BELL SYSTEM PRACTICES

Plant Series

SECTION 157-601-703

Issue 1, February 1971

AT&TCo Standard

LEAD-ACID BATTERY

TROUBLE CONDITIONS

(WITH COLOR PHOTOS)

CONTENTS PAGE

1. GENERAL . . . . . . . . . . .

2. TROUBLE CONDITIONS . . . . . .

PLASTIC JARS . . . . . . . . .

2.01 Causes of Mechanical Failure . .

2.02 Positive Plate Growth and Bowing

. . . . . . . . . . . . . . .

2.04 Strap Growth . . . . . . . .

2.05 Crazes and Cracks . . . . . .

2.06 Cracks and Leakage . . . . .

2.07 Leaking Jar-Cover Seals . . . .

2.08 Negative Plate Troubles . . . .

2.09 Needle Growth . . . . . . .

2.10 Sulfation . . . . . . . . .

HARD-RUBBER JARS . . . . . . .

2.11 Cover Rise . . . . . . . . .

2.12 Allowable Plate Growth . . . .

ILLUSTRATIONS

Fig. 1—C & D Cutaway View . . .

Fig. 2—Exide Cutaway View . . .

Fig. -Gould Cutaway View . , .

Fig. 4—Positive Plate Growth, Plate

Touching Jar, Nosing Effect (Gould

Cells) . . . . . . . . . . .

1

5

5

s

5

~

6

6

b

6

6

6

7

7

7

2

3

4

8

CONTENTS PAGE

Fig. 5—Plate Bowing (C & D Cells)

. . . . . . . . . . . . . 9

Fig. 6—Strap Growth—End of Strap

Nosing on Jar (Exide Cells) . . . 9

Fig. 7—Crazing in Strap Area (C &

D Cells) . . . . . . . . . .9-

Fig. 8-Cover Cracks (Gould Cells) . 10

Fig. 9—Jar Crack in Strap Area-Typical

With Exide Cells . . . . . . . 10

Fig. 10—Leaking Jar Crack in Strap

Area—Typical with C & D Cells . . 10

Fig. 1l—Jar-cover Seal Seam Leakage

(Gould L152C-1965) . . . . , . 11

Fig. 12—Negative Plate With Heavy

Cracks (Exide Cells) . . . . . . 11

Fig. 13—Needle Growth—Needles

Grown More Than 1/4 Inch (C & D

Ceils) . . . . . . . . . . .12

1. GENERAL

1.01 This section describes the trouble conditionsof lead-calcium and lead-antimony cells and

batteries.

1.02 This issue affects Equipment Test List.

1.03 Evaluation of the design of lead-acid batteriesin plastic jars indicates they have been

prone to mechanical failure in about 10 to 15 yearsas a result of stresses produced by growth ofinternal members causing jar breakage and resultant

American Telephone and Telegraph Company, 1971

Printed in LI.S.A. Page 1

SECTION 157-601-703

/

NEGATIVE STRAP

PLASTIC

‘AR\ pPOSITIVE PLATE

POSITISTR

/

VEAP

\ Y5?&ll

/SUPPORT BAR

C&D

{

SEPARATORS

//

/

/“”\

~% ~POSITWE PLATE

\BETWEEN SEPARATPLASTIC

JAR RIDGEFOR NEGATIVE

PLATE SUPPORT\ NEGATIVE PLATE

‘ORS

Fig. l-C&D Cutaway View

Page 2

I

1SS 1, SECTION 157-601-703

SEPARATO

POSITIVESTRAP

\

NEGATIVE \STRAP~

\

IRS

POSITIVE PLATBETWEE

SEPARATOR

>

0

NEGATIVE PLATE~/

///

LNEGATIVE PLATE FOOT

Fig. 2—Exide Cutaway View

,

I

//

\

i

/’-POSITIVE STRAPHUNG ON JARWALL LEDGE

I EXIDE

/

POSITIVEPLATE FOOT

,STICPLAT

JAR RIDGE“E POSITIONING

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SECTION 157-601-703

POSITIVEPLATE

PLASTICHANGER _

f

POSITIVE PLATESUPPORT HOOK

WALL LEDGE - m V

/[

NEGATIVEPLATE STRAP

// r POSITIVEPLATE STRAP

ISITIVEI

PLATESUPPORT

~, HOOK

1!

