 1.85 0.45 2.20 1.80 0.40 22.252.23 1.80 0.43 2.10 1.71 0.39 23.252.15 1.61 0.54 2.05 1.51 0.54 24.502.11 1.60 0.51 1.90 1.49 0.41 25 - ~= - 1. 94 1. 46 0 .
. 4 8 D HC)<IR,S
I
SCANT
I
HUED

25.752.32 1.70 0.62 2.35 1.75 0.60 26.752.08 1.40 0.68 2.01 1.52 0.49 27.902.02 1.40 0.62 1.82 1.30 0.52 PEST FOR21.5 DISCONTINUED HOURS

29.501.99 1.29 0.70 1.81 1.20 0.61 32.251.92 1.35 0.57 1.49* 0.10* 1.39*

TEST DISOONTINUEDFOR 112.5NIOURS

35.752.18 1.31 0.87 2.21* 1.10* 1.11*

TEST D I SC'ONTFOR 3 HCK1RS
I NUED . 25 91.351.80 0.91 0.89 1.00* 0.48* 0.52*

*Replacement for Battery 2A

Claims (26)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A non-rechargeable alkaline battery having a battery strength indicating means to indicate the strength of the battery comprising:
a non-rechargeable alkaline battery having a first terminal and a second term i nal;
a battery indicator and switch means comprising a non-conductive base layer, a non-conductive top layer disposed over the base layer, a first chamber formed between the top layer and the base layer, and a second chamber spaced from the first chamber and formed between the top layer and the base layer;
indicating means disposed in the first chamber;
first conductive means electrically connected to one terminal of the battery and to one end of the indicating means;
second conductive means connectec9 to the opposite end of the indicating means and extending into the second chamber;
third conductive means extending from within the second chamber and extending to contact the other terminal of the battery; and whereby the second conductive means and the third conductive means in the second chamber are spaced apart and said second chamber being deformable so that upon pressing of the second chamber the second conductive means will electrically contact the third conductive means thereby placing the indicating means in electrical contact across the terminals of the battery to indicate the strength of the battery.

2. The battery of claim 1 wherein the indicating means in said first chamber undergoes a visible change when subject to at least a predetermined voltage value.

3. The battery of claim 1 wherein at least the top layer of the first chamber is transparent.

4. The battery of claim 1 wherein at least the top layer of the first chamber is translucent.

5. The battery of claim 1 wherein the indicating means is a chemical redox composition which changes color when the voltage potential across the terminals of the battery crosses a predetermined voltage.

6. The battery of claim 1 wherein the indicating means is a liquid crystal composition that changes phases when the electrical field across the chamber exceeds a predetermined value.

7. The battery of claim 1 wherein the second chamber upon being depressed will remain depressed thereby completing the circuit and placing the indicating means across the terminals of the cell.

8. The battery of claim 1 wherein the first conductive means comprises a conductive layer which has a reduced cross-sectional area in said first chamber and the indicating means in said first chamber comprises a heat sensitive color indicating material adapted to undergo a color change when the temperature in said first chamber rises to a predetermined temperature when the voltage of the current following through the conductive layer exceeds a predetermined value.

9. The battery of claim 1 wherein the first conductive means comprises a conductive layer which has reduced cross-sectional area in said first chamber and wherein the indicating means comprises pyrotechnic material adapted to decompose when the temperature of the conductive layer in said first chamber exceeds a predetermined temperature, the conductive layer in said first chamber is adapted to exceed said predetermined temperature when the voltage of the current through said conductive layer exceeds a predetermined value.

10. The battery of claim 1 wherein the first conductive means comprises a conductive layer which has reduced cross-sectional area in said first chamber such that when the voltage of the current following through the conductive layer in said first chamber exceeds a predetermined value the current flowing through said conductive layer in said first chamber raises the temperature of the conductive layer in the chamber to the melting point of the conductive layer causing the conductive layer to melt at the reduced cross-sectional area.

11. The battery of claim 1 wherein the indicating means is a light emitting diode that undergoes a visible change when the voltage applied to the light emitting diode crosses a predetermined value.

12. A non-rechargeable alkaline battery having a battery strength indicator comprising:
a non-rechargeable alkaline battery having a first terminal and a second terminal;
a battery indicator formed in a layer attached to a side of said battery which undergoes a visible change when subject to a voltage potential which exceeds or drops below a predetermined value and a first conductive lead electrically connected between one end of said indicator and said first battery terminal; and a battery switch comprising a resilient, nonconductive layer disposed over the side of said battery, a switch chamber formed beneath said resilient layer, a second conductive lead extending from within said chamber and connected to the opposite end of the indicator, said portion of said second conductive lead within said switch chamber comprising a switch contact, and a conductive layer normally spaced apart from said switch contact and in electrical contact with said second battery terminal, said battery switch being biased in an electrically open position, whereby upon pressing of the resilient layer over said switch chamber, the switch contact will be placed in electrical contact with the other terminal of the battery, thereby placing the indicator in electrical contact across the terminals of the battery to indicate the strength of the battery.