1!

~ GOULD

,oRJ$&$:ifi\ -PLATE SUPPORT

PLASTIC JARll$j&OSITIVEBOTTOM PLATE

/

LSEpARATOR

NEGATIVE PLATE

Fig. 3-Gould Cutaway View

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1SS 1, SECTION 157-601-703

electrolyte loss. Failures occur even sooner in cellswhere clearances between the internal membersand the jar are minimal, or where poor castingquality causes accelerated growth of internalmembers such as straps, plates, and posts+.

1.04 Hard-rubber jars generally constrain lateralgrowth of the plates, but the covers can be

pushed up due to the method of construction.Where the plates are bottom-supported, cover riseshould be anticipated. However, cover rise canalso occur with top-supported plates.

1.05 Plate and strap growth is due to oxidationof the lead, causing lead to change to lead

dioxide. Lead dioxide occupies more volume thanlead, consequently the positive plates and strapsexpand. This growth occurs in both lead-calciumand lead-antimony cells.

1.06 Field forces should be on the alert to detectcrazed and cracked cell containers and should

arrange to order cell replacements before leaksoccur. Acid leakage can cause short circuitsand corrosion and create apotential tire hazard.

1.07 For supplementary information on lead-acidbatteries, refer to those Sections listed in

the NUMERICAL INDEX—DIVISION 157 of Section157-000-000, with special attention to Sections157-601-101, -301, -7,9, and -~, and Section157-621-101.

2. TROUBLE CONDITIONS

PLASTIC JARS

2.01 Causes of Mmhanicai Ftiure: The moreprevalent causes of mechanical failure which

may be expected in batteries with plastic jars arelisted as follows:

(a)

(b)

(c)

jar.

(d)

C’&D: (Prior to 1962) growth of positivestrap and positive plate support bar. Fig. 1.

Exide: (Prior to April 1965) growth ofpositive strap. Fig. 2.

Gould: Grid growth causing positive platesupport hooks (fingers) to exert pressure onFig. 3.

CIunmon to AU: Growth of positive postsand plates (all age periods).

2.o2 Positive Plate Growth and Bowing: Plategrowth can be gauged by eye. Only the

positive plates are expected to grow. When new,the positive plate edges do not project beyond theseparators. As growth progresses, the plate edgeswill gradually grow out past the separators andeventually touch the inner wall of the jar. Furtherplate growth will apply pressure to the jar wallwhich may be indicated by nosing of the plateedges or flattening of the black plastic wrapper(where so equipped) against the jar wall. Plategrowth will also occur in the vertical plane. andin some designs, apply pressure on the cover inan upward direction or grow vertically downwardand touch the plastic jar ridge used for positioningor supporting the negative plate. An estimate ofplate growth can be obtained by comparing theposition of the lower edge of the positive plateswith the bottom of the adjacent negative plateswhich do not grow.

2.03 In Fig. 4, the positive plates have grownlaterally beyond the separators with maximum

growth visible at the point just above the verticalarrows. Nosing is just beginning in the areaindicated by the two horizontal arrows (2). Plategrowth in the thickness dimension (or bowing orcupping of the plates as shown in Fig. 5) cancause the outside negative plates to exert pressureon the end walls of the plastic jar and may causecrazing and, ultimately, cracking to occur at thepoint of contact between the jar wall and the plasticjar ridge which supports or positions the negativeplate. The KS-5553 and KS-15544 List 300 and 400cells of all manufacturers are subject to thisdifficulty. The KS-5553 and KS-15544 List 500series C&D cells and Gould cells prior to 1963would be expected to show this defect. The KS-5361List 140 through 151 Gould and C&D cells mayalso show this defect. In Fig. 5, a vertical redreference line has been superimposed between thearrows to more clearly indicate the degree ofbowing.

2.04 Strap Growth: The upper edges of thepositive plate are burned into a lead bar

which is called a strap. These straps can growenough to apply pressure to the jar wall as illustratedin Fig. 6. In some designs the Exide and C&Dstraps are adjacent to the plastic jar wall. TheGould strap is located inward from the wall andhas individual plate hangers hung into a plastichanger which rests on the inner wall edge of thejar. Where either the strap or the plastic hangeris nosing on the jarare usually evident.

wall, flattened air bubbles

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SECTION 157-601-703

2.05 Crazes and Cracks: Fig. 6 and 7 illustratecrazing. Fig. 8, 9, and 10 illustrate crack

patterns typical of each supplier’s product. Jarcracks are usually preceded by crazing of the jarat the plate or strap pressure point. Compare Fig.6 with 9 and Fig. 7 with 10, Crazing is hard tosee but shows up under a light beam as a groupof hairline cracks. For safety, use a flashlighthoused in a nonconducting material (plastic orrubber).

2.06 Cracks and Leakage: Cracks due to plateor strap growth may occur in the jar cover

(see Fig. 8) and extend over to the jar. Replacecracked or leaking containers. See Section 157-601-201for allowable limits on scratches at installation.Where the cracks are above the electrolyte level,leakage may not occur but the explosion-proof ventis bypassed. Effort should be made to detectcracks and to order replacement cells before leaksoccur. Where cracks are below the electrolytelevel, but not leaking, it is only a matter of timebefore continued strap or plate growth will causeleakage. (See Section 157-601-701 for procedureto temporarily seal plastic jar cracks.)

2.07 Leaking J2u-cover Sea.Is: Because of poordesign or workmanship, or as a result of

stresses caused by vertical plate growth, jar-coverseals may in time crack, separate, and leakelectrolyte (see Fig. 11). Where cracks and leaksoccur, the effectiveness of the explosion-proof featureis bypassed, the potential fire hazard is increased,and cell repair or replacement is indicated. SeeSection 157-601-701 for possible repair of seals onhard-rubber cells. In small power cell designs (L140through 151), the use of flexible connectors permitsaccidental contact of adjacent cells in crowdedinstallations. Where such cells have leaking orcracked jar-cover seals, experience has indicatedthat an intercell short can develop from the leakingelectrolyte which may cause either a fire or explosionor both. In general, the seals used in Gould cellsof the L140 through L151 design appear mostprone to this defect, but cells of other manufactureshould be carefully checked. $A faulty jar-coverseal with electrolyte leakage can be detected withthe use of a voltmeter (Weston Model 931, range300/150/75/30). One lead of the voltmeter isconnected to ground and the other lead is used toprobe the seal area. If the reading obtained isgreater than 50 percent of the battery voltagemeasured between ground and the higher voltageterminal on the tested cell, a serious leak is

indicated. In the case of tank cells where aconvenient ground point may not be available, oneof the cell terminals can be used in place of aground point. In such a case, a reading of morethan 1 volt indicates a leak. If a leak is detected,the top of the jar cover and cover seal should bethoroughly cleaned and neutralized, rinsed anddried, and the voltage rechecked to locate thesource of the leak. Check for leaks annually ormore often if required.~

2.08 Negative Plate Troubles: The outsidenegative plates in C&D cells and Exide cells

have one surface visible. The outer surface ofGould negative plates has a much closer gridstructure that is not expected to show defects.On the outer surfaces of C&D or Exide negativeplates, minor cracks or voids (up to three missingpaste pellets) are permissible when new. Withaging, however, the active materials can shrink orcrack heavily, thus separating the active materialfrom the lead grid structure and degrading electricalcontact with the lead grid structure. A 5-hourdischarge capacity test (see Section 157-601-701)will determine whether or not the cell should bereplaced. Fig. 12 shows an Exide battery withheavy cracks in the negative plate.