13. The battery of claim 12 wherein said resilient layer is transparent about the chamber.

14. The battery of claim 12 wherein said resilient layer is translucent about the chamber.

15. The battery of claim 12 wherein said indicator comprises a chemical redox composition which changes color when the voltage potential across the indicator crosses a predetermined voltage.

16. The battery of claim 12 wherein said indicator comprises a liquid-crystal composition which changes phases when the electric field across the indicator exceeds a predetermined value.

17. The battery of claim 12 wherein said indicator comprises a LED which undergoes a visible change when the voltage applied to the indicator crosses a predetermined value.

18. A battery package having a battery-strength indicator comprising:
a package frame;
at least one battery mounted on said package frame, said battery having first and second terminals;
a battery-strength indicator mounted on said package frame and electrically connected to said first terminal of said battery; and a battery switch comprising a resilient, nonconductive layer disposed over said package frame, a switch chamber formed beneath said resilient layer, a pair of switch contacts normally spaced apart in said chamber, one of said switch contacts being electrically connected to said battery-strength indicator and the other of said switch contacts being electrically connected to said second terminal of said battery, said battery switch being biased in an electrically open position, whereby upon pressing of the resilient layer over said switch chamber, the switch contacts will place said indicator in electrical contact across the terminals of said battery.

19. A non-rechargeable alkaline battery having a battery strength indicator comprising:
a non-rechargeable alkaline battery having a first terminal and a second terminal;
a battery-strength indicator comprising a first nonconductive layer disposed over the side of said battery; a second nonconductive layer attached to the first nonconductive layer, a portion of said first: and second nonconductive layers forming in part an indicator chamber therebetween; a conductive layer sandwiched between said first and second nonconductive layers, the conductive layer reduced to a small cross-sectional area in the chamber; a heat-sensitive color-indicating material in said chamber that is adapted to undergo a color change when its temperature crosses a predetermined value, the conductive layer in the chamber rising to the predetermined temperature when the voltage of the current flowing therethrough exceeds a predetermined value; and a first conductive lead electrically connected between one end of said conductive layer and said first battery terminal, and a battery switch comprising a resilient, nonconductive layer disposed over the side of said battery, a switch chamber formed beneath said resilient layer, a second conductive lead extending from within said chamber and connected to the opposite end of the indicator, said portion of said second conductive lead within said switch chamber comprising a switch contact, and a conductive layer normally spaced apart from said switch contact and in electrical contact with said second battery terminal, said battery switch being biased in an electrically open position, whereby upon pressing of the resilient layer over said switch chamber, the switch contact will be placed in electrical contact with the other terminal of the battery, thereby placing the indicator in electrical contact across the terminals of the battery to indicate the strength of the battery.

20. The battery of claim 19 wherein said first layer of said battery strength indicator is transparent about the chamber.

21. The battery of claim 19 wherein said first layer of said battery strength indicator is translucent about the chamber.

22. A non-rechargeable alkaline battery having a battery strength indicator comprising:
a non-rechargeable alkaline battery having a pair of terminals; and a battery strength indicator disposed over the side of said battery having (i) a conductive layer, (ii) a temperature sensitive color indicator material in thermal contact with the conductive layer wherein the conductive layer has sufficient heat generating capacity to effect a change in the temperature sensitive color indicator layer, (iii) means to prevent conduction between the conductive layer and the battery to permit the heat generated by the conductive layer to change the color of the temperature sensitive color indicator material and indicate battery strength when the strength indicator is in contact with the battery, and (iv) electrical switch means positioned, when activated, to electrically connect the conductive layer and the terminals of said battery to effect a color change in the temperature sensitive color indicating material and indicate the strength of said battery.

23. The battery of claim 22 wherein said means to prevent conduction comprises a nonconductive layer.

24. The battery of claim 22 wherein said electrical switch means comprises a resilient, nonconductive layer disposed over the side of said battery, a switch chamber formed beneath said resilient layer, a switch contact within said chamber connected to said conductive layer, and a second conductive layer normally spaced apart from said switch contact and in electrical contact with one of said battery terminals, said switch means being biased in an electrically open position, whereby upon pressing of the resilient layer over said switch chamber, the conductive layer of the indicator will be electrically connected across the terminals of the battery to indicate the strength of the battery.

25. The battery of claim 22 further comprising a transparent nonconductive layer over the temperature sensitive color indicator material.

26. The battery of claim 22 further comprising a translucent nonconductive layer over the temperature sensitive color indicator material.