2.09 Nde growth or other crystalline-lookinggrowths, have been observed on the negative

plates of some cells (see Fig. 13). All C&D cellswith plastic separators manufactured from 1954 to1965 are expected to show this defect. Cells ofother manufacturers may also be affected. Noserious effect on battery performance is expectedunless these growths lengthen to the point ofcontacting the positive plates and this has neverbeen known to happen. Although needle growthdoes not normally cause trouble, cells showingneedles should be carefully checked to insure thatvoltage and specific gravity remain within limits(per Section 157-601-701) and show no decliningtrend. In case of any doubt, run a dischargecapacity test.

2.10 Suz!llation:

(a) Indications of SulKation:

(1) Sulfation may occur after a long periodon an open circuit, after long operation

at abnormally low float voltage, or whencontaminating material is contained in theelectrolyte (see Section 157-601-101). A decline

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1SS 1, SECTION 157-601-703

in the voltage of one or more cells indicatespossible sulfation. This is not to be confusedwith low voltage of a few cells immediatelyafter a charge where the voltage will returnto normal after a month or two at properfloat voltage.

(2) In lead-antimony cells, sulfate usuallyappears first in the outside surface of

the outside negative plate in the bus bar lugcorner of the plate. The affected area is

Page 6.1

Added November 1971

1SS l, SECTION 157-601-703

lighter in color than the rest of the plate,and the line of separation between the twoareas frequently runs diagonally across thelugcorner of the plate.

(3) A cell with little gassing, when the othercells in the same string are gassing heavily,

should be suspected ofsulfation.

(b) CorrectingSulfation:

(1) Sulfation can sometimes be overcome bya special charge, consisting of a boost

charge (see Section 157-601-701), followed bysufficient charging to put in 2 or 3 times the8-hour rated capacity of the battery inampere-hours.

(2) If there is reason to believe that sulfationis caused by contaminating materials, such

as iron in the electrolyte, an electrolyte sampleshould be sent to the battery manufacturerfor analysis and recommendations.

(3) For further information on sulfation, referto Section 157-601-101. If sulfation is

suspected, it should be reported throughsupervisory channels.

HARD-RUBBER JARS

2.11 Cover Rise: Cover rise occurs on allhard-rubber jar batteries. The cover rise

is due to plate growth in the vertical directionand may be accentuated by the method of construction.With Exide batteries of early design, the platesare bottom -supported and cover rise is a directmeasurement of plate growth. Excessive coverrise results in breakage of the jar cover seal. Thisusually occurs when cover rise is greater than 3/4inch. When it reaches this amount, the positiveplates are very likely to short against the negativestrap. See Section 157-601-701 for procedures onresealing cover to jar seals of hard-rubber cells.

2.12 Allowable Plate Growth: If plate growthis excessive in the lateral direction, the

batteries will bulge and may eventually crack andburst. Bulging should not exceed 3/4 inch on largercells such as KS-5562 and should be correspondinglyless on smaller cells. To measure jar bulge, placea straight edge along the jar wall and measurethe maximum amount of protrusion from a planeformed by the jar wall corner edges.

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SECTION 157-601-703

Fig. APositive Plate Growth, Plate Touching Jar, Nosing Effect (Gould Cells)

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1SS 1, SECTION 157-601-703

Fig. 6-Strap Growth—End of Strap Nosing on Jar

(Exide Cells)

Fig. LPlate Bowing (C&D Cells)

Fig. 7-Crazing in Strap Area—(C&D Cells)

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SECTION 157-601-703

-.. -’

—---- —.—

Fig. 9—Jar Crack in Strap Area—Typical With Exide Cells

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1SS l, SECTION 157-601-703

Fig. lo-leaking Jar Crack in Strap Area—Typical With C810 Cells

Page 11

Fig. 12-Negative Plate With Heavy Cracks (Exide Cells)

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1SS 1, SECTION 157-601-703

Fig. lANeedle Growth—Needles Grown More Than 1/4 Inch (C&D Cells)

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13 Pages